/* * Copyright (c) 1993,94 Winning Strategies, Inc. * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Winning Strategies, Inc. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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. */ #include <machine/asm.h> /* * strncmp(s1, s2, n) * return an integer greater than, equal to, or less than 0, * according as the first n characters of string s1 is greater * than, equal to, or less than the string s2. * * %eax - pointer to s1 * %ecx - pointer to s2 * %edx - length * * Written by: * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. */ /* * I've unrolled the loop eight times: large enough to make a * significant difference, and small enough not to totally trash the * cache. * * TODO: change all the jz's back to je for consistency. */ ENTRY(strncmp) pushl %ebx movl 8(%esp),%eax movl 12(%esp),%ecx movl 16(%esp),%edx testl %edx,%edx jmp L2 /* Jump into the loop! */ .align 2,0x90 L1: incl %eax incl %ecx decl %edx L2: jz L4 /* strings are equal */ movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 /* * XXX it might be best to move the next 4 instructions to the end of the * unrolled part of the loop. The unrolled part would then be * movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3 * or maybe better * movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0 * for n = 0, 1, ..., 8. The end of the loop would be * L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx * where residual counts of 0 to 7 are handled at Lx. However, this would * be slower for short strings. Cache effects are probably not so * important because we are only handling a byte at a time. */ incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) jne L3 incl %eax incl %ecx decl %edx jz L4 movb (%eax),%bl testb %bl,%bl jz L3 cmpb %bl,(%ecx) je L1 .align 2,0x90 L3: movzbl (%eax),%eax /* unsigned comparison */ movzbl (%ecx),%ecx subl %ecx,%eax popl %ebx ret .align 2,0x90 L4: xorl %eax,%eax popl %ebx ret END(strncmp) .section .note.GNU-stack,"",%progbits
