strlen.S
2.15 KB
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/*
* linux/arch/m32r/strlen.S -- strlen code.
*
* Copyright (C) 2001 Hirokazu Takata
*
* size_t strlen(const char *s);
*
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#ifdef CONFIG_ISA_DUAL_ISSUE
.text
ENTRY(strlen)
mv r6, r0 || ldi r2, #0
and3 r0, r0, #3
bnez r0, strlen_byte
;
strlen_word:
ld r0, @r6+
;
seth r5, #high(0x01010101)
or3 r5, r5, #low(0x01010101)
sll3 r7, r5, #7
strlen_word_loop:
ld r1, @r6+ || not r4, r0
sub r0, r5 || and r4, r7
and r4, r0
bnez r4, strlen_last_bytes
ld r0, @r6+ || not r4, r1
sub r1, r5 || and r4, r7
and r4, r1 || addi r2, #4
bnez r4, strlen_last_bytes
addi r2, #4 || bra.s strlen_word_loop
; NOTE: If a null char. exists, return 0.
; if ((x - 0x01010101) & ~x & 0x80808080)
; return 0;
;
strlen_byte:
ldb r1, @r6 || addi r6, #1
beqz r1, strlen_exit
addi r2, #1 || bra.s strlen_byte
;
strlen_last_bytes:
ldi r0, #4 || addi r6, #-8
;
strlen_byte_loop:
ldb r1, @r6 || addi r6, #1
addi r0, #-1 || cmpz r1
bc.s strlen_exit || cmpz r0
addi r2, #1 || bnc.s strlen_byte_loop
;
strlen_exit:
mv r0, r2 || jmp r14
#else /* not CONFIG_ISA_DUAL_ISSUE */
.text
ENTRY(strlen)
mv r6, r0
ldi r2, #0
and3 r0, r0, #3
bnez r0, strlen_byte
;
strlen_word:
ld r0, @r6+
;
seth r5, #high(0x01010101)
or3 r5, r5, #low(0x01010101)
sll3 r7, r5, #7
strlen_word_loop:
ld r1, @r6+
not r4, r0 ; NOTE: If a null char. exists, return 0.
sub r0, r5 ; if ((x - 0x01010101) & ~x & 0x80808080)
and r4, r7 ; return 0;
and r4, r0
bnez r4, strlen_last_bytes
addi r2, #4
;
ld r0, @r6+
not r4, r1 ; NOTE: If a null char. exists, return 0.
sub r1, r5 ; if ((x - 0x01010101) & ~x & 0x80808080)
and r4, r7 ; return 0;
and r4, r1
bnez r4, strlen_last_bytes
addi r2, #4
bra strlen_word_loop
;
strlen_byte:
ldb r1, @r6
addi r6, #1
beqz r1, strlen_exit
addi r2, #1
bra strlen_byte
;
strlen_last_bytes:
ldi r0, #4
addi r6, #-8
;
strlen_byte_loop:
ldb r1, @r6
addi r6, #1
addi r0, #-1
beqz r1, strlen_exit
addi r2, #1
bnez r0, strlen_byte_loop
;
strlen_exit:
mv r0, r2
jmp r14
#endif /* not CONFIG_ISA_DUAL_ISSUE */
.end