/* * strcmp.c -- strcmp function. On at least some MIPS chips, a strcmp that is * unrolled twice is faster than the 'optimized' C version in newlib. * * Copyright (c) 2001 Red Hat, Inc. * * The authors hereby grant permission to use, copy, modify, distribute, * and license this software and its documentation for any purpose, provided * that existing copyright notices are retained in all copies and that this * notice is included verbatim in any distributions. No written agreement, * license, or royalty fee is required for any of the authorized uses. * Modifications to this software may be copyrighted by their authors * and need not follow the licensing terms described here, provided that * the new terms are clearly indicated on the first page of each file where * they apply. */ #include #include #include int strcmp (const char *s1, const char *s2) { unsigned const char *us1 = (unsigned const char *)s1; unsigned const char *us2 = (unsigned const char *)s2; int c1a, c1b; int c2a, c2b; /* If the pointers aren't both aligned to a 16-byte boundary, do the comparison byte by byte, so that we don't get an invalid page fault if we are comparing a string whose null byte is at the last byte on the last valid page. */ if (((((long)us1) | ((long)us2)) & 1) == 0) { c1a = *us1; for (;;) { c1b = *us2; us1 += 2; if (c1a == '\0') goto ret1; c2a = us1[-1]; if (c1a != c1b) goto ret1; c2b = us2[1]; us2 += 2; if (c2a == '\0') break; c1a = *us1; if (c2a != c2b) break; } return c2a - c2b; } else { do { c1a = *us1++; c1b = *us2++; } while (c1a != '\0' && c1a == c1b); } ret1: return c1a - c1b; }
