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authorGreg McGary <greg@mcgary.org>2000-06-09 06:14:39 +0000
committerGreg McGary <greg@mcgary.org>2000-06-09 06:14:39 +0000
commit3f02f778cdbec7d95e0a9d6f9368ce9cda0a6d03 (patch)
treea193d5f40640e64b7b6555e831772c1934e2a8d0 /sysdeps/i386/memchr.S
parenta40fb915f89d0e225058c0865de4504f83f90173 (diff)
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* 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 <greg@mcgary.org> * 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.
Diffstat (limited to 'sysdeps/i386/memchr.S')
-rw-r--r--sysdeps/i386/memchr.S57
1 files changed, 30 insertions, 27 deletions
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 <drepper@gnu.ai.mit.edu>
Optimised a little by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
@@ -32,32 +32,34 @@
#include <sysdep.h>
#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)