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libfreerdp-codec: add xcrush rolling hash chunker

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This commit is contained in:
Marc-André Moreau 2014-05-21 22:55:45 -04:00
parent 4bac8374de
commit fd23b2f041
2 changed files with 133 additions and 1 deletions
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11
include/freerdp/codec/xcrush.h
View File

@ -25,6 +25,13 @@
#include <freerdp/codec/mppc.h>
struct _XCRUSH_SIGNATURE
{
UINT16 seed;
UINT16 size;
};
typedef struct _XCRUSH_SIGNATURE XCRUSH_SIGNATURE;
struct _RDP61_MATCH_DETAILS
{
UINT16 MatchLength;
@ -52,6 +59,10 @@ struct _XCRUSH_CONTEXT
UINT32 HistoryBufferSize;
BYTE HistoryBuffer[2000000];
BYTE BlockBuffer[16384];
UINT32 SignatureIndex;
UINT32 SignatureCount;
XCRUSH_SIGNATURE* Signatures;
};
typedef struct _XCRUSH_CONTEXT XCRUSH_CONTEXT;

123
libfreerdp/codec/xcrush.c
View File

@ -27,6 +27,126 @@
#include <freerdp/codec/xcrush.h>
#ifndef _rotl
INLINE UINT32 _rotl(UINT32 x, UINT32 r) {
return (x << r) | (x >> (32 - r));
}
#endif
UINT32 xcrush_update_hash(BYTE* data, UINT32 size)
{
BYTE* end;
UINT32 seed = 5381; /* same value as in djb2 */
if (size > 32)
{
size = 32;
seed = 5413;
}
end = &data[size - 4];
while (data < end)
{
seed += (data[3] ^ data[0]) + (data[1] << 8);
data += 4;
}
return seed;
}
int xcrush_append_chunk(XCRUSH_CONTEXT* xcrush, BYTE* data, UINT32* beg, UINT32 end)
{
UINT16 seed;
UINT32 size;
if (xcrush->SignatureIndex >= xcrush->SignatureCount)
return 0;
size = end - *beg;
if (size > 0xFFFF)
return 0;
if (size >= 15)
{
seed = xcrush_update_hash(&data[*beg], size);
xcrush->Signatures[xcrush->SignatureIndex].size = size;
xcrush->Signatures[xcrush->SignatureIndex].seed = seed;
xcrush->SignatureIndex++;
*beg = end;
}
return 1;
}
char xcrush_compute_chunks(XCRUSH_CONTEXT* xcrush, BYTE* data, UINT32 size, XCRUSH_SIGNATURE* Signatures, UINT32 SignatureCount, UINT32* pIndex)
{
UINT32 i = 0;
UINT32 offset = 0;
UINT32 accumulator = 0;
*pIndex = 0;
xcrush->SignatureIndex = 0;
xcrush->Signatures = Signatures;
xcrush->SignatureCount = SignatureCount;
if (size < 128)
return 0;
for (i = 0; i < 32; i++)
{
accumulator = data[i] ^ _rotl(accumulator, 1);
}
for (i = 0; i < size - 64; i++)
{
accumulator = data[i + 32] ^ data[i] ^ _rotl(accumulator, 1);
if (!(accumulator & 0x7F))
{
if (!xcrush_append_chunk(xcrush, data, &offset, i + 32))
return 0;
}
i++;
accumulator = data[i + 32] ^ data[i] ^ _rotl(accumulator, 1);
if (!(accumulator & 0x7F))
{
if (!xcrush_append_chunk(xcrush, data, &offset, i + 32))
return 0;
}
i++;
accumulator = data[i + 32] ^ data[i] ^ _rotl(accumulator, 1);
if (!(accumulator & 0x7F))
{
if (!xcrush_append_chunk(xcrush, data, &offset, i + 32))
return 0;
}
i++;
accumulator = data[i + 32] ^ data[i] ^ _rotl(accumulator, 1);
if (!(accumulator & 0x7F))
{
if (!xcrush_append_chunk(xcrush, data, &offset, i + 32))
return 0;
}
}
if ((size == offset) || xcrush_append_chunk(xcrush, data, &offset, size))
{
*pIndex = xcrush->SignatureIndex;
return 1;
}
return 0;
}
int xcrush_copy_bytes(BYTE* dst, BYTE* src, int num)
{
int index;
@ -319,7 +439,8 @@ int xcrush_compress(XCRUSH_CONTEXT* xcrush, BYTE* pSrcData, UINT32 SrcSize, BYTE
void xcrush_context_reset(XCRUSH_CONTEXT* xcrush)
{
xcrush->SignatureIndex = 0;
xcrush->Signatures = NULL;
}
XCRUSH_CONTEXT* xcrush_context_new(BOOL Compressor)