projects / dragonfly.git / blame
| Commit | Line | Data |
|---|---|---|
| d7f50089 | 1 | /* |
| c8fe38ae | 2 | * Copyright (c) 2003,2004,2008 The DragonFly Project. All rights reserved. |
| d7f50089 YY |
3 | * |
| 4 | * This code is derived from software contributed to The DragonFly Project | |
| 5 | * by Matthew Dillon <dillon@backplane.com> | |
| 6 | * | |
| 7 | * Redistribution and use in source and binary forms, with or without | |
| 8 | * modification, are permitted provided that the following conditions | |
| 9 | * are met: | |
| 10 | * | |
| 11 | * 1. Redistributions of source code must retain the above copyright | |
| 12 | * notice, this list of conditions and the following disclaimer. | |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright | |
| 14 | * notice, this list of conditions and the following disclaimer in | |
| 15 | * the documentation and/or other materials provided with the | |
| 16 | * distribution. | |
| 17 | * 3. Neither the name of The DragonFly Project nor the names of its | |
| 18 | * contributors may be used to endorse or promote products derived | |
| 19 | * from this software without specific, prior written permission. | |
| 20 | * | |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 23 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| 24 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| 25 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 26 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
| 27 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
| 28 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED | |
| 29 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | |
| 30 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
| 31 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 32 | * SUCH DAMAGE. | |
| d7f50089 YY |
33 | */ |
| 34 | ||
| 35 | #include <machine/asmacros.h> /* miscellaneous asm macros */ | |
| 36 | ||
| 37 | #include "assym.s" | |
| 38 | ||
| 39 | .text | |
| 40 | ||
| 41 | /* | |
| 42 | * asm_ones32(32bitalignedbuffer, numberof32bitwords) | |
| 43 | * | |
| 44 | * Returns the 32 bit one complement partial checksum. This is | |
| 45 | * basically a 1's complement checksum without the inversion (~) | |
| 46 | * at the end. A 32 bit value is returned. If the caller is | |
| 47 | * calculating a 16 bit 1's complement checksum the caller must | |
| 48 | * collapse the 32 bit return value via: | |
| 49 | * | |
| 50 | * result = (result >> 16) + (result & 0xFFFF) | |
| 51 | * if (result > 0xFFFF) | |
| 52 | * result -= 0xFFFF; <<< same as (result + 1) & 0xFFFF | |
| 53 | * within the range of result. | |
| 54 | * Note that worst case 0xFFFFFFFF + 0xFFFFFFFF = 0xFFFFFFFE + CARRY, | |
| 55 | * so no double-carry ever occurs. | |
| 56 | */ | |
| 57 | .p2align 4 | |
| 58 | ENTRY(asm_ones32) | |
| c8fe38ae MD |
59 | movq %rdi,%rdx /* %rdx = buffer pointer */ |
| 60 | movl %esi,%ecx /* %ecx = counter */ | |
| 61 | xorl %eax,%eax /* %eax = checksum */ | |
| d7f50089 YY |
62 | cmpl $5,%ecx |
| 63 | jl 2f | |
| 64 | 1: | |
| 65 | subl $5,%ecx | |
| c8fe38ae MD |
66 | addl (%rdx),%eax |
| 67 | adcl 4(%rdx),%eax | |
| 68 | adcl 8(%rdx),%eax | |
| 69 | adcl 12(%rdx),%eax | |
| 70 | adcl 16(%rdx),%eax | |
| d7f50089 | 71 | adcl $0,%eax |
| c8fe38ae | 72 | addq $20,%rdx |
| d7f50089 YY |
73 | cmpl $5,%ecx |
| 74 | jge 1b | |
| 75 | 2: | |
| 76 | testl %ecx,%ecx | |
| 77 | je 4f | |
| 78 | 3: | |
| c8fe38ae | 79 | addl (%rdx),%eax |
| d7f50089 | 80 | adcl $0,%eax |
| c8fe38ae | 81 | addq $4,%rdx |
| d7f50089 YY |
82 | decl %ecx |
| 83 | jnz 3b | |
| 84 | 4: | |
| 85 | ret |