projects / apple / xnu.git / blame
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|---|---|---|
| 0b4e3aa0 A |
1 | /* |
| 2 | * Copyright (c) 2000-2001 Apple Computer, Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| d7e50217 | 6 | * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. |
| 0b4e3aa0 | 7 | * |
| d7e50217 A |
8 | * This file contains Original Code and/or Modifications of Original Code |
| 9 | * as defined in and that are subject to the Apple Public Source License | |
| 10 | * Version 2.0 (the 'License'). You may not use this file except in | |
| 11 | * compliance with the License. Please obtain a copy of the License at | |
| 12 | * http://www.opensource.apple.com/apsl/ and read it before using this | |
| 13 | * file. | |
| 14 | * | |
| 15 | * The Original Code and all software distributed under the License are | |
| 16 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
| 0b4e3aa0 A |
17 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 18 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| d7e50217 A |
19 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
| 20 | * Please see the License for the specific language governing rights and | |
| 21 | * limitations under the License. | |
| 0b4e3aa0 A |
22 | * |
| 23 | * @APPLE_LICENSE_HEADER_END@ | |
| 24 | */ | |
| 25 | ; | |
| 26 | #include <ppc/asm.h> | |
| 27 | #include <ppc/proc_reg.h> | |
| 28 | ; | |
| 29 | ; int bcmp(const void *LHS, const void *RHS, size_t len); | |
| 30 | ; | |
| 31 | ; Because bcmp returns zero if equal and nonzero otherwise, it is slightly | |
| 32 | ; faster than memcmp, which returns the difference between the first different | |
| 33 | ; bytes. | |
| 34 | ; r3 - LHS | |
| 35 | ; r4 - RHS | |
| 36 | ; r5 - len | |
| 37 | ||
| 38 | .align 5 | |
| 39 | .globl EXT(bcmp) | |
| 40 | LEXT(bcmp) | |
| 41 | ||
| 42 | cmpwi cr1,r5,6 ; six chars long? | |
| 43 | mr r6,r3 ; copy LHS ptr so we can use r3 as result | |
| 44 | mr. r3,r5 ; test length and move to r3 | |
| 45 | bgt cr1,Llong ; more than 6 chars long | |
| 46 | blt cr1,Lshort ; less than 6 | |
| 47 | ||
| 48 | ; most common operand length is 6 chars (enet addrs) | |
| 49 | ||
| 50 | lwz r8,0(r6) ; first 4 bytes of LHS | |
| 51 | lwz r7,0(r4) ; and RHS | |
| 52 | lhz r9,4(r6) ; next 2 of LHS | |
| 53 | sub. r3,r8,r7 ; compare first 4 | |
| 54 | bnelr ; first 4 differed (r3!=0) | |
| 55 | lhz r10,4(r4) ; next 2 of RHS | |
| 56 | sub r3,r9,r10 ; compare last 2 | |
| 57 | blr ; done, result in r3 | |
| 58 | ||
| 59 | ; handle long strings | |
| 60 | Llong: | |
| 61 | srwi r0,r5,2 ; r0 = word len | |
| 62 | mtctr r0 ; set up for loop | |
| 63 | Llongloop: | |
| 64 | lwz r8,0(r6) ; next 4 bytes from LHS | |
| 65 | addi r6,r6,4 | |
| 66 | lwz r7,0(r4) ; next 4 from RHS | |
| 67 | addi r4,r4,4 | |
| 68 | sub. r3,r8,r7 ; compare next 4 bytes | |
| 69 | bdnzt+ eq,Llongloop ; loop if ctr!=0 and cr0_eq | |
| 70 | bnelr ; done if not equal (r3!=0) | |
| 71 | ||
| 72 | andi. r5,r5,3 ; more to go? | |
| 73 | ||
| 74 | ; compare short strings (0-5 bytes long) | |
| 75 | ; r5 = length remaining | |
| 76 | ; cr0= set on length | |
| 77 | ; r3 = zero if length is zero | |
| 78 | Lshort: | |
| 79 | beqlr ; done (r3=0) | |
| 80 | mtctr r5 | |
| 81 | Lshortloop: | |
| 82 | lbz r8,0(r6) ; get next byte from LHS | |
| 83 | addi r6,r6,1 | |
| 84 | lbz r7,0(r4) ; and next byte from RHS | |
| 85 | addi r4,r4,1 | |
| 86 | sub. r3,r8,r7 ; compare | |
| 87 | bdnzt+ eq,Lshortloop ; loop if ctr!=0 and cr0_eq | |
| 88 | blr ; done, r3 set correctly by the subtract | |
| 89 |