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add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
#LyX 2.0 created this file. For more info see http://www.lyx.org/
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\pdf_title "Libretro - Implementing the core"
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\begin_layout Title
Libretro - Implementing the core
\end_layout
\begin_layout Author
Hans-Kristian Arntzen, Daniel De Matteis
\end_layout
\begin_layout Standard
\begin_inset CommandInset toc
LatexCommand tableofcontents
\end_inset
\end_layout
\begin_layout Abstract
This document explains how to successfully implement a library based on
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro API.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
Several reasons for why more emulators and game engines should run in
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro are outlined.
\end_layout
\begin_layout Section
Background
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch is a project that aims to be a center for “retro” gaming experiences.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
For your quick fix of 2D gaming goodness,
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch aims to provide a simple, featureful uniform interface for many
different gaming systems.
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
Libretro is an API that abstracts the inner functionality of a gaming system.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch can load a library that implements this API, give it a ROM, and
play.
A key design is that libretro implementations are loaded as libraries.
This ensures great modularity, and flexibility for a developer of a core.
\end_layout
\begin_layout Standard
Due to its simple and open API, other frontends can just as easily utilize
libretro implementations.
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
While “retro” would often imply an emulator of a classic system,
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro can also abstract a game engine.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
Classics such as
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Cave Story
\end_layout
\end_inset
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
Cave Story (NXEngine) and
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Doom
\end_layout
\end_inset
DOOM (PrBoom) have already been ported over.
\end_layout
\begin_layout Section
Portability
\end_layout
\begin_layout Standard
Most emulator authors write both the backend and frontend to their project.
The question of portability inevitably rises when the frontend is developed.
Should one target a single platform with high level of integration or take
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
a multi-platform approach with libraries like
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Qt
\end_layout
\end_inset
Qt? Backends for essentials like video, audio and input take a lot of time
and effort to get right, especially on multiple platforms.
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
By implementing for
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro, one can target standard C/C++ (or any language that can export
a C API), and achieve instant portability across tons of platforms.
\end_layout
\begin_layout Standard
In 2012, we would argue that portability has never been more relevant.
There are three major operating systems on the desktop, two major smart
phone platforms, and three gaming consoles.
If your system is implemented with software rendering, your implementation
can run on all systems supported by the frontend, without writing any platform
specific code.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
In the case of
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch these are currently:
\end_layout
\begin_layout Itemize
Windows
\end_layout
\begin_layout Itemize
Linux
\end_layout
\begin_layout Itemize
OSX
\end_layout
\begin_layout Itemize
GameCube
\end_layout
\begin_layout Itemize
PlayStation 3
\end_layout
\begin_layout Itemize
XBox 1
\end_layout
\begin_layout Itemize
XBox 360
\end_layout
\begin_layout Itemize
Wii
\end_layout
\begin_layout Itemize
Android
\end_layout
\begin_layout Section
Features
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch has been in development for about two years.
During this time, some features have shown to be quinessential to retro
gaming systems.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
Implementing the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro API correctly, these features can be utilized without any additional
work.
\end_layout
\begin_layout Subsection
Frame-by-frame rewind
\end_layout
\begin_layout Standard
A libretro implementation that implements serialization and unserialization
of internal state is able to transparently support rewind mechanics.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
While many emulators support coarse grained rewind,
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch supports rewind at the frame level, i.e., frames can be rewound
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
one frame at a time, similar to the indie-title
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Braid
\end_layout
\end_inset
Braid.
\end_layout
\begin_layout Subsection
\begin_inset Index idx
status open
\begin_layout Plain Layout
FFmpeg
\end_layout
\end_inset
FFmpeg lossless recording
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
RetroArch can utilize the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libavcodec
\end_layout
\end_inset
libavcodec library to encode video and audio output from a libretro implementati
on.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
The data is encoded losslessly, with
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
FLAC
\end_layout
\end_inset
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
FLAC as audio codec, and cutting-edge
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
H.264
\end_layout
\end_inset
H.264/RGB (libx264) encoding, with a fallback to FFV1 for older playback
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
systems that don't support the modern
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
H.264
\end_layout
\end_inset
H.264/RGB variant.
The recorder is multithreaded, and easily performs real-time.
\end_layout
\begin_layout Subsection
Advanced GPU shader support
\end_layout
\begin_layout Standard
Classic 2D games have the advantage that their video output is very flexible,
that is, it can be post- processed easily.
Before the advent of programmable GPUs, video filters had to be performed
on the main CPU, which cut directly into performance, and severely limited
the types of filters possible to acheive in real-time.
RetroArch aims to move this processing to the GPU by using shaders.
A vast amount of shader effects are written already, and the shader format
used is documented and implemented independently by other frontends as
well.
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch's shader support is more advanced than most emulators.
It supports an arbitrary amount of shader passes, look-up textures (borders),
scriptable shaders that can react dynamically to input or game content.
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch still supports use of traditional CPU filters, however, it should
be considered a fallback if GPU support is broken.
\end_layout
\begin_layout Subsection
Peer-to-peer netplay
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch supports two-player action over the network.
It employs a rollback technique that aims to hide latency as much as possible,
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
similar to the method employed by
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
GGPO
\end_layout
\end_inset
GGPO.
\end_layout
\begin_layout Standard
In addition to head-to-head multiplayer, a spectator mode is implemented.
This mode allows a host to live stream playback to several watchers in
real-time.
The bandwidth required for this mode is near- zero as only raw input data
is transferred over the network.
\end_layout
\begin_layout Subsection
Audio DSP plugins
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch supports plugins that allows post-processing of audio data, similar
to post-processing of video data.
It supports use of on-the-fly configurable plugins with aid of a GUI.
\end_layout
\begin_layout Section
Implementing the API
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
The
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro API consists of several functions outlined in libretro.h, found
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
in the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch source package.
A libretro implementation should be compiled into a dynamically loadable
executable (.dll/.so/.dylib) or a static library (.a/.lib) that exports all
the functions outlined in libretro.h.
These will be called by the frontend.
Implementations are designed to be single-instance, so global state is
allowed.
Should the frontend call these functions in wrong order, undefined behavior
occurs.
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
The API header is compatible with
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
C99
\end_layout
\end_inset
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
C99 and
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
C++
\end_layout
\end_inset
C++.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
From
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
C99
\end_layout
\end_inset
C99, the bool type and <stdint.h> are used.
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
The program flow of a frontend using the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro API can be expressed as follows:
\end_layout
\begin_layout Subsection
Startup
\end_layout
\begin_layout Subsubsection
retro_api_version()
\end_layout
\begin_layout Standard
This function should return RETRO_API_VERSION, defined in libretro.h.
It is used by the frontend to determine if ABI/API are mismatched.
The version will be bumped should there be any non- compatible changes
to the API.
Changes to retro_* structures, as well as changes in publically visible
functions and/or their arguments will warrant a bump in API version.
\end_layout
\begin_layout Subsubsection
retro_init()
\end_layout
\begin_layout Standard
This function is called once, and gives the implementation a chance to initializ
e data structures.
This is sometimes implemented as a no-op.
\end_layout
\begin_layout Subsubsection
retro_set_*()
\end_layout
\begin_layout Standard
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
Libretro is callback based.
The frontend will set all callbacks at this stage, and the implementation
must store these function pointers somewhere.
The frontend can, at a later stage, call these.
\end_layout
\begin_layout Subsubsection
Environment callback
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
While
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro has callbacks for video, audio and input, there's a callback type
dubbed the environment callback.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
This callback (retro_environment_t) is a generic way for the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro implementation to access features of the API that are considered
too obscure to deserve its own symbols.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
It can be extended without breaking
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
ABI
\end_layout
\end_inset
ABI.
The callback has a return type of bool which tells if the frontend recognized
the request given to it.
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
Most implementations of
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro will not use this callback at all.
\end_layout
\begin_layout Subsubsection
retro_set_controller_port_device()
\end_layout
\begin_layout Standard
By default, joypads will be assumed to be inserted into the implementation.
If the engine is sensitive to which type of input device is plugged in,
the frontend may call this function to set the device to be used for a
certain player.
The implementation should try to auto-detect this if possible.
\end_layout
\begin_layout Subsubsection
retro_get_system_info()
\end_layout
\begin_layout Standard
The frontend will typically request statically known information about the
core such as the name of the implementation, version number, etc.
The information returned should be stored statically.
If dynamic allocation must take place, the implementation must make sure
to free this storage in retro_deinit() later.
\end_layout
\begin_layout Subsubsection
retro_load_game()
\end_layout
\begin_layout Standard
This function will load a ROM that the implementation will use to play the
game.
If the implementation is an emulator, this would be a game ROM image, if
it is a game engine, this could be packaged upassets for the game, etc.
The function takes a structure that points to the path where the ROM was
loaded from, as well as a memory chunk of the already loaded file.
\end_layout
\begin_layout Standard
There are two modes of loading files with libretro.
If the game engine requires to know the path of where the ROM image was
loaded from, the need_fullpath field in retro_system_info must be set to
true.
If the path is required, the frontend will not load the file into the data/size
fields, and it is up to the implementation to load the file from disk.
The path might be both relative and absolute, and the implementation must
check for both cases.
\end_layout
\begin_layout Standard
This is useful if the ROM image is too large to load into memory at once.
It is also useful if the assests consist of many smaller files, where it
is necessary to know the path of a master file to infer the paths of the
others.
If need_fullpath is set to false, the frontend will load the ROM image
into memory beforehand.
In this mode, the path field is not guaranteed to be non-NULL.
It should point to a valid path if the file was indeed, loaded from disk,
however, it is possible that the file was loaded from stdin, or similar,
which has no well-defined path.
\end_layout
\begin_layout Standard
It is recommended that need_fullpath is set to false if possible, as it
allows more features, such as soft- patching to work correctly.
\end_layout
\begin_layout Standard
retro_load_game_special() is a special case of retro_load_game().
It is designed to allow the loading of several ROMs together.
This is needed for certain odd cases like Super Nintendo with e.g.
Super GameBoy, Sufami Turbo, etc that consist of a "BIOS" + Game(s).
The function takes the type of game as an argument, and if a new game type
is to be added, it needs to be reserved in the libretro.h header.
Almost any libretro implementations should simply implement this as return
false;.
If a game consist of many smaller files it is encouraged to load a single
zipped file, or something similar.
\end_layout
\begin_layout Standard
Each ROM image can take an optional meta-argument, a string that gives extra
metadeta to the implementation.
The metadata is implementation specific, and can be ignored completely
in almost any implementation.
\end_layout
\begin_layout Subsubsection
retro_get_system_av_info()
\end_layout
\begin_layout Standard
This function lets the frontend know essential audio/video properties of
the game.
As this information can depend on the game being loaded, this info will
only be queried after a valid ROM image has been loaded.
It is important to accuractely report FPS and audio sampling rates, as
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
FFmpeg
\end_layout
\end_inset
FFmpeg recording relies on exact information to be able to run in sync for
several hours.
\end_layout
\begin_layout Subsection
Running
\end_layout
\begin_layout Subsubsection
retro_run()
\end_layout
\begin_layout Standard
After a game has been loaded successfully, retro_run() will be called repeatedly
as long as the user desires.
When called, the implementation will perform its inner functionality for
one video frame.
During this time, the implementation is free to call callbacks for video
frames, audio samples, as well as polling input, and querying current input
state.
The requirements for the callbacks are that video callback is called exactly
once, i.e.
it does not have to come last.
Also, input polling must be called at least once.
\end_layout
\begin_layout Subsubsection
Video/Audio synchronization considerations
\end_layout
\begin_layout Standard
Libretro is based on fixed rates.
Video FPS and audio sampling rates are always assumed to be constant.
Frontends will have control of the speed of playing, typically using VSync
to obtain correctspeed.
The frontend is free to "fast-forward", i.e.
play as fast as possible without waiting, or slow- motion.
For this reason, the engine should not rely on system timers to perform
arbitrary synchronization.
This is common and often needed in 3D games to account for varying frame
rates while still maintaining a playable game.
However, libretro targets classic systems where one can assume that 100
% real-time performance will always be met, thus avoiding the need for
careful timing code.
\end_layout
\begin_layout Standard
By default, the libretro implementation should replace any arbitrary sleep()/tim
e() patterns with simply calling video/audio callbacks.
The frontend will make sure to apply the proper synchronization.
\end_layout
\begin_layout Standard
This is mostly a problem with game ports, such as PrBoom.
For the libretro port of PrBoom, which heavily relied on timers and sleeping
patterns, sleeping was replaced with simply running for one frame, and
calling the video callback.
After that, enough audio was rendered to correspond to one frames worth
of time, 1 / fps seconds.
All sleeping and timing patterns could be removed, and synchronization
was correct.
\end_layout
\begin_layout Subsubsection
Audio callback considerations
\end_layout
\begin_layout Standard
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
The
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
libretro
\end_layout
\end_inset
libretro API has two different audio callbacks.
Only one of these should be used; the implementation must choose which
callback is best suited.
\end_layout
\begin_layout Standard
The first audio callback is per-sample, and has the type void (*)(int16_t,
int16_t).
This should be used if the implementation outputs audio on a per-sample
basis.
The frontend will make sure to partition the audio data into suitable chunks
to avoid incurring too much syscall overhead.
\end_layout
\begin_layout Standard
If audio is output in a "batch" fashion, i.e.
1 / fps seconds worth of audio data at a time, the batch approach should
be considered.
Rather than looping over all samples and calling per-sample callback every
time, the batch callback should be used instead, size_t (*)(const int16_t
*, size_t).
\end_layout
\begin_layout Standard
Using the batch callback, audio will not be copied in a temporary buffer,
which can buy a slight performance gain.
Also, all data will be pushed to audio driver in one go, saving some slight
overhead.
It is not recommended to use the batch callback for very small (< 32 frames)
amounts of data.
\end_layout
\begin_layout Standard
The data passed to the batch callback should, if possible, be aligned to
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
16 bytes (depends on platform), to allow accelerated
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
SIMD
\end_layout
\end_inset
SIMD operations on audio.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
RetroArch implements
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
SSE
\end_layout
\end_inset
SSE/
\begin_inset Index idx
status open
\begin_layout Plain Layout
AltiVec
\end_layout
\end_inset
AltiVec optimized audio processing for conversions and resampling.
\end_layout
\begin_layout Subsubsection
Input device abstraction
\end_layout
\begin_layout Standard
Abstracting input devices is the hardest part of defining a multi-system
API as it differs across every system.
The common input devices are:
\end_layout
\begin_layout Itemize
Joypad (with or without analogs)
\end_layout
\begin_layout Itemize
Mouse (e.g.
SNES mouse)
\end_layout
\begin_layout Itemize
Keyboard (e.g.
Commodore, Amiga)
\end_layout
\begin_layout Itemize
Lightguns (e.g.
SNES SuperScope)
\end_layout
\begin_layout Standard
The joypad abstraction is the most interesting.
Rather than complicating things by mapping input arbitrarily in terms of
the implementation, which would make input configuration very complex with
careful configuration on a per-implementation basis, an abstract joypad
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
device, the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Input device abstractions!RetroPad
\end_layout
\end_inset
RetroPad, was devised.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\end_layout
\begin_layout Standard
This joypad is essentially the Super Nintendo controller, widely considered
the pinnacle of retro game controllers.
To account for more modern systems with additional buttons, additions from
the PlayStation DualShock are incorporated, with extra shoulder buttons
(L2/R2), as well as depressable analogs (L3/R3).
In addition, the RETRO_DEVICE_ANALOG is used for analog stick data.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
An implementation should map its idea of a joypad in terms of the
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
Input device abstractions!RetroPad
\end_layout
\end_inset
RetroPad, which is what most users will have to use with their frontend.
\end_layout
\begin_layout Subsubsection
retro_serialize_size()
\end_layout
\begin_layout Subsubsection
retro_serialize()
\end_layout
\begin_layout Subsubsection
retro_unserialize()
\end_layout
\begin_layout Standard
Serialization is optional to implement.
Serialization is better known as "save states" in emulators, and these
functions are certainly more useful in emulators which have a fixed amount
of state.
It allows the frontend to take a snapshot of all internal state, and later
restore it.
This functionality is used to implement e.g.
rewind and netplay.
Some important considerations must be taken to implement these functions
well.
\end_layout
\begin_layout Standard
If serialization is not supported, retro_serialize_size() should return
0.
If retro_serialize_size() returns non-zero, it is assumed that serialization
is properly implemented.
\end_layout
\begin_layout Standard
The frontend should call retro_serialize_size() before calling retro_serialize()
to determine the amount of memory needed to correctly serialize.
The size eventually passed to retro_serialize() must be at least the size
of the value returned in retro_serialize_size().
If too large a buffer is passed to retro_serialize(), the extra data should
be ignored (or memset to 0).
\end_layout
\begin_layout Standard
It is valid for the value returned by retro_serialize_size() to vary over
time, however, it cannot ever increase over time.
If it should ever change, it must decrease.
This is rationaled by the ability to pre- determined a fixed save state
size right after retro_load_game() that will always be large enough to
hold any following serialization.
This certainty is fundamental to the rewind implementation.
This requirement only holds between calls to retro_load_game() and retro_unload
_game().
\end_layout
\begin_layout Standard
If possible, the implementation should attempt to serialize data at consistent
offsets in the memory buffer.
Delete trailing whitespace In #526 I accidentally lost some of my edits trying to selectively stage lines with typo fixes, while deleting hunks that were only whitespace changes. In hopes nobody else falls into this trap, I ran the following command to find all the files to edit, and apply emacs's delete-trailing-whitespace function to each file. ```sh find * -type f -print0 | xargs -0 -P$(nproc) -n1 -I{} sh -c 'if file -b "{}" | grep -qFi text; then emacs -batch "{}" -f delete-trailing-whitespace -f save-buffer; fi' ``` Note: `git add -u` will add only known paths to the stage (index), even if `tidy.sh` exists in the git work directory.
2020-07-20 05:48:57 +00:00
This will greatly help the rewind implementation in
add tex/lyx original versions of archival PDFs (#227) * restore underscore, update OpenGL dev links * add tex/lyx versions of archival documentation * restore underscore, update OpenGL dev links (#223) * organize development docs TOC / add git file format directives (#222) * organize developer TOC * add git file format metadata/directives * add "skeletor" to core dev doc; refactor text * add Vectrexia development guide to core dev docs * sort compilation guide TOC into cores and frontend
2019-02-19 17:39:49 +00:00
\begin_inset Index idx
status open
\begin_layout Plain Layout
RetroArch
\end_layout
\end_inset
RetroArch to use less memory.
\end_layout
\begin_layout Standard
Both retro_serialize() and retro_unserialize() return a boolean value to
let the frontend know if the implementation succeeded in serializing or
unserializing.
\end_layout
\begin_layout Subsection
Tear-down
\end_layout
\begin_layout Subsubsection
retro_unload_game()
\end_layout
\begin_layout Standard
After the user desired to stop playing, retro_unload_game() will be called.
This should free any internal data related to the game, and allow retro_load_ga
me() to be called again.
\end_layout
\begin_layout Subsubsection
retro_deinit()
\end_layout
\begin_layout Standard
This function should free all state that was initialized during retro_init().
After calling this function, the frontend can again call retro_init().
\end_layout
\begin_layout Standard
\begin_inset CommandInset index_print
LatexCommand printindex
type "idx"
\end_inset
\end_layout
\end_body
\end_document
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