memcpy.c (1288B)
1 /* 2 ** Copyright 2001, Travis Geiselbrecht. All rights reserved. 3 ** Distributed under the terms of the NewOS License. 4 */ 5 /* 6 * Copyright (c) 2008 Travis Geiselbrecht 7 * 8 * Use of this source code is governed by a MIT-style 9 * license that can be found in the LICENSE file or at 10 * https://opensource.org/licenses/MIT 11 */ 12 #include <string.h> 13 #include <stdint.h> 14 15 16 #if !_ASM_MEMCPY 17 18 typedef long word; 19 20 #define lsize sizeof(word) 21 #define lmask (lsize - 1) 22 23 void *memcpy(void *dest, const void *src, size_t count) { 24 char *d = (char *)dest; 25 const char *s = (const char *)src; 26 int len; 27 28 if (count == 0 || dest == src) 29 return dest; 30 31 if (((long)d | (long)s) & lmask) { 32 // src and/or dest do not align on word boundary 33 if ((((long)d ^ (long)s) & lmask) || (count < lsize)) 34 len = count; // copy the rest of the buffer with the byte mover 35 else 36 len = lsize - ((long)d & lmask); // move the ptrs up to a word boundary 37 38 count -= len; 39 for (; len > 0; len--) 40 *d++ = *s++; 41 } 42 for (len = count / lsize; len > 0; len--) { 43 *(word *)d = *(word *)s; 44 d += lsize; 45 s += lsize; 46 } 47 for (len = count & lmask; len > 0; len--) 48 *d++ = *s++; 49 50 return dest; 51 } 52 53 #endif