Add alternative memcpy implementation
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core/klibc.c
62
core/klibc.c
@ -16,14 +16,66 @@ int memcmp(const void *aptr, const void *bptr, size_t size)
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return 0;
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return 0;
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}
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}
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void *memcpy(void *dst, const void *src, size_t n)
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// Inspirated by https://interrupt.memfault.com/blog/memcpy-newlib-nano
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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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{
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char *dstChar = dst;
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#if 0
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const char *srcChar = src;
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char *dstChar = dst0;
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for (size_t i = 0; i < n; i++) {
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const char *srcChar = src0;
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for (size_t i = 0; i < len0; i++) {
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*(dstChar++) = *(srcChar++);
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*(dstChar++) = *(srcChar++);
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}
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}
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return dst;
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return dst0;
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#else
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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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const 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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#endif
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}
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}
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void *memset(void *src, int c, size_t n)
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void *memset(void *src, int c, size_t n)
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