1/*
2 * Copyright (c) 2000-2001 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28;
29#include <ppc/asm.h>
30#include <ppc/proc_reg.h>
31;
32; int	bcmp(const void *LHS, const void *RHS, size_t len);
33;
34; Because bcmp returns zero if equal and nonzero otherwise, it is slightly
35; faster than memcmp, which returns the difference between the first different
36; bytes.
37; 	r3 - LHS
38; 	r4 - RHS
39; 	r5 - len
40
41	.align	5
42	.globl	EXT(bcmp)
43LEXT(bcmp)
44
45	cmpwi	cr1,r5,6		; six chars long?
46	mr	r6,r3			; copy LHS ptr so we can use r3 as result
47	mr.	r3,r5			; test length and move to r3
48	bgt	cr1,Llong		; more than 6 chars long
49	blt	cr1,Lshort		; less than 6
50
51	; most common operand length is 6 chars (enet addrs)
52
53	lwz	r8,0(r6)		; first 4 bytes of LHS
54	lwz	r7,0(r4)		; and RHS
55	lhz	r9,4(r6)		; next 2 of LHS
56	sub.	r3,r8,r7		; compare first 4
57	bnelr				; first 4 differed (r3!=0)
58	lhz	r10,4(r4)		; next 2 of RHS
59	sub	r3,r9,r10		; compare last 2
60	blr				; done, result in r3
61
62	; handle long strings
63Llong:
64	srwi	r0,r5,2			; r0 = word len
65	mtctr	r0			; set up for loop
66Llongloop:
67	lwz	r8,0(r6)		; next 4 bytes from LHS
68	addi	r6,r6,4
69	lwz	r7,0(r4)		; next 4 from RHS
70	addi	r4,r4,4
71	sub.	r3,r8,r7		; compare next 4 bytes
72	bdnzt+	eq,Llongloop		; loop if ctr!=0 and cr0_eq
73	bnelr				; done if not equal (r3!=0)
74
75	andi.	r5,r5,3			; more to go?
76
77	; compare short strings (0-5 bytes long)
78	;  	r5 = length remaining
79	;	cr0= set on length
80	;	r3 = zero if length is zero
81Lshort:
82	beqlr				; done (r3=0)
83	mtctr	r5
84Lshortloop:
85	lbz	r8,0(r6)		; get next byte from LHS
86	addi	r6,r6,1
87	lbz	r7,0(r4)		; and next byte from RHS
88	addi	r4,r4,1
89	sub.	r3,r8,r7		; compare
90	bdnzt+	eq,Lshortloop		; loop if ctr!=0 and cr0_eq
91	blr				; done, r3 set correctly by the subtract
92
93