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85 lines
3.4 KiB
Plaintext
85 lines
3.4 KiB
Plaintext
***** Important notice ********************************************************
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This document describes the snapshot file format for Snes9x 1.52 and later,
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not compatible with 1.51.
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*******************************************************************************
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Snes9x snapshot file format: (may be gzip-compressed)
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Begins with fixed length signature, consisting of a string, ':', a 4-digit
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decimal version, and a '\n'.
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#!s9xsnp:0006 <-- '\n' after the 6
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Then we have various blocks. The block format is: 3-character block name,
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':', 6-digit length, ':', then the data. Blocks are written in a defined
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order. Structs are written packed with their members in a defined order, in
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big-endian order where applicable.
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NAM:000019:Chrono Trigger.zip
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Currently defined blocks (in order) are:
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Essential parts:
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NAM - ROM filename, from Memory.ROMFilename. 0-terminated string.
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CPU - struct SCPUState, CPU internal state variables.
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REG - struct SRegisters, emulated CPU registers.
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PPU - struct SPPU, PPU internal variables. Note that IPPU is never saved.
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DMA - struct SDMA, DMA/HDMA state variables.
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VRA - Memory.VRAM, 0x10000 bytes.
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RAM - Memory.RAM, 0x20000 bytes (WRAM).
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SRA - Memory.SRAM, 0x20000 bytes.
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FIL - Memory.FillRAM, 0x8000 bytes (register backing store).
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SND - All of sound emulated registers and state valiables.
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CTL - struct SControlSnapshot, controller emulation.
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TIM - struct STimings, variables about timings between emulated events.
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Optional parts:
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SFX - struct FxRegs_s, Super FX.
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SA1 - struct SSA1, SA1 internal state variables.
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SAR - struct SSA1Registers, SA1 emulated registers.
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DP1 - struct SDSP1, DSP-1.
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DP2 - struct SDSP2, DSP-2.
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DP4 - struct SDSP4, DSP-4.
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CX4 - Memory.C4RAM, 0x2000 bytes.
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ST0 - struct SST010, ST-010.
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OBC - struct SOBC1, OBC1 internal state variables.
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OBM - Memory.OBC1RAM, 0x2000 byts.
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S71 - struct SSPC7110Snapshot, SPC7110.
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SRT - struct SSRTCSnapshot, S-RTC internal state variables.
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CLK - struct SRTCData, S-RTC emulated registers.
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BSX - struct SBSX, BS-X.
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SHO - rendered SNES screen.
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MOV - struct SnapshotMovieInfo.
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MID - Some block of data the movie subsystem.
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==================
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Without changing the snapshot version number:
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---------------------------------------------
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Blocks may be safely added at the END of the file, as anything after the last
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block is ignored. Blocks may not be moved or removed.
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Blocks may not decrease in size. Say you decrease from 10 bytes to 5. Then
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later you increase back to 8. The only way you could safely do this is if
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bytes 5-7 still mean the same thing they meant when the block was 10 bytes
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long.
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Blocks may increase in size as you wish, as long as you can handle old
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savestates with the old shorter size.
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Struct members may not change in interpretation. New struct members may be
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added (at the END!) only if you can cope with them being binary-0 in older
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savestates. Struct members may not be removed or changed in size/type.
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With changing the snapshot version number:
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------------------------------------------
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Blocks may be added, moved, or removed at will.
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Blocks may decrease in size.
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Struct members may be added, moved, or deleted, and their
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interpretations/types may be changed. Use the 'debuted_in' and 'deleted_in'
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fields to indicate when the new member debuted or the old member went away.
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