1 /*
2 * strcmp.c -- strcmp function. On at least some MIPS chips, a strcmp that is
3 * unrolled twice is faster than the 'optimized' C version in newlib.
4 *
5 * Copyright (c) 2001 Red Hat, Inc.
6 *
7 * The authors hereby grant permission to use, copy, modify, distribute,
8 * and license this software and its documentation for any purpose, provided
9 * that existing copyright notices are retained in all copies and that this
10 * notice is included verbatim in any distributions. No written agreement,
11 * license, or royalty fee is required for any of the authorized uses.
12 * Modifications to this software may be copyrighted by their authors
13 * and need not follow the licensing terms described here, provided that
14 * the new terms are clearly indicated on the first page of each file where
15 * they apply. */
16
17 #include <stddef.h>
18 #include <string.h>
19 #include <stdlib.h>
20
21 int
strcmp(const char * s1,const char * s2)22 strcmp (const char *s1, const char *s2)
23 {
24 unsigned const char *us1 = (unsigned const char *)s1;
25 unsigned const char *us2 = (unsigned const char *)s2;
26 int c1a, c1b;
27 int c2a, c2b;
28
29 /* If the pointers aren't both aligned to a 16-byte boundary, do the
30 comparison byte by byte, so that we don't get an invalid page fault if we
31 are comparing a string whose null byte is at the last byte on the last
32 valid page. */
33 if (((((long)us1) | ((long)us2)) & 1) == 0)
34 {
35 c1a = *us1;
36 for (;;)
37 {
38 c1b = *us2;
39 us1 += 2;
40 if (c1a == '\0')
41 goto ret1;
42
43 c2a = us1[-1];
44 if (c1a != c1b)
45 goto ret1;
46
47 c2b = us2[1];
48 us2 += 2;
49 if (c2a == '\0')
50 break;
51
52 c1a = *us1;
53 if (c2a != c2b)
54 break;
55 }
56
57 return c2a - c2b;
58 }
59 else
60 {
61 do
62 {
63 c1a = *us1++;
64 c1b = *us2++;
65 }
66 while (c1a != '\0' && c1a == c1b);
67 }
68
69 ret1:
70 return c1a - c1b;
71 }
72