55 lines
1.4 KiB
C
55 lines
1.4 KiB
C
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#include <common.h>
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/* Nonzero if either X or Y is not aligned on a "long" boundary. */
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#define UNALIGNED(X, Y) \
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(((long)X & (sizeof(long) - 1)) | ((long)Y & (sizeof(long) - 1)))
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/* How many bytes are copied each iteration of the 4X unrolled loop. */
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#define BIGBLOCKSIZE (sizeof(long) << 2)
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/* How many bytes are copied each iteration of the word copy loop. */
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#define LITTLEBLOCKSIZE (sizeof(long))
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/* Threshhold for punting to the byte copier. */
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#define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE)
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void * memcpy( void *dst0, const void* src0, size_t len0)
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{
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char *dst = dst0;
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const char *src = src0;
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long *aligned_dst;
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long *aligned_src;
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/* If the size is small, or either SRC or DST is unaligned,
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then punt into the byte copy loop. This should be rare. */
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if (!TOO_SMALL(len0) && !UNALIGNED(src, dst)) {
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aligned_dst = (long *)dst;
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aligned_src = (long *)src;
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/* Copy 4X long words at a time if possible. */
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while (len0 >= BIGBLOCKSIZE) {
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*aligned_dst++ = *aligned_src++;
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*aligned_dst++ = *aligned_src++;
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*aligned_dst++ = *aligned_src++;
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*aligned_dst++ = *aligned_src++;
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len0 -= BIGBLOCKSIZE;
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}
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/* Copy one long word at a time if possible. */
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while (len0 >= LITTLEBLOCKSIZE) {
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*aligned_dst++ = *aligned_src++;
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len0 -= LITTLEBLOCKSIZE;
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}
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/* Pick up any residual with a byte copier. */
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dst = (char *)aligned_dst;
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src = (char *)aligned_src;
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}
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while (len0--)
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*dst++ = *src++;
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return dst0;
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}
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