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libfreerdp-codec: optimize zgfx bitstream

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This commit is contained in:
Marc-André Moreau
2014-06-05 15:41:42 -04:00
parent 4e86211f34
commit b4ba2c7a38
2 changed files with 28 additions and 39 deletions
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1
include/freerdp/codec/zgfx.h
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@@ -35,6 +35,7 @@ struct _ZGFX_CONTEXT
BYTE* pbInputCurrent;
BYTE* pbInputEnd;
UINT32 bits;
UINT32 cBitsRemaining;
UINT32 BitsCurrent;
UINT32 cBitsCurrent;

66
libfreerdp/codec/zgfx.c
View File

@@ -83,29 +83,17 @@ static const ZGFX_TOKEN ZGFX_TOKEN_TABLE[] =
{ 0 }
};
UINT32 zgfx_GetBits(ZGFX_CONTEXT* zgfx, UINT32 bitCount)
{
UINT32 result;
while (zgfx->cBitsCurrent < bitCount)
{
zgfx->BitsCurrent <<= 8;
if (zgfx->pbInputCurrent < zgfx->pbInputEnd)
zgfx->BitsCurrent += *(zgfx->pbInputCurrent)++;
zgfx->cBitsCurrent += 8;
}
zgfx->cBitsRemaining -= bitCount;
zgfx->cBitsCurrent -= bitCount;
result = zgfx->BitsCurrent >> zgfx->cBitsCurrent;
zgfx->BitsCurrent &= ((1 << zgfx->cBitsCurrent) - 1);
return result;
}
#define zgfx_GetBits(_zgfx, _nbits) \
while (_zgfx->cBitsCurrent < _nbits) { \
_zgfx->BitsCurrent <<= 8; \
if (_zgfx->pbInputCurrent < _zgfx->pbInputEnd) \
_zgfx->BitsCurrent += *(_zgfx->pbInputCurrent)++; \
_zgfx->cBitsCurrent += 8; \
} \
_zgfx->cBitsRemaining -= _nbits; \
_zgfx->cBitsCurrent -= _nbits; \
_zgfx->bits = _zgfx->BitsCurrent >> _zgfx->cBitsCurrent; \
_zgfx->BitsCurrent &= ((1 << _zgfx->cBitsCurrent) - 1);
int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegment)
{
@@ -116,7 +104,6 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
int haveBits;
int inPrefix;
UINT32 raw;
UINT32 bits;
UINT32 count;
UINT32 distance;
UINT32 prevIndex;
@@ -151,6 +138,7 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
zgfx->pbInputCurrent = pbSegment;
zgfx->pbInputEnd = &pbSegment[cbSegment - 1];
/* NumberOfBitsToDecode = ((NumberOfBytesToDecode - 1) * 8) - ValueOfLastByte */
zgfx->cBitsRemaining = 8 * (cbSegment - 1) - *zgfx->pbInputEnd;
zgfx->cBitsCurrent = 0;
zgfx->BitsCurrent = 0;
@@ -164,8 +152,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
{
while (haveBits < ZGFX_TOKEN_TABLE[opIndex].prefixLength)
{
bits = zgfx_GetBits(zgfx, 1);
inPrefix = (inPrefix << 1) + bits;
zgfx_GetBits(zgfx, 1);
inPrefix = (inPrefix << 1) + zgfx->bits;
haveBits++;
}
@@ -173,8 +161,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
{
if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
{
bits = zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
c = (BYTE) (ZGFX_TOKEN_TABLE[opIndex].valueBase + bits);
zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
c = (BYTE) (ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);
zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;
@@ -185,14 +173,14 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
}
else
{
bits = zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + bits;
zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits;
if (distance != 0)
{
bits = zgfx_GetBits(zgfx, 1);
zgfx_GetBits(zgfx, 1);
if (bits == 0)
if (zgfx->bits == 0)
{
count = 3;
}
@@ -201,18 +189,18 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
count = 4;
extra = 2;
bits = zgfx_GetBits(zgfx, 1);
zgfx_GetBits(zgfx, 1);
while (bits == 1)
while (zgfx->bits == 1)
{
count *= 2;
extra++;
bits = zgfx_GetBits(zgfx, 1);
zgfx_GetBits(zgfx, 1);
}
bits = zgfx_GetBits(zgfx, extra);
count += bits;
zgfx_GetBits(zgfx, extra);
count += zgfx->bits;
}
prevIndex = zgfx->HistoryIndex + zgfx->HistoryBufferSize - distance;
@@ -236,8 +224,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
}
else
{
bits = zgfx_GetBits(zgfx, 15);
count = bits;
zgfx_GetBits(zgfx, 15);
count = zgfx->bits;
zgfx->cBitsRemaining -= zgfx->cBitsCurrent;
zgfx->cBitsCurrent = 0;