From 3f02f778cdbec7d95e0a9d6f9368ce9cda0a6d03 Mon Sep 17 00:00:00 2001 From: Greg McGary Date: Fri, 9 Jun 2000 06:14:39 +0000 Subject: * sysdeps/i386/bp-asm.h: New file. * sysdeps/i386/__longjmp.S: Define & use symbolic argument stack offsets. Add ENTER/LEAVE macros for optionally maintaining frame-pointer chain when debugging. * sysdeps/i386/add_n.S: Likewise. * sysdeps/i386/addmul_1.S: Likewise. * sysdeps/i386/lshift.S: Likewise. * sysdeps/i386/memchr.S: Likewise. * sysdeps/i386/memcmp.S: Likewise. * sysdeps/i386/mul_1.S: Likewise. * sysdeps/i386/rawmemchr.S: Likewise. * sysdeps/i386/rshift.S: Likewise. * sysdeps/i386/stpcpy.S: Likewise. * sysdeps/i386/stpncpy.S: Likewise. * sysdeps/i386/strchr.S: Likewise. * sysdeps/i386/strchrnul.S: Likewise. * sysdeps/i386/strcspn.S: Likewise. * sysdeps/i386/strpbrk.S: Likewise. * sysdeps/i386/strrchr.S: Likewise. * sysdeps/i386/strspn.S: Likewise. * sysdeps/i386/strtok.S: Likewise. * sysdeps/i386/sub_n.S: Likewise. * sysdeps/i386/submul_1.S: Likewise. * sysdeps/i386/elf/setjmp.S: Likewise. * sysdeps/i386/i486/strcat.S: Likewise. * sysdeps/i386/i486/strlen.S: Likewise. * sysdeps/i386/i586/add_n.S: Likewise. * sysdeps/i386/i586/lshift.S: Likewise. * sysdeps/i386/i586/memcpy.S: Likewise. * sysdeps/i386/i586/memset.S: Likewise. * sysdeps/i386/i586/rshift.S: Likewise. * sysdeps/i386/i586/strchr.S: Likewise. * sysdeps/i386/i586/strcpy.S: Likewise. * sysdeps/i386/i586/strlen.S: Likewise. * sysdeps/i386/i586/sub_n.S: Likewise. * sysdeps/i386/i686/add_n.S: Likewise. * sysdeps/i386/i686/memcpy.S: Likewise. * sysdeps/i386/i686/mempcpy.S: Likewise. * sysdeps/i386/i686/memset.S: Likewise. * sysdeps/i386/i686/strcmp.S: Likewise. 2000-06-08 Greg McGary * sysdeps/i386/bp-asm.h: New file. * sysdeps/i386/__longjmp.S: Define & use symbolic argument stack offsets. Add ENTER/LEAVE macros for optionally maintaining frame-pointer chain when debugging. * sysdeps/i386/add_n.S: Likewise. * sysdeps/i386/addmul_1.S: Likewise. * sysdeps/i386/lshift.S: Likewise. * sysdeps/i386/memchr.S: Likewise. * sysdeps/i386/memcmp.S: Likewise. * sysdeps/i386/mul_1.S: Likewise. * sysdeps/i386/rawmemchr.S: Likewise. * sysdeps/i386/rshift.S: Likewise. * sysdeps/i386/stpcpy.S: Likewise. * sysdeps/i386/stpncpy.S: Likewise. * sysdeps/i386/strchr.S: Likewise. * sysdeps/i386/strchrnul.S: Likewise. * sysdeps/i386/strcspn.S: Likewise. * sysdeps/i386/strpbrk.S: Likewise. * sysdeps/i386/strrchr.S: Likewise. * sysdeps/i386/strspn.S: Likewise. * sysdeps/i386/strtok.S: Likewise. * sysdeps/i386/sub_n.S: Likewise. * sysdeps/i386/submul_1.S: Likewise. * sysdeps/i386/elf/setjmp.S: Likewise. * sysdeps/i386/i486/strcat.S: Likewise. * sysdeps/i386/i486/strlen.S: Likewise. * sysdeps/i386/i586/add_n.S: Likewise. * sysdeps/i386/i586/lshift.S: Likewise. * sysdeps/i386/i586/memcpy.S: Likewise. * sysdeps/i386/i586/memset.S: Likewise. * sysdeps/i386/i586/rshift.S: Likewise. * sysdeps/i386/i586/strchr.S: Likewise. * sysdeps/i386/i586/strcpy.S: Likewise. * sysdeps/i386/i586/strlen.S: Likewise. * sysdeps/i386/i586/sub_n.S: Likewise. * sysdeps/i386/i686/add_n.S: Likewise. * sysdeps/i386/i686/memcpy.S: Likewise. * sysdeps/i386/i686/mempcpy.S: Likewise. * sysdeps/i386/i686/memset.S: Likewise. * sysdeps/i386/i686/strcmp.S: Likewise. --- sysdeps/i386/memchr.S | 57 +++++++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 27 deletions(-) (limited to 'sysdeps/i386/memchr.S') diff --git a/sysdeps/i386/memchr.S b/sysdeps/i386/memchr.S index 1750aa8..80b2107 100644 --- a/sysdeps/i386/memchr.S +++ b/sysdeps/i386/memchr.S @@ -1,7 +1,7 @@ -/* memchr (str, ch, n) -- Return pointer to first occurrence of CH in STR less - than N. +/* memchr (str, chr, len) -- Return pointer to first occurrence of CHR in STR less + than LEN. For Intel 80x86, x>=3. - Copyright (C) 1994, 1995, 1996, 1997, 1998 Free Software Foundation, Inc. + Copyright (C) 1994, 1995, 1996, 1997, 1998, 2000 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper Optimised a little by Alan Modra @@ -32,32 +32,34 @@ #include #include "asm-syntax.h" +#include "bp-asm.h" -/* - INPUT PARAMETERS: - str (sp + 4) - c (sp + 8) - len (sp + 12) -*/ +#define PARMS LINKAGE+8 /* space for 2 saved regs */ +#define RTN PARMS +#define STR RTN+RTN_SIZE +#define CHR STR+PTR_SIZE +#define LEN CHR+4 .text ENTRY (memchr) + ENTER + /* Save callee-safe registers used in this function. */ pushl %esi pushl %edi /* Load parameters into registers. */ - movl 12(%esp), %eax /* str: pointer to memory block. */ - movl 16(%esp), %edx /* c: byte we are looking for. */ - movl 20(%esp), %esi /* len: length of memory block. */ + movl STR(%esp), %eax /* str: pointer to memory block. */ + movl CHR(%esp), %edx /* c: byte we are looking for. */ + movl LEN(%esp), %esi /* len: length of memory block. */ /* If my must not test more than three characters test them one by one. This is especially true for 0. */ cmpl $4, %esi jb L(3) - /* At the moment %edx contains C. What we need for the - algorithm is C in all bytes of the dword. Avoid + /* At the moment %edx contains CHR. What we need for the + algorithm is CHR in all bytes of the dword. Avoid operations on 16 bit words because these require an prefix byte (and one more cycle). */ movb %dl, %dh /* Now it is 0|0|c|c */ @@ -117,9 +119,9 @@ ENTRY (memchr) into bit 32 (=carry flag), so all of the hole bits will be changed. - 3) But wait! Aren't we looking for C, not zero? + 3) But wait! Aren't we looking for CHR, not zero? Good point. So what we do is XOR LONGWORD with a longword, - each of whose bytes is C. This turns each byte that is C + each of whose bytes is CHR. This turns each byte that is CHR into a zero. */ @@ -152,7 +154,7 @@ L(1): movl (%eax), %ecx /* get word (= 4 bytes) in question */ incl %edi /* add 1: if one carry bit was *not* set the addition will not result in 0. */ - /* If at least one byte of the word is C we don't get 0 in %edi. */ + /* If at least one byte of the word is CHR we don't get 0 in %edi. */ jnz L(8) /* found it => return pointer */ /* This process is unfolded four times for better performance. @@ -169,7 +171,7 @@ L(1): movl (%eax), %ecx /* get word (= 4 bytes) in question */ addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(7) /* highest byte is C => return pointer */ + jnc L(7) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -183,7 +185,7 @@ L(1): movl (%eax), %ecx /* get word (= 4 bytes) in question */ addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(6) /* highest byte is C => return pointer */ + jnc L(6) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -197,7 +199,7 @@ L(1): movl (%eax), %ecx /* get word (= 4 bytes) in question */ addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(5) /* highest byte is C => return pointer */ + jnc L(5) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -220,7 +222,7 @@ L(2): subl $16, %esi addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(8) /* highest byte is C => return pointer */ + jnc L(8) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -238,7 +240,7 @@ L(2): subl $16, %esi addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(8) /* highest byte is C => return pointer */ + jnc L(8) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -256,7 +258,7 @@ L(2): subl $16, %esi addl %ecx, %edi /* add the magic value to the word. We get carry bits reported for each byte which is *not* 0 */ - jnc L(8) /* highest byte is C => return pointer */ + jnc L(8) /* highest byte is CHR => return pointer */ xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ orl $0xfefefeff, %edi /* set all non-carry bits */ incl %edi /* add 1: if one carry bit was *not* set @@ -268,19 +270,19 @@ L(2): subl $16, %esi L(3): andl $3, %esi /* mask out uninteresting bytes */ jz L(4) /* no remaining bytes => return NULL */ - cmpb %dl, (%eax) /* compare byte with C */ + cmpb %dl, (%eax) /* compare byte with CHR */ je L(9) /* equal, than return pointer */ incl %eax /* increment source pointer */ decl %esi /* decrement length */ jz L(4) /* no remaining bytes => return NULL */ - cmpb %dl, (%eax) /* compare byte with C */ + cmpb %dl, (%eax) /* compare byte with CHR */ je L(9) /* equal, than return pointer */ incl %eax /* increment source pointer */ decl %esi /* decrement length */ jz L(4) /* no remaining bytes => return NULL */ - cmpb %dl, (%eax) /* compare byte with C */ + cmpb %dl, (%eax) /* compare byte with CHR */ je L(9) /* equal, than return pointer */ L(4): /* no byte found => return NULL */ @@ -312,5 +314,6 @@ L(8): testb %cl, %cl /* test first byte in dword */ L(9): popl %edi /* pop saved registers */ popl %esi - ret + LEAVE + RET_PTR END (memchr) -- cgit v1.1