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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [string/] [memcmp.c] - Rev 307
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/* FUNCTION <<memcmp>>---compare two memory areas INDEX memcmp ANSI_SYNOPSIS #include <string.h> int memcmp(const void *<[s1]>, const void *<[s2]>, size_t <[n]>); TRAD_SYNOPSIS #include <string.h> int memcmp(<[s1]>, <[s2]>, <[n]>) void *<[s1]>; void *<[s2]>; size_t <[n]>; DESCRIPTION This function compares not more than <[n]> characters of the object pointed to by <[s1]> with the object pointed to by <[s2]>. RETURNS The function returns an integer greater than, equal to or less than zero according to whether the object pointed to by <[s1]> is greater than, equal to or less than the object pointed to by <[s2]>. PORTABILITY <<memcmp>> is ANSI C. <<memcmp>> requires no supporting OS subroutines. QUICKREF memcmp ansi pure */ #include <string.h> /* Nonzero if either X or Y is not aligned on a "long" boundary. */ #define UNALIGNED(X, Y) \ (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) /* How many bytes are copied each iteration of the word copy loop. */ #define LBLOCKSIZE (sizeof (long)) /* Threshhold for punting to the byte copier. */ #define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) int _DEFUN (memcmp, (m1, m2, n), _CONST _PTR m1 _AND _CONST _PTR m2 _AND size_t n) { #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) unsigned char *s1 = (unsigned char *) m1; unsigned char *s2 = (unsigned char *) m2; while (n--) { if (*s1 != *s2) { return *s1 - *s2; } s1++; s2++; } return 0; #else unsigned char *s1 = (unsigned char *) m1; unsigned char *s2 = (unsigned char *) m2; unsigned long *a1; unsigned long *a2; /* If the size is too small, or either pointer is unaligned, then we punt to the byte compare loop. Hopefully this will not turn up in inner loops. */ if (!TOO_SMALL(n) && !UNALIGNED(s1,s2)) { /* Otherwise, load and compare the blocks of memory one word at a time. */ a1 = (unsigned long*) s1; a2 = (unsigned long*) s2; while (n >= LBLOCKSIZE) { if (*a1 != *a2) break; a1++; a2++; n -= LBLOCKSIZE; } /* check m mod LBLOCKSIZE remaining characters */ s1 = (unsigned char*)a1; s2 = (unsigned char*)a2; } while (n--) { if (*s1 != *s2) return *s1 - *s2; s1++; s2++; } return 0; #endif /* not PREFER_SIZE_OVER_SPEED */ }
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