diff options
Diffstat (limited to 'newlib/libc/machine/riscv/strcmp.S')
-rw-r--r-- | newlib/libc/machine/riscv/strcmp.S | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/newlib/libc/machine/riscv/strcmp.S b/newlib/libc/machine/riscv/strcmp.S new file mode 100644 index 000000000..2d655ed8e --- /dev/null +++ b/newlib/libc/machine/riscv/strcmp.S @@ -0,0 +1,148 @@ +/* Copyright (c) 2017 SiFive Inc. All rights reserved. + + This copyrighted material is made available to anyone wishing to use, + modify, copy, or redistribute it subject to the terms and conditions + of the BSD License. This program is distributed in the hope that + it will be useful, but WITHOUT ANY WARRANTY expressed or implied, + including the implied warranties of MERCHANTABILITY or FITNESS FOR + A PARTICULAR PURPOSE. A copy of this license is available at + http://www.opensource.org/licenses. +*/ + +#include <sys/asm.h> + +#if BYTE_ORDER != LITTLE_ENDIAN +# error +#endif + +.text +.globl strcmp +.type strcmp, @function +strcmp: + or a4, a0, a1 + li t2, -1 + and a4, a4, SZREG-1 + bnez a4, .Lmisaligned + +#if SZREG == 4 + li a5, 0x7f7f7f7f +#else + ld a5, mask +#endif + + .macro check_one_word i n + REG_L a2, \i*SZREG(a0) + REG_L a3, \i*SZREG(a1) + + and t0, a2, a5 + or t1, a2, a5 + add t0, t0, a5 + or t0, t0, t1 + + bne t0, t2, .Lnull\i + .if \i+1-\n + bne a2, a3, .Lmismatch + .else + add a0, a0, \n*SZREG + add a1, a1, \n*SZREG + beq a2, a3, .Lloop + # fall through to .Lmismatch + .endif + .endm + + .macro foundnull i n + .ifne \i + .Lnull\i: + add a0, a0, \i*SZREG + add a1, a1, \i*SZREG + .ifeq \i-1 + .Lnull0: + .endif + bne a2, a3, .Lmisaligned + li a0, 0 + ret + .endif + .endm + +.Lloop: + # examine full words at a time, favoring strings of a couple dozen chars +#if __riscv_xlen == 32 + check_one_word 0 5 + check_one_word 1 5 + check_one_word 2 5 + check_one_word 3 5 + check_one_word 4 5 +#else + check_one_word 0 3 + check_one_word 1 3 + check_one_word 2 3 +#endif + # backwards branch to .Lloop contained above + +.Lmismatch: + # words don't match, but a2 has no null byte. +#if __riscv_xlen == 64 + sll a4, a2, 48 + sll a5, a3, 48 + bne a4, a5, .Lmismatch_upper + sll a4, a2, 32 + sll a5, a3, 32 + bne a4, a5, .Lmismatch_upper +#endif + sll a4, a2, 16 + sll a5, a3, 16 + bne a4, a5, .Lmismatch_upper + + srl a4, a2, 8*SZREG-16 + srl a5, a3, 8*SZREG-16 + sub a0, a4, a5 + and a1, a0, 0xff + bnez a1, 1f + ret + +.Lmismatch_upper: + srl a4, a4, 8*SZREG-16 + srl a5, a5, 8*SZREG-16 + sub a0, a4, a5 + and a1, a0, 0xff + bnez a1, 1f + ret + +1:and a4, a4, 0xff + and a5, a5, 0xff + sub a0, a4, a5 + ret + +.Lmisaligned: + # misaligned + lbu a2, 0(a0) + lbu a3, 0(a1) + add a0, a0, 1 + add a1, a1, 1 + bne a2, a3, 1f + bnez a2, .Lmisaligned + +1: + sub a0, a2, a3 + ret + + # cases in which a null byte was detected +#if __riscv_xlen == 32 + foundnull 0 5 + foundnull 1 5 + foundnull 2 5 + foundnull 3 5 + foundnull 4 5 +#else + foundnull 0 3 + foundnull 1 3 + foundnull 2 3 +#endif +.size strcmp, .-strcmp + +#if SZREG == 8 +.section .srodata.cst8,"aM",@progbits,8 +.align 3 +mask: +.dword 0x7f7f7f7f7f7f7f7f +#endif |