/* * Copyright (c) 1983 Regents of the University of California. * All rights reserved. The Berkeley software License Agreement * specifies the terms and conditions for redistribution. */ #ifdef LIBC_SCCS .asciz "@(#)strncmp.s 5.3 (Berkeley) 3/9/86" #endif LIBC_SCCS /* * Compare at most n characters of string * s1 lexicographically to string s2. * Return: * 0 s1 == s2 * > 0 s1 > s2 * < 0 s2 < s2 * * strncmp(s1, s2, n) * char *s1, *s2; * int n; */ #include "DEFS.h" ENTRY(strncmp, 0) movl 4(ap),r1 # r1 = s1 movq 8(ap),r3 # r3 = s2; r4 = n 1: clrl r5 # calculate min bytes to next page boundry subb3 r1,$255,r5 # r5 = (bytes - 1) to end of page for s1 subb3 r3,$255,r0 # r0 = (bytes - 1) to end of page for s2 cmpb r0,r5 # r5 = min(r0, r5); bgtru 2f movb r0,r5 2: incl r5 # r5 = min bytes to next page boundry cmpl r4,r5 # r5 = min(n, r5); bgeq 3f movl r4,r5 3: cmpc3 r5,(r1),(r3) # compare strings bneq 4f subl2 r5,r4 # check for end of comparison beql 5f subl2 r5,r1 # check if found null yet locc $0,r5,(r1) beql 1b # not yet done, continue checking subl2 r0,r3 mnegb (r3),r0 # r0 = '\0' - *s2 cvtbl r0,r0 ret 4: subl2 r0,r5 # check for null in matching string subl2 r5,r1 locc $0,r5,(r1) bneq 5f subb3 (r3),(r1),r0 # r0 = *s1 - *s2 cvtbl r0,r0 ret 5: clrl r0 # both the same to null ret