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Diffstat (limited to 'newlib/libc/machine/nds32/strcmp.S')
| -rw-r--r-- | newlib/libc/machine/nds32/strcmp.S | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/newlib/libc/machine/nds32/strcmp.S b/newlib/libc/machine/nds32/strcmp.S new file mode 100644 index 000000000..f3f37fb3e --- /dev/null +++ b/newlib/libc/machine/nds32/strcmp.S @@ -0,0 +1,96 @@ +/* +Copyright (c) 2013 Andes Technology Corporation. +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + 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. + + The name of the company may not be used to endorse or promote + products derived from this software without specific prior written + permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 RED HAT INCORPORATED 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. + + + Function: + strcmp - compare two strings. + Syntax: + int strcmp(const char *s1, const char *s2); + Description: + This function compares the two strings s1 and s2. It returns an + integer less than, equal to, or greater than zero if s1 is found, + respectively, to be less than, to match, or be greater than s2. + Return value: + strcmp returns an integer less than, equal to, or greater than + zero if s1 (or the first n bytes thereof) is found, respectively, + to be less than, to match, or be greater than s2. +*/ + .text + .align 2 + .globl strcmp + .type strcmp, @function +strcmp: + /* If s1 or s2 are unaligned, then compare bytes. */ + or $r5, $r1, $r0 + andi $r5, $r5, #3 + bnez $r5, .Lbyte_mode + + /* If s1 and s2 are word-aligned, compare them a word at a time. */ + lwi $r5, [$r0+(0)] + lwi $r3, [$r1+(0)] + bne $r5, $r3, .Lbyte_mode /* A difference was detected, so + search bytewise. */ + + /* It's more efficient to set bit mask outside the word_mode loop. */ + sethi $r4, hi20(0xFEFEFEFF) /* Set $r4 as -0x01010101. */ + ori $r4, $r4, lo12(0xFEFEFEFF) + sethi $r2, hi20(0x80808080) + ori $r2, $r2, lo12(0x80808080) + b .Ldetect_null + +.align 2 +.Lword_mode: + lmw.aim $r5, [$r0], $r5 + lmw.aim $r3, [$r1], $r3 + bne $r5, $r3, .Lbyte_mode + +.Ldetect_null: + /* #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) + DETECTNULL returns nonzero if (long)X contains a NULL byte. */ + nor $r3, $r5, $r5 /* r3 = ~(X) */ + add $r5, $r5, $r4 /* r2 = ((X) - 0x01010101) */ + and $r5, $r5, $r3 /* r2 = ~(X) & ((X) - 0x01010101) */ + and $r5, $r5, $r2 /* r2= r2 & 0x80808080 */ + beqz $r5, .Lword_mode /* No NULL byte, compare next word. */ + + /* To get here, *a1 == *a2, thus if we find a null in *a1, + then the strings must be equal, so return zero. */ + movi $r0, #0 + ret + +.Lbyte_mode: + /* Byte-mode compare. */ + lbi.bi $r5, [$r0], #1 + lbi.bi $r3, [$r1], #1 + bne $r5, $r3, 1f /* Mismatch, done. */ + bnez $r5, .Lbyte_mode +1: + sub $r0, $r5, $r3 + ret + .size strcmp, .-strcmp |