15
15
* Nonstandard instructions used:
19
void *ac_memcpy_mmx(void *dest, const void *src, size_t bytes)
22
#PENTIUM_LINE_SIZE = 32 # PMMX/PII cache line size \n\
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#PENTIUM_CACHE_SIZE = 8192 # PMMX/PII total cache size \n\
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# Use only half because writes may touch the cache too (PII) \n\
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#PENTIUM_CACHE_BLOCK = (PENTIUM_CACHE_SIZE/2 - PENTIUM_LINE_SIZE) \n\
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push %%ebx # Save PIC register \n\
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push %%edi # Save destination for return value \n\
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cld # MOVS* should ascend \n\
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mov $64, %%ebx # Constant \n\
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jb mmx.memcpy_last # Just use movs if <64 bytes \n\
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# First align destination address to a multiple of 8 bytes \n\
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mov $8, %%eax # EAX <- (8-dest) & 7 \n\
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and $0b111, %%eax # ... which is the number of bytes to copy\n\
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lea 0f, %%edx # Use a computed jump--faster than a loop\n\
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jmp *%%edx # Execute 0-7 MOVSB's \n\
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0: sub %%eax, %%ecx # Update count \n\
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# Now copy data in blocks \n\
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0: mov %%ecx, %%edx # EDX <- ECX >> 6 (cache lines to copy) \n\
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jz mmx.memcpy_last # <64 bytes left? Skip to end \n\
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cmp 63, %%edx # Solaris x86 fix \n\
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jb 1f # Limit size of block \n\
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mov 63, %%edx # Solaris x86 fix \n\
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1: mov %%edx, %%eax # EAX <- EDX << 6 (bytes to copy) \n\
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sub %%eax, %%ecx # Update remaining count \n\
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add %%eax, %%esi # Point to end of region to be block-copied\n\
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2: test %%eax, -32(%%esi) # Touch each cache line in reverse order\n\
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test %%eax, -64(%%esi) \n\
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sub %%ebx, %%esi # Update pointer \n\
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sub %%ebx, %%eax # And loop \n\
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# Note that ESI now points to the beginning of the block \n\
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3: movq (%%esi), %%mm0 # Do the actual copy, 64 bytes at a time\n\
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movq 8(%%esi), %%mm1 \n\
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movq 16(%%esi), %%mm2 \n\
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movq 24(%%esi), %%mm3 \n\
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movq 32(%%esi), %%mm4 \n\
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movq 40(%%esi), %%mm5 \n\
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movq 48(%%esi), %%mm6 \n\
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movq 56(%%esi), %%mm7 \n\
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movq %%mm0, (%%edi) \n\
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movq %%mm1, 8(%%edi) \n\
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movq %%mm2, 16(%%edi) \n\
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movq %%mm3, 24(%%edi) \n\
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movq %%mm4, 32(%%edi) \n\
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movq %%mm5, 40(%%edi) \n\
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movq %%mm6, 48(%%edi) \n\
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movq %%mm7, 56(%%edi) \n\
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add %%ebx, %%esi # Update pointers \n\
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dec %%edx # And loop \n\
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# Copy last <64 bytes, using the computed jump trick \n\
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mov %%ecx, %%eax # EAX <- ECX>>2 \n\
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jmp *%%edx # Execute 0-15 MOVSD's \n\
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0: and $0b11, %%ecx # ECX <- ECX & 3 \n\
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jmp *%%edx # Execute 0-3 MOVSB's \n\
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emms # Clean up MMX state \n\
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pop %%edi # Restore destination (return value) \n\
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pop %%ebx # Restore PIC register \n\
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: "D" (dest), "S" (src), "c" (bytes)
19
132
void *ac_memcpy_mmx(void *dest, const void *src, size_t bytes)
added
removed
src/tcmemcpy.c
