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libwinpr-utils: basic working UINT32-based bitstream implementation

This commit is contained in:
Marc-André Moreau 2014-03-05 12:56:26 -05:00
parent 3973775b69
commit 3ba1d1ff4e
2 changed files with 40 additions and 20 deletions
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3
winpr/include/winpr/collections.h
View File

@ -602,10 +602,11 @@ struct _wBitStream
{
BYTE* buffer;
BYTE* pointer;
DWORD boffset;
DWORD position;
DWORD length;
DWORD capacity;
UINT32 offset;
UINT32 accumulator;
};
typedef struct _wBitStream wBitStream;

57
winpr/libwinpr/utils/test/TestBitStream.c
View File

@ -212,36 +212,41 @@ void BitDump(BYTE* buffer, DWORD length, BOOL msbFirst)
void BitStream_Attach(wBitStream* bs, BYTE* buffer, DWORD capacity)
{
bs->boffset = 0;
bs->position = 0;
bs->buffer = buffer;
bs->offset = 0;
bs->accumulator = 0;
bs->pointer = bs->buffer;
bs->capacity = capacity;
bs->length = bs->capacity;
}
void BitStream_Flush(wBitStream* bs)
{
*(bs->pointer + 0) = (bs->accumulator >> 0);
*(bs->pointer + 1) = (bs->accumulator >> 8);
*(bs->pointer + 2) = (bs->accumulator >> 16);
*(bs->pointer + 3) = (bs->accumulator >> 24);
}
void BitStream_Write_Bits(wBitStream* bs, UINT32 bits, UINT32 nbits)
{
while ((bs->boffset + nbits) >= 8)
{
*(bs->pointer) |= (bits << bs->boffset);
bs->position += (8 - bs->boffset);
nbits -= (8 - bs->boffset);
bs->boffset = 0;
bs->pointer++;
}
bs->accumulator |= (bits << bs->offset);
bs->position += nbits;
bs->offset += nbits;
if (nbits)
if (bs->offset >= 32)
{
*(bs->pointer) |= (bits << bs->boffset);
bs->position += nbits;
bs->boffset += nbits;
*(bs->pointer + 0) = (bs->accumulator >> 0);
*(bs->pointer + 1) = (bs->accumulator >> 8);
*(bs->pointer + 2) = (bs->accumulator >> 16);
*(bs->pointer + 3) = (bs->accumulator >> 24);
if (bs->boffset >= 8)
{
bs->boffset = bs->boffset % 8;
bs->pointer++;
}
bs->offset = bs->offset - 32;
bs->accumulator = bits >> (nbits - bs->offset);
bs->pointer += 4;
}
}
@ -260,15 +265,29 @@ int TestBitStream(int argc, char* argv[])
BitStream_Write_Bits(bs, 0xF, 4); /* 1111 */
BitStream_Write_Bits(bs, 0xA, 4); /* 0101 */
BitStream_Flush(bs);
BitDump(buffer, bs->position, TRUE);
BitStream_Write_Bits(bs, 3, 2); /* 11 */
BitStream_Write_Bits(bs, 0, 3); /* 000 */
BitStream_Write_Bits(bs, 0x2D, 6); /* 101101 */
BitStream_Write_Bits(bs, 0x19, 5); /* 11001 */
//BitStream_Flush(bs); /* flush should be done automatically here (32 bits written) */
BitDump(buffer, bs->position, TRUE);
BitStream_Write_Bits(bs, 0xAF0A, 16);
BitStream_Write_Bits(bs, 3, 2); /* 11 */
BitStream_Flush(bs);
BitDump(buffer, bs->position, TRUE);
BitStream_Write_Bits(bs, 00, 2); /* 00 */
BitStream_Write_Bits(bs, 0xF, 4); /* 1111 */
BitStream_Write_Bits(bs, 0, 20);
BitStream_Write_Bits(bs, 0xAFF, 12); /* 111111110101 */
BitStream_Flush(bs);
BitDump(buffer, bs->position, TRUE);
BitStream_Free(bs);