mirror of
https://github.com/libretro/RetroArch.git
synced 2024-11-30 19:50:24 +00:00
121 lines
4.4 KiB
Plaintext
121 lines
4.4 KiB
Plaintext
Refer also to this page for more information -
|
|
https://docs.libretro.com/development/coding-standards/
|
|
|
|
Struct ordering
|
|
---------------
|
|
|
|
For POD-types, try to order structs as follows (first to last):
|
|
|
|
* long double (8 bytes, 16 bytes [64bit x86], 12 bytes [32bit x86])
|
|
* double (8 bytes)
|
|
* int64_t (8 bytes, 8 bytes [32bit ARM],
|
|
4 bytes [32bit x86])
|
|
* uint64_t (4 bytes [32bit], 8 bytes [32bit ARM], 8 bytes [64bit])
|
|
* pointer (4 bytes [32bit], 8 bytes [64bit] [1])
|
|
* intptr_t (4 bytes [32bit], 8 bytes [64bit] [1])
|
|
* uintptr_t (4 bytes [32bit], 8 bytes [64bit] [1])
|
|
* ptrdiff_t (4 bytes [32bit], 8 bytes [64bit] [1])
|
|
* ssize_t (4 bytes [32bit], 8 bytes [64bit])
|
|
* size_t (4 bytes [32bit], 8 bytes [64bit])
|
|
* jmp_buf (4 bytes)
|
|
* long (4 bytes [64bit Win], 8 bytes [64bit non-Win],
|
|
4 bytes [32bit])
|
|
* int32_t (4 bytes)
|
|
* unsigned (4 bytes)
|
|
* float (4 bytes)
|
|
* int (4 bytes)
|
|
* enum (4 bytes)
|
|
* int16_t (2 bytes)
|
|
* char (1 byte)
|
|
* bool (1 byte)
|
|
|
|
[1] PS3 uses 4 byte pointers despite having a 64bit processor
|
|
|
|
Struct members should be sorted by alignment. Therefore, structs
|
|
should be sorted by the largest type inside them.
|
|
|
|
For example, take a struct like this:
|
|
|
|
typedef struct
|
|
{
|
|
size_t capacity;
|
|
bool old_format;
|
|
bool compress;
|
|
bool fuzzy_archive_match;
|
|
bool autofix_paths;
|
|
char path[PATH_MAX_LENGTH];
|
|
char base_content_directory[PATH_MAX_LENGTH];
|
|
} playlist_config_t;
|
|
|
|
size_t has the biggest alignment here, so 'struct playlist_config_t'
|
|
inside a struct should come before or after size_t.
|
|
|
|
*** BEST PRACTICES ***
|
|
|
|
* If we have pointers and size variable pairs, it's best to
|
|
interleave them to increase the probability they go in the
|
|
same cacheline. It also makes the code more readable, that
|
|
these two variables are connected.
|
|
|
|
Example:
|
|
|
|
struct a
|
|
{
|
|
char* b;
|
|
size_t b_len;
|
|
char* c;
|
|
size_t c_len;
|
|
};
|
|
|
|
Stack size
|
|
----------
|
|
|
|
You have to assume that stack size is going to be limited in
|
|
RetroArch. Some game consoles (and other embedded systems)
|
|
might have a default stack size as low as 128Kb or less.
|
|
Be conservative with stack size but don't try to put very
|
|
small structs on heap either [to avoid memory fragmentation
|
|
among other things]. A balancing act here is necessary.
|
|
|
|
Be mindful that heap allocations are slow compared to stack.
|
|
|
|
Functions
|
|
---------
|
|
- Avoid doing small getter/setter functions. We want a function
|
|
to justify its function call overhead by doing a significant
|
|
body of work. Small one-line getter/setter functions for what
|
|
is predominantly C-style structs is not useful, plus it leads
|
|
to people thinking this function is more complex than it
|
|
actually is, thus obfuscating the sourcecode instead of it
|
|
being easier to read.
|
|
|
|
If you can find examples in the codebase that violate this
|
|
guideline, do not hesitate to point them out to us.
|
|
|
|
Variable declaration
|
|
--------------------
|
|
For C source files, we have to insist you stick to the following:
|
|
|
|
- Declare variables either at the start of a function or the start
|
|
of a code block, depending on the scope they need.
|
|
- Do not do initial for loop declarations. Refer to the bulletpoint above:
|
|
either declare them at the start of the function, or at the start
|
|
of the code block.
|
|
|
|
Not doing this would break compilation on platforms where we are compiling
|
|
these C source files in C89 compatibility mode. If such issues occur in pull
|
|
requests, we have to request that it be fixed.
|
|
|
|
VLA (Variable Length Array)
|
|
---------------------------
|
|
Do not use VLAs (Variable Length Array) in C source files. These are not
|
|
C89-compliant.
|
|
|
|
Miscellaneous
|
|
-------------
|
|
- Brace usage follows "Allman style". The brace associated with a control statement is placed on the following line,
|
|
indented to the same level as the control statement.
|
|
Statements within the braces are indented to the next level.
|
|
- A single statement block must not include brackets (unless the block uses a macro that expands into multiple lines)
|
|
- If possible, avoid 'while (true)' and use 'for (;;)' instead
|