zyfeier commented on code in PR #8042: URL: https://github.com/apache/nuttx/pull/8042#discussion_r1064315705
########## libs/libc/machine/risc-v/gnu/arch_strcmp.S: ########## @@ -0,0 +1,184 @@ +/**************************************************************************** + * libs/libc/machine/risc-v/gnu/arch_strcmp.S + * + * 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 FreeBSD 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 "asm.h" + +.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 __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ Review Comment: It's gcc predefined macro. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
