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#include <global.h>
u8* sJpegBitStreamPtr;
u32 sJpegBitStreamByteIdx;
u8 sJpegBitStreamBitIdx;
u8 sJpegBitStreamDontSkip;
u32 sJpegBitStreamCurWord;
s32 JpegDecoder_Decode(JpegDecoder* decoder, u16* mcuBuff, s32 count, u8 isFollowing, JpegDecoderState* state) {
s16 pad;
s16 unk0;
s16 unk1;
s16 unk2;
u32 idx;
s32 inc;
s16 unkCount;
JpegHuffmanTable* hTable0;
JpegHuffmanTable* hTable1;
JpegHuffmanTable* hTable2;
JpegHuffmanTable* hTable3;
inc = 0;
sJpegBitStreamPtr = decoder->imageData;
if (decoder->mode == 0) {
unkCount = 2;
} else {
unkCount = 4;
if (decoder->unk_05 == 1) {
inc = 8 * 8 * 2;
}
}
hTable0 = decoder->hTablePtrs[0];
hTable1 = decoder->hTablePtrs[1];
hTable2 = decoder->hTablePtrs[2];
hTable3 = decoder->hTablePtrs[3];
if (!isFollowing) {
sJpegBitStreamByteIdx = 0;
sJpegBitStreamBitIdx = 32;
sJpegBitStreamCurWord = 0;
sJpegBitStreamDontSkip = 0;
unk0 = 0;
unk1 = 0;
unk2 = 0;
} else {
sJpegBitStreamByteIdx = state->byteIdx;
sJpegBitStreamBitIdx = state->bitIdx;
sJpegBitStreamCurWord = state->curWord;
sJpegBitStreamDontSkip = state->dontSkip;
unk0 = state->unk_0C;
unk1 = state->unk_0E;
unk2 = state->unk_10;
}
while (count != 0) {
for (idx = 0; idx < unkCount; idx++) {
if (JpegDecoder_ProcessMcu(hTable0, hTable1, mcuBuff, &unk0)) {
return 2;
}
mcuBuff += 8 * 8;
}
if (JpegDecoder_ProcessMcu(hTable2, hTable3, mcuBuff, &unk1)) {
return 2;
}
mcuBuff += 8 * 8;
if (JpegDecoder_ProcessMcu(hTable2, hTable3, mcuBuff, &unk2)) {
return 2;
}
count--;
mcuBuff += 8 * 8;
mcuBuff += inc;
}
state->byteIdx = sJpegBitStreamByteIdx;
state->bitIdx = sJpegBitStreamBitIdx;
state->curWord = sJpegBitStreamCurWord;
state->dontSkip = sJpegBitStreamDontSkip;
state->unk_0C = unk0;
state->unk_0E = unk1;
state->unk_10 = unk2;
return 0;
}
s32 JpegDecoder_ProcessMcu(JpegHuffmanTable* hTable0, JpegHuffmanTable* hTable1, s16* mcu, s16* unk) {
s8 i = 0;
s8 zeroCount;
s16 coeff;
if (JpegDecoder_ParseNextSymbol(hTable0, &coeff, &zeroCount)) {
return 1;
}
*unk += coeff;
mcu[i++] = *unk;
while (i < 8 * 8) {
if (JpegDecoder_ParseNextSymbol(hTable1, &coeff, &zeroCount) != 0) {
return 1;
}
if (coeff == 0) {
if (zeroCount == 0xF) {
while (zeroCount-- >= 0) {
mcu[i++] = 0;
}
} else {
while (i < 8 * 8) {
mcu[i++] = 0;
}
break;
}
} else {
while (0 < zeroCount--) {
mcu[i++] = 0;
}
mcu[i++] = coeff;
}
}
return 0;
}
#ifdef NON_MATCHING
// stack usage (coeffLength is stored as a u32 instead of a u8)
s32 JpegDecoder_ParseNextSymbol(JpegHuffmanTable* hTable, s16* outCoeff, u8* outZeroCount) {
u16 buff;
u8 codeIdx;
u8 sym;
u8 coeffLength; // 0x26
u16 codeOff; // 0x24
codeOff = 0;
buff = JpegDecoder_ReadBits(16);
for (codeIdx = 0; codeIdx < 16; codeIdx++) {
if (hTable->codesB[codeIdx] == 0xFFFF) {
continue;
}
codeOff = buff >> (15 - codeIdx);
if (codeOff <= hTable->codesB[codeIdx]) {
break;
}
}
if (codeIdx >= 16) {
return 1;
}
sym = hTable->symbols[hTable->codeOffs[codeIdx] + codeOff - hTable->codesA[codeIdx]];
*outZeroCount = sym >> 4;
coeffLength = sym & 0xF; // not using a temp for "sym & 0xF" puts coeffLength on the stack
sJpegBitStreamBitIdx += codeIdx - 15;
*outCoeff = 0;
if (coeffLength) { // (cond != 0) instead of (cond) puts coeffLength on the stack
*outCoeff = JpegDecoder_ReadBits(coeffLength);
if (*outCoeff < (1 << (coeffLength - 1))) {
*outCoeff +=
(-1 << coeffLength) + 1; // (*outCoeff -= (1 << coeffLength)-1; makes more sense but doesn't match)
}
}
return 0;
}
#else
#pragma GLOBAL_ASM("asm/non_matchings/code/jpegdecoder/JpegDecoder_ParseNextSymbol.s")
#endif
u16 JpegDecoder_ReadBits(u8 len) {
u8 byteCount;
u8 data;
s32 ret;
u32 temp;
ret = 0; // this is required for some reason
for (byteCount = sJpegBitStreamBitIdx >> 3; byteCount > 0; byteCount--) {
data = sJpegBitStreamPtr[sJpegBitStreamByteIdx++];
if (sJpegBitStreamDontSkip) {
if (data == 0) {
data = sJpegBitStreamPtr[sJpegBitStreamByteIdx++];
}
}
sJpegBitStreamDontSkip = (data == 0xFF) ? 1 : 0;
sJpegBitStreamCurWord <<= 8;
sJpegBitStreamCurWord |= data;
sJpegBitStreamBitIdx -= 8;
}
ret = (sJpegBitStreamCurWord << (sJpegBitStreamBitIdx));
temp = ret;
ret = temp >> -len;
sJpegBitStreamBitIdx += len;
return ret;
}
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