memmove.c 2.2 KB

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  1. /*
  2. * This string-include defines all string functions as inline
  3. * functions. Use gcc. It also assumes ds=es=data space, this should be
  4. * normal. Most of the string-functions are rather heavily hand-optimized,
  5. * see especially strtok,strstr,str[c]spn. They should work, but are not
  6. * very easy to understand. Everything is done entirely within the register
  7. * set, making the functions fast and clean. String instructions have been
  8. * used through-out, making for "slightly" unclear code :-)
  9. *
  10. * NO Copyright (C) 1991, 1992 Linus Torvalds,
  11. * consider these trivial functions to be PD.
  12. */
  13. /*
  14. * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
  15. *
  16. * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
  17. */
  18. /*
  19. * Modified for uClibc by Erik Andersen <andersen@codepoet.org>
  20. * These make no attempt to use nifty things like mmx/3dnow/etc.
  21. * These are not inline, and will therefore not be as fast as
  22. * modifying the headers to use inlines (and cannot therefore
  23. * do tricky things when dealing with const memory). But they
  24. * should (I hope!) be faster than their generic equivalents....
  25. *
  26. * More importantly, these should provide a good example for
  27. * others to follow when adding arch specific optimizations.
  28. * -Erik
  29. */
  30. #include <string.h>
  31. #undef memmove
  32. //#define memmove TESTING
  33. void *memmove(void *dest, const void *src, size_t n)
  34. {
  35. int eax, ecx, esi, edi;
  36. __asm__ __volatile__(
  37. " movl %%eax, %%edi\n"
  38. " cmpl %%esi, %%eax\n"
  39. " je 2f\n" /* (optional) src == dest -> NOP */
  40. " jb 1f\n" /* src > dest -> simple copy */
  41. " leal -1(%%esi,%%ecx), %%esi\n"
  42. " leal -1(%%eax,%%ecx), %%edi\n"
  43. " std\n"
  44. "1: rep; movsb\n"
  45. " cld\n"
  46. "2:\n"
  47. : "=&c" (ecx), "=&S" (esi), "=&a" (eax), "=&D" (edi)
  48. : "0" (n), "1" (src), "2" (dest)
  49. : "memory"
  50. );
  51. return (void*)eax;
  52. }
  53. #ifndef memmove
  54. libc_hidden_def(memmove)
  55. #else
  56. /* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os memmove.c -o memmove
  57. * and run ./memmove
  58. */
  59. int main()
  60. {
  61. static char str[] = "abcdef.123";
  62. memmove(str + 1, str, 5);
  63. printf(strcmp(str, "aabcde.123") == 0 ? "ok\n" : "BAD!\n");
  64. memmove(str, str + 1, 5);
  65. printf(strcmp(str, "abcdee.123") == 0 ? "ok\n" : "BAD!\n");
  66. }
  67. #endif