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 * the Systems Programming Group of the University of Utah Computer 7 * Science Department. 8 * 9 * %sccs.include.redist.c% 10 */ 11 12#if defined(LIBC_SCCS) && !defined(lint) 13 .asciz "@(#)bcmp.s 8.1 (Berkeley) 06/04/93" 14#endif /* LIBC_SCCS and not lint */ 15 16/* bcmp(s1, s2, n) */ 17 18#include "DEFS.h" 19 20/* 21 * This is probably not the best we can do, but it is still 2-10 times 22 * faster than the C version in the portable gen directory. 23 * 24 * Things that might help: 25 * - longword align when possible (only on the 68020) 26 * - use nested DBcc instructions or use one and limit size to 64K 27 */ 28ENTRY(bcmp) 29 movl sp@(4),a0 /* string 1 */ 30 movl sp@(8),a1 /* string 2 */ 31 movl sp@(12),d0 /* length */ 32 jeq bcdone /* if zero, nothing to do */ 33 movl a0,d1 34 btst #0,d1 /* string 1 address odd? */ 35 jeq bceven /* no, skip alignment */ 36 cmpmb a0@+,a1@+ /* yes, compare a byte */ 37 jne bcnoteq /* not equal, return non-zero */ 38 subql #1,d0 /* adjust count */ 39 jeq bcdone /* count 0, reutrn zero */ 40bceven: 41 movl a1,d1 42 btst #0,d1 /* string 2 address odd? */ 43 jne bcbloop /* yes, no hope for alignment, compare bytes */ 44 movl d0,d1 /* no, both even */ 45 lsrl #2,d1 /* convert count to longword count */ 46 jeq bcbloop /* count 0, skip longword loop */ 47bclloop: 48 cmpml a0@+,a1@+ /* compare a longword */ 49 jne bcnoteq /* not equal, return non-zero */ 50 subql #1,d1 /* adjust count */ 51 jne bclloop /* still more, keep comparing */ 52 andl #3,d0 /* what remains */ 53 jeq bcdone /* nothing, all done */ 54bcbloop: 55 cmpmb a0@+,a1@+ /* compare a byte */ 56 jne bcnoteq /* not equal, return non-zero */ 57 subql #1,d0 /* adjust count */ 58 jne bcbloop /* still more, keep going */ 59 rts 60bcnoteq: 61 moveq #1,d0 62bcdone: 63 rts 64