Shipwright/soh/src/boot/yaz0.c
M4xw 39cc86c260 git subrepo clone https://github.com/HarbourMasters/soh.git
subrepo:
  subdir:   "soh"
  merged:   "ba904bbd0"
upstream:
  origin:   "https://github.com/HarbourMasters/soh.git"
  branch:   "master"
  commit:   "ba904bbd0"
git-subrepo:
  version:  "0.4.1"
  origin:   "???"
  commit:   "???"
2022-03-22 02:51:23 +01:00

103 lines
2.7 KiB
C

#include "global.h"
#include <string.h>
u8 sYaz0DataBuffer[0x400];
uintptr_t sYaz0CurDataEnd;
uintptr_t sYaz0CurRomStart;
u32 sYaz0CurSize;
uintptr_t sYaz0MaxPtr;
void* Yaz0_FirstDMA(void) {
u32 pad0;
u32 pad1;
u32 dmaSize;
u32 curSize;
sYaz0MaxPtr = sYaz0CurDataEnd - 0x19;
curSize = sYaz0CurDataEnd - (uintptr_t)sYaz0DataBuffer;
dmaSize = (curSize > sYaz0CurSize) ? sYaz0CurSize : curSize;
DmaMgr_DmaRomToRam(sYaz0CurRomStart, sYaz0DataBuffer, dmaSize);
sYaz0CurRomStart += dmaSize;
sYaz0CurSize -= dmaSize;
return sYaz0DataBuffer;
}
void* Yaz0_NextDMA(void* curSrcPos) {
u8* dst;
u32 restSize;
u32 dmaSize;
restSize = sYaz0CurDataEnd - (uintptr_t)curSrcPos;
dst = (restSize & 7) ? (sYaz0DataBuffer - (restSize & 7)) + 8 : sYaz0DataBuffer;
memcpy(dst, curSrcPos, restSize);
dmaSize = (sYaz0CurDataEnd - (uintptr_t)dst) - restSize;
if (sYaz0CurSize < dmaSize) {
dmaSize = sYaz0CurSize;
}
if (dmaSize != 0) {
DmaMgr_DmaRomToRam(sYaz0CurRomStart, (uintptr_t)dst + restSize, dmaSize);
sYaz0CurRomStart += dmaSize;
sYaz0CurSize -= dmaSize;
if (!sYaz0CurSize) {
sYaz0MaxPtr = (uintptr_t)dst + restSize + dmaSize;
}
}
return dst;
}
void Yaz0_DecompressImpl(Yaz0Header* hdr, u8* dst) {
u32 bitIdx = 0;
u8* src = (u8*)hdr->data;
u8* dstEnd = dst + hdr->decSize;
u32 chunkHeader;
u32 nibble;
u8* backPtr;
u32 chunkSize;
u32 off;
do {
if (bitIdx == 0) {
if ((sYaz0MaxPtr < (uintptr_t)src) && (sYaz0CurSize != 0)) {
src = Yaz0_NextDMA(src);
}
chunkHeader = *src++;
bitIdx = 8;
}
if (chunkHeader & (1 << 7)) { // uncompressed
*dst = *src;
dst++;
src++;
} else { // compressed
off = ((*src & 0xF) << 8 | *(src + 1));
nibble = *src >> 4;
backPtr = dst - off;
src += 2;
chunkSize = (nibble == 0) // N = chunkSize; B = back offset
? (u32)(*src++ + 0x12) // 3 bytes 0B BB NN
: nibble + 2; // 2 bytes NB BB
do {
*dst++ = *(backPtr++ - 1);
chunkSize--;
} while (chunkSize != 0);
}
chunkHeader <<= 1;
bitIdx--;
} while (dst != dstEnd);
}
void Yaz0_Decompress(uintptr_t romStart, void* dst, size_t size) {
sYaz0CurRomStart = romStart;
sYaz0CurSize = size;
sYaz0CurDataEnd = sYaz0DataBuffer + sizeof(sYaz0DataBuffer);
Yaz0_DecompressImpl(Yaz0_FirstDMA(), dst);
}