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#include <windows.h>
#include <stdio.h>
#ifdef _WIN64
int have_sse2 = 0;
void fast_memcpy_aligned(void *dest, const void *src, size_t len);
#else
static _inline void fast_memcpy_aligned(void *dest, const void *src, size_t len)
{
_asm
{
mov ecx, len
mov esi, src
mov edi, dest
cmp ecx, 128
jb try_to_copy64
prefetchnta [esi]
copy_128:
prefetchnta [esi + 64]
movdqa xmm0, [esi]
movdqa xmm1, [esi + 16]
movdqa xmm2, [esi + 32]
movdqa xmm3, [esi + 48]
prefetchnta [esi + 128]
movntdq [edi], xmm0
movntdq [edi + 16], xmm1
movntdq [edi + 32], xmm2
movntdq [edi + 48], xmm3
movdqa xmm0, [esi + 64]
movdqa xmm1, [esi + 80]
movdqa xmm2, [esi + 96]
movdqa xmm3, [esi + 112]
movntdq [edi + 64], xmm0
movntdq [edi + 80], xmm1
movntdq [edi + 96], xmm2
movntdq [edi + 112], xmm3
add edi, 128
add esi, 128
sub ecx, 128
cmp ecx, 128
jae copy_128
try_to_copy64:
cmp ecx, 64
jb try_to_copy32
movdqa xmm0, [esi]
movdqa xmm1, [esi + 16]
movdqa xmm2, [esi + 32]
movdqa xmm3, [esi + 48]
movntdq [edi], xmm0
movntdq [edi + 16], xmm1
movntdq [edi + 32], xmm2
movntdq [edi + 48], xmm3
add edi, 64
add esi, 64
sub ecx, 64
prefetchnta [esi]
try_to_copy32:
cmp ecx, 32
jb try_to_copy16
movdqa xmm0, [esi]
movdqa xmm1, [esi + 16]
movntdq [edi], xmm0
movntdq [edi + 16], xmm1
add edi, 32
add esi, 32
sub ecx, 32
try_to_copy16:
cmp ecx, 16
jb try_to_copy4
movdqa xmm0, [esi]
movntdq [edi], xmm0
add edi, 16
add esi, 16
sub ecx, 16
try_to_copy4:
cmp ecx, 4
jb try_to_copy_1
movsd
sub ecx, 4
jmp try_to_copy4
try_to_copy_1:
rep movsb
sfence
}
}
#endif
typedef unsigned long long uint64_t;
uint64_t time_usecs(void)
{
SYSTEMTIME systime;
GetSystemTime(&systime);
return systime.wMilliseconds * 1000 + systime.wSecond * 1e6 + systime.wMinute * 60e6 + systime.wHour * 3600e6;
}
int main(void)
{
int i;
unsigned char *src_unaligned;
unsigned char *dest_unaligned;
uint64_t start, total1, total2;
unsigned char *src = NULL;
unsigned char *dest = NULL;
size_t size = 1024;
size_t iter = 1024 * 1024;
printf("fast_memcpy compared to memcpy (< 1.0 means memcpy is better)\n");
for (size = 1024; size < 1024*1024*2; size *= 2, iter /= 2) {
src_unaligned = malloc(size + 15);
dest_unaligned = malloc(size + 15);
src = (unsigned char *)((size_t)(src_unaligned + 15) & ~0xf);
dest = (unsigned char *)((size_t)(dest_unaligned + 15) & ~0xf);
start = time_usecs();
for (i = 0 ; i < iter ; ++i)
memcpy(dest, src, size);
total1 = time_usecs() - start;
start = time_usecs();
for (i = 0 ; i < iter ; ++i)
fast_memcpy_aligned(dest, src, size);
total2 = time_usecs() - start;
printf("%d: %f (%d, ", size, ((float)total1) / total2, total1);
printf("%d)\n", total2);
free(src_unaligned);
free(dest_unaligned);
}
return 0;
}
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