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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
*/
/*
* The ascii_strcasecmp() function is a case insensitive versions of strcmp().
* It assumes the ASCII character set and ignores differences in case
* when comparing lower and upper case characters. In other words, it
* behaves as if both strings had been converted to lower case using
* tolower() in the "C" locale on each byte, and the results had then
* been compared using strcmp().
*
* The assembly code below is an optimized version of the following C
* reference:
*
* static const char charmap[] = {
* '\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
* '\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
* '\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
* '\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
* '\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
* '\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
* '\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
* '\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
* '\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
* '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
* '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
* '\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
* '\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
* '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
* '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
* '\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
* '\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
* '\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
* '\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
* '\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
* '\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
* '\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
* '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
* '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
* '\300', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
* '\310', '\311', '\312', '\313', '\314', '\315', '\316', '\317',
* '\320', '\321', '\322', '\323', '\324', '\325', '\326', '\327',
* '\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
* '\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
* '\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
* '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
* '\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
* };
*
* int
* ascii_strcasecmp(const char *s1, const char *s2)
* {
* const unsigned char *cm = (const unsigned char *)charmap;
* const unsigned char *us1 = (const unsigned char *)s1;
* const unsigned char *us2 = (const unsigned char *)s2;
*
* while (cm[*us1] == cm[*us2++])
* if (*us1++ == '\0')
* return (0);
* return (cm[*us1] - cm[*(us2 - 1)]);
* }
*
* The following algorithm, from a 1987 news posting by Alan Mycroft, is
* used for finding null bytes in a word:
*
* #define has_null(word) ((word - 0x01010101) & (~word & 0x80808080))
*
* The following algorithm is used for a wordwise tolower() operation:
*
* unsigned int
* parallel_tolower (unsigned int x)
* {
* unsigned int p;
* unsigned int q;
*
* unsigned int m1 = 0x80808080;
* unsigned int m2 = 0x3f3f3f3f;
* unsigned int m3 = 0x25252525;
*
* q = x & ~m1;// newb = byte & 0x7F
* p = q + m2; // newb > 0x5A --> MSB set
* q = q + m3; // newb < 0x41 --> MSB clear
* p = p & ~q; // newb > 0x40 && newb < 0x5B --> MSB set
* q = m1 & ~x;// byte < 0x80 --> 0x80
* q = p & q; // newb > 0x40 && newb < 0x5B && byte < 0x80 -> 0x80,else 0
* q = q >> 2; // newb > 0x40 && newb < 0x5B && byte < 0x80 -> 0x20,else 0
* return (x + q); // translate uppercase characters to lowercase
* }
*
* Both algorithms have been tested exhaustively for all possible 2^32 inputs.
*/
#include <sys/asm_linkage.h>
! The first part of this algorithm walks through the beginning of
! both strings a byte at a time until the source ptr is aligned to
! a word boundary. During these steps, the bytes are translated to
! lower-case if they are upper-case, and are checked against
! the source string.
ENTRY(ascii_strcasecmp)
.align 32
save %sp, -SA(WINDOWSIZE), %sp
subcc %i0, %i1, %i2 ! s1 == s2 ?
bz .stringsequal ! yup, done, strings equal
andcc %i0, 3, %i3 ! s1 word-aligned ?
bz .s1aligned1 ! yup
sethi %hi(0x80808080), %i4 ! start loading Mycroft's magic1
ldub [%i1 + %i2], %i0 ! s1[0]
ldub [%i1], %g1 ! s2[0]
sub %i0, 'A', %l0 ! transform for faster uppercase check
sub %g1, 'A', %l1 ! transform for faster uppercase check
cmp %l0, ('Z' - 'A') ! s1[0] uppercase?
bleu,a .noxlate11 ! yes
add %i0, ('a' - 'A'), %i0 ! s1[0] = tolower(s1[0])
.noxlate11:
cmp %l1, ('Z' - 'A') ! s2[0] uppercase?
bleu,a .noxlate12 ! yes
add %g1, ('a' - 'A'), %g1 ! s2[0] = tolower(s2[0])
.noxlate12:
subcc %i0, %g1, %i0 ! tolower(s1[0]) != tolower(s2[0]) ?
bne .done ! yup, done
inc %i1 ! s1++, s2++
addcc %i0, %g1, %i0 ! s1[0] == 0 ?
bz .done ! yup, done, strings equal
cmp %i3, 3 ! s1 aligned now?
bz .s1aligned2 ! yup
sethi %hi(0x01010101), %i5 ! start loading Mycroft's magic2
ldub [%i1 + %i2], %i0 ! s1[1]
ldub [%i1], %g1 ! s2[1]
sub %i0, 'A', %l0 ! transform for faster uppercase check
sub %g1, 'A', %l1 ! transform for faster uppercase check
cmp %l0, ('Z' - 'A') ! s1[1] uppercase?
bleu,a .noxlate21 ! yes
add %i0, ('a' - 'A'), %i0 ! s1[1] = tolower(s1[1])
.noxlate21:
cmp %l1, ('Z' - 'A') ! s2[1] uppercase?
bleu,a .noxlate22 ! yes
add %g1, ('a' - 'A'), %g1 ! s2[1] = tolower(s2[1])
.noxlate22:
subcc %i0, %g1, %i0 ! tolower(s1[1]) != tolower(s2[1]) ?
bne .done ! yup, done
inc %i1 ! s1++, s2++
addcc %i0, %g1, %i0 ! s1[1] == 0 ?
bz .done ! yup, done, strings equal
cmp %i3, 2 ! s1 aligned now?
bz .s1aligned3 ! yup
or %i4, %lo(0x80808080),%i4! finish loading Mycroft's magic1
ldub [%i1 + %i2], %i0 ! s1[2]
ldub [%i1], %g1 ! s2[2]
sub %i0, 'A', %l0 ! transform for faster uppercase check
sub %g1, 'A', %l1 ! transform for faster uppercase check
cmp %l0, ('Z' - 'A') ! s1[2] uppercase?
bleu,a .noxlate31 ! yes
add %i0, ('a' - 'A'), %i0 ! s1[2] = tolower(s1[2])
.noxlate31:
cmp %l1, ('Z' - 'A') ! s2[2] uppercase?
bleu,a .noxlate32 ! yes
add %g1, ('a' - 'A'), %g1 ! s2[2] = tolower(s2[2])
.noxlate32:
subcc %i0, %g1, %i0 ! tolower(s1[2]) != tolower(s2[2]) ?
bne .done ! yup, done
inc %i1 ! s1++, s2++
addcc %i0, %g1, %i0 ! s1[2] == 0 ?
bz .done ! yup, done, strings equal
or %i5, %lo(0x01010101),%i5! finish loading Mycroft's magic2
ba .s1aligned4 ! s1 aligned now
andcc %i1, 3, %i3 ! s2 word-aligned ?
! Here, we initialize our checks for a zero byte and decide
! whether or not we can optimize further if we're fortunate
! enough to have a word aligned desintation
.s1aligned1:
sethi %hi(0x01010101), %i5 ! start loading Mycroft's magic2
.s1aligned2:
or %i4, %lo(0x80808080),%i4! finish loading Mycroft's magic1
.s1aligned3:
or %i5, %lo(0x01010101),%i5! finish loading Mycroft's magic2
andcc %i1, 3, %i3 ! s2 word aligned ?
.s1aligned4:
sethi %hi(0x3f3f3f3f), %l2 ! load m2 for parallel tolower()
sethi %hi(0x25252525), %l3 ! load m3 for parallel tolower()
or %l2, %lo(0x3f3f3f3f),%l2! finish loading m2
bz .word4 ! yup, s2 word-aligned
or %l3, %lo(0x25252525),%l3! finish loading m3
add %i2, %i3, %i2 ! start adjusting offset s1-s2
sll %i3, 3, %l6 ! shift factor for left shifts
andn %i1, 3, %i1 ! round s1 pointer down to next word
sub %g0, %l6, %l7 ! shift factor for right shifts
orn %i3, %g0, %i3 ! generate all ones
lduw [%i1], %i0 ! new lower word from s2
srl %i3, %l6, %i3 ! mask for fixing up bytes
sll %i0, %l6, %g1 ! partial unaligned word from s2
orn %i0, %i3, %i0 ! force start bytes to non-zero
nop ! pad to align loop to 16-byte boundary
nop ! pad to align loop to 16-byte boundary
! This is the comparision procedure used if the destination is not
! word aligned, if it is, we use word4 & cmp4
.cmp:
andn %i4, %i0, %l4 ! ~word & 0x80808080
sub %i0, %i5, %l5 ! word - 0x01010101
andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080
bz,a .doload ! null byte in previous aligned s2 word
lduw [%i1 + 4], %i0 ! load next aligned word from s2
.doload:
srl %i0, %l7, %i3 ! byte(s) from new aligned word from s2
or %g1, %i3, %g1 ! merge to get unaligned word from s2
lduw [%i1 + %i2], %i3 ! x1 = word from s1
andn %i3, %i4, %l0 ! q1 = x1 & ~m1
andn %g1, %i4, %l4 ! q2 = x2 & ~m1
add %l0, %l2, %l1 ! p1 = q1 + m2
add %l4, %l2, %l5 ! p2 = q2 + m2
add %l0, %l3, %l0 ! q1 = q1 + m3
add %l4, %l3, %l4 ! q2 = q2 + m3
andn %l1, %l0, %l1 ! p1 = p1 & ~q1
andn %l5, %l4, %l5 ! p2 = p2 & ~q2
andn %i4, %i3, %l0 ! q1 = m1 & ~x1
andn %i4, %g1, %l4 ! q2 = m1 & ~x2
and %l0, %l1, %l0 ! q1 = p1 & q1
and %l4, %l5, %l4 ! q2 = p2 & q2
srl %l0, 2, %l0 ! q1 = q1 >> 2
srl %l4, 2, %l4 ! q2 = q2 >> 2
add %l0, %i3, %i3 ! lowercase word from s1
add %l4, %g1, %g1 ! lowercase word from s2
cmp %i3, %g1 ! tolower(*s1) != tolower(*s2) ?
bne .wordsdiffer ! yup, now find byte that is different
add %i1, 4, %i1 ! s1+=4, s2+=4
andn %i4, %i3, %l4 ! ~word & 0x80808080
sub %i3, %i5, %l5 ! word - 0x01010101
andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080
bz .cmp ! no null-byte in s1 yet
sll %i0, %l6, %g1 ! bytes from old aligned word from s2
! words are equal but the end of s1 has been reached
! this means the strings must be equal
.stringsequal:
ret ! return
restore %g0, %g0, %o0 ! return 0, i.e. strings are equal
nop ! pad
! we have a word aligned source and destination! This means
! things get to go fast!
.word4:
lduw [%i1 + %i2], %i3 ! x1 = word from s1
.cmp4:
andn %i3, %i4, %l0 ! q1 = x1 & ~m1
lduw [%i1], %g1 ! x2 = word from s2
andn %g1, %i4, %l4 ! q2 = x2 & ~m1
add %l0, %l2, %l1 ! p1 = q1 + m2
add %l4, %l2, %l5 ! p2 = q2 + m2
add %l0, %l3, %l0 ! q1 = q1 + m3
add %l4, %l3, %l4 ! q2 = q2 + m3
andn %l1, %l0, %l1 ! p1 = p1 & ~q1
andn %l5, %l4, %l5 ! p2 = p2 & ~q2
andn %i4, %i3, %l0 ! q1 = m1 & ~x1
andn %i4, %g1, %l4 ! q2 = m1 & ~x2
and %l0, %l1, %l0 ! q1 = p1 & q1
and %l4, %l5, %l4 ! q2 = p2 & q2
srl %l0, 2, %l0 ! q1 = q1 >> 2
srl %l4, 2, %l4 ! q2 = q2 >> 2
add %l0, %i3, %i3 ! lowercase word from s1
add %l4, %g1, %g1 ! lowercase word from s2
cmp %i3, %g1 ! tolower(*s1) != tolower(*s2) ?
bne .wordsdiffer ! yup, now find mismatching character
add %i1, 4, %i1 ! s1+=4, s2+=4
andn %i4, %i3, %l4 ! ~word & 0x80808080
sub %i3, %i5, %l5 ! word - 0x01010101
andcc %l5, %l4, %g0 ! (word - 0x01010101) & ~word & 0x80808080
bz,a .cmp4 ! no null-byte in s1 yet
lduw [%i1 + %i2], %i3 ! load word from s1
! words are equal but the end of s1 has been reached
! this means the strings must be equal
.stringsequal4:
ret ! return
restore %g0, %g0, %o0 ! return 0, i.e. strings are equal
.wordsdiffer:
srl %g1, 24, %i2 ! first byte of mismatching word in s2
srl %i3, 24, %i1 ! first byte of mismatching word in s1
subcc %i1, %i2, %i0 ! *s1-*s2
bnz .done ! bytes differ, return difference
srl %g1, 16, %i2 ! second byte of mismatching word in s2
andcc %i1, 0xff, %i0 ! *s1 == 0 ?
bz .done ! yup, done, strings equal
! we know byte 1 is equal, so can compare bytes 1,2 as a group
srl %i3, 16, %i1 ! second byte of mismatching word in s1
subcc %i1, %i2, %i0 ! *s1-*s2
bnz .done ! bytes differ, return difference
srl %g1, 8, %i2 ! third byte of mismatching word in s2
andcc %i1, 0xff, %i0 ! *s1 == 0 ?
bz .done ! yup, done, strings equal
! we know bytes 1, 2 are equal, so can compare bytes 1,2,3 as a group
srl %i3, 8, %i1 ! third byte of mismatching word in s1
subcc %i1, %i2, %i0 ! *s1-*s2
bnz .done ! bytes differ, return difference
andcc %i1, 0xff, %g0 ! *s1 == 0 ?
bz .stringsequal ! yup, done, strings equal
! we know bytes 1,2,3 are equal, so can compare bytes 1,2,3,4 as group
subcc %i3, %g1, %i0 ! *s1-*s2
bz,a .done ! bytes differ, return difference
andcc %i3, 0xff, %i0 ! *s1 == 0, strings equal
.done:
ret ! return
restore %i0, %g0, %o0 ! return 0 or byte difference
SET_SIZE(ascii_strcasecmp)
|
