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libfreerdp-codec: optimize zgfx history buffer wrap around

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This commit is contained in:
Marc-André Moreau
2014-06-05 18:09:37 -04:00
parent b4ba2c7a38
commit 77c3de47d7
1 changed files with 110 additions and 43 deletions
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153
libfreerdp/codec/zgfx.c
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@@ -27,6 +27,16 @@
#include <freerdp/codec/zgfx.h>
/**
* RDP8 Compressor Limits:
*
* Maximum number of uncompressed bytes in a single segment: 65535
* Maximum match distance / minimum history size: 2500000 bytes.
* Maximum number of segments: 65535
* Maximum expansion of a segment (when compressed size exceeds uncompressed): 1000 bytes
* Minimum match length: 3 bytes
*/
struct _ZGFX_TOKEN
{
int prefixLength;
@@ -95,6 +105,89 @@ static const ZGFX_TOKEN ZGFX_TOKEN_TABLE[] =
_zgfx->bits = _zgfx->BitsCurrent >> _zgfx->cBitsCurrent; \
_zgfx->BitsCurrent &= ((1 << _zgfx->cBitsCurrent) - 1);
void zgfx_history_buffer_ring_write(ZGFX_CONTEXT* zgfx, BYTE* src, UINT32 count)
{
UINT32 front;
UINT32 residue;
if (count <= 0)
return;
if (count > zgfx->HistoryBufferSize)
{
residue = count - zgfx->HistoryBufferSize;
count = zgfx->HistoryBufferSize;
src += residue;
zgfx->HistoryIndex = (zgfx->HistoryIndex + residue) % zgfx->HistoryBufferSize;
}
if (zgfx->HistoryIndex + count <= zgfx->HistoryBufferSize)
{
CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, count);
if ((zgfx->HistoryIndex += count) == zgfx->HistoryBufferSize)
zgfx->HistoryIndex = 0;
}
else
{
front = zgfx->HistoryBufferSize - zgfx->HistoryIndex;
CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, front);
CopyMemory(zgfx->HistoryBuffer, &src[front], count - front);
zgfx->HistoryIndex = count - front;
}
}
void zgfx_history_buffer_ring_read(ZGFX_CONTEXT* zgfx, int offset, BYTE* dst, UINT32 count)
{
UINT32 front;
UINT32 index;
UINT32 bytes;
UINT32 valid;
UINT32 bytesLeft;
BYTE* dptr = dst;
BYTE* origDst = dst;
if (count <= 0)
return;
bytesLeft = count;
index = (zgfx->HistoryIndex + zgfx->HistoryBufferSize - offset) % zgfx->HistoryBufferSize;
bytes = MIN(bytesLeft, offset);
if ((index + bytes) <= zgfx->HistoryBufferSize)
{
CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), bytes);
}
else
{
front = zgfx->HistoryBufferSize - index;
CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), front);
CopyMemory(&dptr[front], zgfx->HistoryBuffer, bytes - front);
}
if ((bytesLeft -= bytes) == 0)
return;
dptr += bytes;
valid = bytes;
do
{
bytes = valid;
if (bytes > bytesLeft)
bytes = bytesLeft;
CopyMemory(dptr, origDst, bytes);
dptr += bytes;
valid <<= 1;
}
while ((bytesLeft -= bytes) > 0);
}
int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegment)
{
BYTE c;
@@ -103,10 +196,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
int opIndex;
int haveBits;
int inPrefix;
UINT32 raw;
UINT32 count;
UINT32 distance;
UINT32 prevIndex;
if (cbSegment < 1)
return -1;
@@ -120,17 +211,9 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
if (!(flags & PACKET_COMPRESSED))
{
for (raw = 0; raw < cbSegment; raw++)
{
c = pbSegment[raw];
zgfx->HistoryBuffer[zgfx->HistoryIndex++] = c;
if (zgfx->HistoryIndex == zgfx->HistoryBufferSize)
zgfx->HistoryIndex = 0;
zgfx->OutputBuffer[zgfx->OutputCount++] = c;
}
zgfx_history_buffer_ring_write(zgfx, pbSegment, cbSegment);
CopyMemory(zgfx->OutputBuffer, pbSegment, cbSegment);
zgfx->OutputCount = cbSegment;
return 1;
}
@@ -161,6 +244,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
{
if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
{
/* Literal */
zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
c = (BYTE) (ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);
@@ -178,6 +263,8 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
if (distance != 0)
{
/* Match */
zgfx_GetBits(zgfx, 1);
if (zgfx->bits == 0)
@@ -203,27 +290,14 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
count += zgfx->bits;
}
prevIndex = zgfx->HistoryIndex + zgfx->HistoryBufferSize - distance;
prevIndex = prevIndex % zgfx->HistoryBufferSize;
while (count--)
{
c = zgfx->HistoryBuffer[prevIndex];
if (++prevIndex == zgfx->HistoryBufferSize)
prevIndex = 0;
zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;
if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
zgfx->HistoryIndex = 0;
zgfx->OutputBuffer[zgfx->OutputCount] = c;
++zgfx->OutputCount;
}
zgfx_history_buffer_ring_read(zgfx, distance, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
zgfx_history_buffer_ring_write(zgfx, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
zgfx->OutputCount += count;
}
else
{
/* Unencoded */
zgfx_GetBits(zgfx, 15);
count = zgfx->bits;
@@ -231,19 +305,12 @@ int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegmen
zgfx->cBitsCurrent = 0;
zgfx->BitsCurrent = 0;
while (count--)
{
c = *zgfx->pbInputCurrent++;
zgfx->cBitsRemaining -= 8;
CopyMemory(&(zgfx->OutputBuffer[zgfx->OutputCount]), zgfx->pbInputCurrent, count);
zgfx_history_buffer_ring_write(zgfx, zgfx->pbInputCurrent, count);
zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;
if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
zgfx->HistoryIndex = 0;
zgfx->OutputBuffer[zgfx->OutputCount] = c;
++zgfx->OutputCount;
}
zgfx->pbInputCurrent += count;
zgfx->cBitsRemaining -= (8 * count);
zgfx->OutputCount += count;
}
}