Take advantage of available input padding to optimize mszh_decomp
Originally committed as revision 19059 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -73,7 +73,7 @@ typedef struct LclDecContext {
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/**
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* \param srcptr compressed source buffer, must be padded with at least 4 extra bytes
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* \param srcptr compressed source buffer, must be padded with at least 5 extra bytes
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* \param destptr must be padded sufficiently for av_memcpy_backptr
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*/
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static unsigned int mszh_decomp(const unsigned char * srcptr, int srclen, unsigned char * destptr, unsigned int destsize)
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@ -81,16 +81,11 @@ static unsigned int mszh_decomp(const unsigned char * srcptr, int srclen, unsign
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unsigned char *destptr_bak = destptr;
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unsigned char *destptr_end = destptr + destsize;
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const unsigned char *srcptr_end = srcptr + srclen;
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unsigned char mask = 0;
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unsigned char maskbit = 0;
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unsigned char mask = *srcptr++;
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unsigned char maskbit = 0x80;
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unsigned int ofs, cnt;
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while (srcptr < srcptr_end && destptr < destptr_end) {
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if (maskbit == 0) {
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mask = *srcptr++;
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maskbit = 0x80;
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continue;
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}
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if (!(mask & maskbit)) {
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memcpy(destptr, srcptr, 4);
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destptr += 4;
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@ -105,6 +100,10 @@ static unsigned int mszh_decomp(const unsigned char * srcptr, int srclen, unsign
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destptr += cnt;
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}
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maskbit >>= 1;
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if (!maskbit) {
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mask = *srcptr++;
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maskbit = 0x80;
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}
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}
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return destptr - destptr_bak;
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