/* * ======================== * ===== =============== * ====== ================ * ====== ================ * ====== ==== ==== == * ====== === == = = * ====== === = == = * = === === = == ==== * = === === = == = = * == ===== ==== == * ======================== * * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 2020 Joe * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the organization nor the * names of its contributors may be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY JOE ''AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL JOE BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * bsdsetsid: src/u_strncmp.S * 2020-11-21 14:02 * Joe * * General error handling happen here. */ .text .globl u_strncmp u_strncmp: xor %rcx, %rcx dec %rdx .u.loop: xor %r8, %r8 xor %r9, %r9 movb (%rdi, %rcx), %r8b movb (%rsi, %rcx), %r9b cmpb %r8b, %r9b jne .u.retdiff cmp %rdx, %rcx jge .u.retdiff cmpb $0x0, (%rdi, %rcx) jne .u.inc cmpb $0x0, (%rsi, %rcx) je .u.retzer .u.inc: inc %rcx jmp .u.loop .u.retdiff: xor %r8, %r8 xor %r9, %r9 movb (%rdi, %rcx), %r8b movb (%rsi, %rcx), %r9b sub %r9, %r8 xor %rax, %rax movl %r8d, %eax ret .u.retzer: xor %rax, %rax ret