1/* 2 * Copyright (c) 2003,2004,2008 The DragonFly Project. All rights reserved. 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. 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 58ENTRY(asm_ones32) 59 movq %rdi,%rdx /* %rdx = buffer pointer */ 60 movl %esi,%ecx /* %ecx = counter */ 61 xorl %eax,%eax /* %eax = checksum */ 62 cmpl $5,%ecx 63 jl 2f 641: 65 subl $5,%ecx 66 addl (%rdx),%eax 67 adcl 4(%rdx),%eax 68 adcl 8(%rdx),%eax 69 adcl 12(%rdx),%eax 70 adcl 16(%rdx),%eax 71 adcl $0,%eax 72 addq $20,%rdx 73 cmpl $5,%ecx 74 jge 1b 752: 76 testl %ecx,%ecx 77 je 4f 783: 79 addl (%rdx),%eax 80 adcl $0,%eax 81 addq $4,%rdx 82 decl %ecx 83 jnz 3b 844: 85 ret 86END(asm_ones32) 87