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Implement basic LZ77 decompressing

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UnknownShadow200 2017-10-06 13:51:19 +11:00
parent 478d96328a
commit 24ca19efb9
1 changed files with 32 additions and 11 deletions
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43
src/Client/Deflate.c
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@ -155,7 +155,8 @@ void ZLibHeader_Read(Stream* s, ZLibHeader* header) {
#define DeflateState_CompressedLitRepeat 8 #define DeflateState_CompressedLitRepeat 8
#define DeflateState_CompressedDist 9 #define DeflateState_CompressedDist 9
#define DeflateState_CompressedDistRepeat 10 #define DeflateState_CompressedDistRepeat 10
#define DeflateState_Done 11 #define DeflateState_CompressedData 11
#define DeflateState_Done 12
/* Insert this byte into the bit buffer */ /* Insert this byte into the bit buffer */
#define DEFLATE_GET_BYTE(state)\ #define DEFLATE_GET_BYTE(state)\
@ -308,7 +309,6 @@ void Deflate_Init(DeflateState* state, Stream* source) {
} }
void Deflate_Process(DeflateState* state) { void Deflate_Process(DeflateState* state) {
/* TODO: Read input here */
for (;;) { for (;;) {
switch (state->State) { switch (state->State) {
case DeflateState_Header: { case DeflateState_Header: {
@ -377,10 +377,9 @@ void Deflate_Process(DeflateState* state) {
copyLen = min(copyLen, state->Index); copyLen = min(copyLen, state->Index);
if (copyLen > 0) { if (copyLen > 0) {
Platform_MemCpy(state->Output, state->Input, copyLen); Platform_MemCpy(state->Output, state->Input, copyLen);
/* TODO: Copy to window */ /* TODO: Copy output to window!!! */
state->Output += copyLen; state->Output += copyLen; state->AvailOut -= copyLen;
state->AvailIn -= copyLen; state->AvailIn -= copyLen;
state->AvailOut -= copyLen;
state->Index -= copyLen; state->Index -= copyLen;
} }
@ -486,8 +485,9 @@ void Deflate_Process(DeflateState* state) {
if (lit < 256) { if (lit < 256) {
if (lit == -1) return; if (lit == -1) return;
*state->Output = (UInt8)lit; *state->Output = (UInt8)lit;
state->Output++; state->Window[state->WindowIndex] = (UInt8)lit;
state->AvailOut--; state->Output++; state->AvailOut--;
state->WindowIndex = (state->WindowIndex + 1) & DEFLATE_WINDOW_MASK;
} else if (lit == 256) { } else if (lit == 256) {
state->State = DEFLATE_NEXTBLOCK_STATE(state); state->State = DEFLATE_NEXTBLOCK_STATE(state);
break; break;
@ -532,11 +532,31 @@ void Deflate_Process(DeflateState* state) {
UInt32 bits = dist_bits[distIdx]; UInt32 bits = dist_bits[distIdx];
DEFLATE_ENSURE_BITS(state, bits); DEFLATE_ENSURE_BITS(state, bits);
UInt32 dist = dist_base[distIdx] + DEFLATE_READ_BITS(state, bits); state->TmpDist = dist_base[distIdx] + DEFLATE_READ_BITS(state, bits);
state->State = DeflateState_CompressedLit; state->State = DeflateState_CompressedData;
break; }
}
case DeflateState_CompressedData: {
UInt32 len = (UInt32)state->TmpLit, dist = (UInt32)state->TmpDist;
len = min(len, state->AvailOut);
UInt32 startIdx = (state->WindowIndex - dist) & DEFLATE_WINDOW_MASK;
UInt32 i;
/* TODO: Should we test outside of the loop, whether a masking will be required or not? */
for (i = 0; i < len; i++) {
UInt8 value = state->Window[(startIdx + i) & DEFLATE_WINDOW_MASK];
*state->Output = value;
state->Window[state->WindowIndex] = value;
state->Output++; state->AvailOut--;
state->WindowIndex = (state->WindowIndex + 1) & DEFLATE_WINDOW_MASK;
}
/* In case LZ77 length is less than output length */
state->TmpLit -= len;
if (state->TmpLit == 0) state->State = DeflateState_CompressedLit;
break;
}
case DeflateState_Done: case DeflateState_Done:
return; return;
} }
@ -548,6 +568,7 @@ ReturnCode Deflate_StreamRead(Stream* stream, UInt8* data, UInt32 count, UInt32*
if (state->NextIn == DEFLATE_MAX_INPUT && state->AvailIn == 0) { if (state->NextIn == DEFLATE_MAX_INPUT && state->AvailIn == 0) {
state->NextIn = 0; state->NextIn = 0;
} }
/* TODO: Do the actual reading here.... */
state->Output = data; state->Output = data;
state->AvailOut = count; state->AvailOut = count;