mirror of https://github.com/mpv-player/mpv
92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
/*
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This part of code was taken by from Linux-2.4.3 and slightly modified
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for MMX2 instruction set. I have done it since linux uses page aligned
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blocks but mplayer uses weakly ordered data and original sources can not
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speedup their. Only using prefetchnta and movntq together have effect!
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If you have questions please contact with me: Nick Kurshev: nickols_k@mail.ru.
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*/
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#ifdef HAVE_MMX2
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/* for small memory blocks (<256 bytes) this version is faster */
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#define small_memcpy(to,from,n)\
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{\
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__asm__ __volatile__(\
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"rep ; movsb\n"\
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::"D" (to), "S" (from),"c" (n)\
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: "memory");\
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}
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inline static void * fast_memcpy(void * to, const void * from, unsigned len)
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{
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void *p;
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int i;
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if(len >= 0x200) /* 512-byte blocks */
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{
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p = to;
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i = len >> 6; /* len/64 */
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len&=63;
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__asm__ __volatile__ (
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"prefetchnta (%0)\n"
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"prefetchnta 64(%0)\n"
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"prefetchnta 128(%0)\n"
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"prefetchnta 192(%0)\n"
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"prefetchnta 256(%0)\n"
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: : "r" (from) );
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/*
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This algorithm is top effective when the code consequently
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reads and writes blocks which have size of cache line.
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Size of cache line is processor-dependent.
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It will, however, be a minimum of 32 bytes on any processors.
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It would be better to have a number of instructions which
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perform reading and writing to be multiple to a number of
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processor's decoders, but it's not always possible.
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*/
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for(; i>0; i--)
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{
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__asm__ __volatile__ (
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"prefetchnta 320(%0)\n"
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#ifdef HAVE_SSE /* Only P3 (may be Cyrix3) */
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"movups (%0), %%xmm0\n"
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"movups 16(%0), %%xmm1\n"
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"movntps %%xmm0, (%1)\n"
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"movntps %%xmm1, 16(%1)\n"
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"movups 32(%0), %%xmm0\n"
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"movups 48(%0), %%xmm1\n"
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"movntps %%xmm0, 32(%1)\n"
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"movntps %%xmm1, 48(%1)\n"
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#else /* Only K7 (may be other) */
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"movq (%0), %%mm0\n"
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"movq 8(%0), %%mm1\n"
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"movq 16(%0), %%mm2\n"
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"movq 24(%0), %%mm3\n"
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"movntq %%mm0, (%1)\n"
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"movntq %%mm1, 8(%1)\n"
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"movntq %%mm2, 16(%1)\n"
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"movntq %%mm3, 24(%1)\n"
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"movq 32(%0), %%mm0\n"
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"movq 40(%0), %%mm1\n"
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"movq 48(%0), %%mm2\n"
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"movq 56(%0), %%mm3\n"
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"movntq %%mm0, 32(%1)\n"
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"movntq %%mm1, 40(%1)\n"
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"movntq %%mm2, 48(%1)\n"
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"movntq %%mm3, 56(%1)\n"
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#endif
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:: "r" (from), "r" (to) : "memory");
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from+=64;
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to+=64;
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}
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__asm__ __volatile__ ("emms":::"memory");
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}
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/*
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* Now do the tail of the block
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*/
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small_memcpy(to, from, len);
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return p;
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}
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#define memcpy(a,b,c) fast_memcpy(a,b,c)
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#endif
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