/contrib/ntp/libntp/memmove.c

https://bitbucket.org/freebsd/freebsd-head/ · C · 140 lines · 68 code · 10 blank · 62 comment · 15 complexity · f1669d8c02e9336e60902a1725291d2d MD5 · raw file

  1. /*-
  2. * Copyright (c) 1990, 1993
  3. * The Regents of the University of California. All rights reserved.
  4. *
  5. * This code is derived from software contributed to Berkeley by
  6. * Chris Torek.
  7. *
  8. * Redistribution and use in source and binary forms, with or without
  9. * modification, are permitted provided that the following conditions
  10. * are met:
  11. * 1. Redistributions of source code must retain the above copyright
  12. * notice, this list of conditions and the following disclaimer.
  13. * 2. Redistributions in binary form must reproduce the above copyright
  14. * notice, this list of conditions and the following disclaimer in the
  15. * documentation and/or other materials provided with the distribution.
  16. * 3. All advertising materials mentioning features or use of this software
  17. * must display the following acknowledgement:
  18. * This product includes software developed by the University of
  19. * California, Berkeley and its contributors.
  20. * 4. Neither the name of the University nor the names of its contributors
  21. * may be used to endorse or promote products derived from this software
  22. * without specific prior written permission.
  23. *
  24. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34. * SUCH DAMAGE.
  35. */
  36. #if defined(LIBC_SCCS) && !defined(lint)
  37. static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
  38. #endif /* LIBC_SCCS and not lint */
  39. #ifdef HAVE_CONFIG_H
  40. # include <config.h>
  41. #endif
  42. #ifndef HAVE_MEMMOVE
  43. #ifdef HAVE_SYS_TYPES_H
  44. #include <sys/types.h>
  45. #endif
  46. #include <string.h>
  47. #include "l_stdlib.h"
  48. /*
  49. * sizeof(word) MUST BE A POWER OF TWO
  50. * SO THAT wmask BELOW IS ALL ONES
  51. */
  52. typedef int word; /* "word" used for optimal copy speed */
  53. #define wsize sizeof(word)
  54. #define wmask (wsize - 1)
  55. /*
  56. * Copy a block of memory, handling overlap.
  57. * This is the routine that actually implements
  58. * (the portable versions of) bcopy, memcpy, and memmove.
  59. */
  60. void *
  61. memmove(
  62. void *dst0,
  63. const void *src0,
  64. register size_t length
  65. )
  66. {
  67. register char *dst = dst0;
  68. register const char *src = src0;
  69. register size_t t;
  70. if (length == 0 || dst == src) /* nothing to do */
  71. goto done;
  72. /*
  73. * Macros: loop-t-times; and loop-t-times, t>0
  74. */
  75. #define TLOOP(s) if (t) TLOOP1(s)
  76. #define TLOOP1(s) do { s; } while (--t)
  77. if ((unsigned long)dst < (unsigned long)src) {
  78. /*
  79. * Copy forward.
  80. */
  81. t = (int)src; /* only need low bits */
  82. if ((t | (int)dst) & wmask) {
  83. /*
  84. * Try to align operands. This cannot be done
  85. * unless the low bits match.
  86. */
  87. if ((t ^ (int)dst) & wmask || length < wsize)
  88. t = length;
  89. else
  90. t = wsize - (t & wmask);
  91. length -= t;
  92. TLOOP1(*dst++ = *src++);
  93. }
  94. /*
  95. * Copy whole words, then mop up any trailing bytes.
  96. */
  97. t = length / wsize;
  98. TLOOP(*(word *)dst = *(const word *)src; src += wsize;
  99. dst += wsize);
  100. t = length & wmask;
  101. TLOOP(*dst++ = *src++);
  102. } else {
  103. /*
  104. * Copy backwards. Otherwise essentially the same.
  105. * Alignment works as before, except that it takes
  106. * (t&wmask) bytes to align, not wsize-(t&wmask).
  107. */
  108. src += length;
  109. dst += length;
  110. t = (int)src;
  111. if ((t | (int)dst) & wmask) {
  112. if ((t ^ (int)dst) & wmask || length <= wsize)
  113. t = length;
  114. else
  115. t &= wmask;
  116. length -= t;
  117. TLOOP1(*--dst = *--src);
  118. }
  119. t = length / wsize;
  120. TLOOP(src -= wsize; dst -= wsize;
  121. *(word *)dst = *(const word *)src);
  122. t = length & wmask;
  123. TLOOP(*--dst = *--src);
  124. }
  125. done:
  126. return (dst0);
  127. }
  128. #else
  129. int memmove_bs;
  130. #endif