arch/m32r/lib/strlen.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *  linux/arch/m32r/strlen.S --  strlen code.
   4  *
   5  *  Copyright (C) 2001  Hirokazu Takata
   6  *
   7  *  size_t strlen(const char *s);
   8  *
   9  */
  10
  11 #include <linux/linkage.h>
  12 #include <asm/assembler.h>
  13
  14 #ifdef CONFIG_ISA_DUAL_ISSUE
  15
  16         .text
  17 ENTRY(strlen)
  18         mv      r6, r0              ||  ldi     r2, #0
  19         and3    r0, r0, #3
  20         bnez    r0, strlen_byte
  21 ;
  22 strlen_word:
  23         ld      r0, @r6+
  24 ;
  25         seth    r5, #high(0x01010101)
  26         or3     r5, r5, #low(0x01010101)
  27         sll3    r7, r5, #7
  28 strlen_word_loop:
  29         ld      r1, @r6+            ||  not     r4, r0
  30         sub     r0, r5              ||  and     r4, r7
  31         and     r4, r0
  32         bnez    r4, strlen_last_bytes
  33         ld      r0, @r6+            ||  not     r4, r1
  34         sub     r1, r5              ||  and     r4, r7
  35         and     r4, r1              ||  addi    r2, #4
  36         bnez    r4, strlen_last_bytes
  37         addi    r2, #4              ||  bra.s   strlen_word_loop
  38
  39         ; NOTE: If a null char. exists, return 0.
  40         ; if ((x - 0x01010101) & ~x & 0x80808080)
  41         ;     return 0;
  42 ;
  43 strlen_byte:
  44         ldb     r1, @r6             ||  addi    r6, #1
  45         beqz    r1, strlen_exit
  46         addi    r2, #1              ||  bra.s   strlen_byte
  47 ;
  48 strlen_last_bytes:
  49         ldi     r0, #4              ||  addi    r6, #-8
  50 ;
  51 strlen_byte_loop:
  52         ldb     r1, @r6             ||  addi    r6, #1
  53         addi    r0, #-1             ||  cmpz    r1
  54         bc.s    strlen_exit         ||  cmpz    r0
  55         addi    r2, #1              ||  bnc.s   strlen_byte_loop
  56 ;
  57 strlen_exit:
  58         mv      r0, r2              ||  jmp     r14
  59
  60 #else /* not CONFIG_ISA_DUAL_ISSUE */
  61
  62         .text
  63 ENTRY(strlen)
  64         mv      r6, r0
  65         ldi     r2, #0
  66         and3    r0, r0, #3
  67         bnez    r0, strlen_byte
  68 ;
  69 strlen_word:
  70         ld      r0, @r6+
  71 ;
  72         seth    r5, #high(0x01010101)
  73         or3     r5, r5, #low(0x01010101)
  74         sll3    r7, r5, #7
  75 strlen_word_loop:
  76         ld      r1, @r6+
  77         not     r4, r0          ; NOTE: If a null char. exists, return 0.
  78         sub     r0, r5          ; if ((x - 0x01010101) & ~x & 0x80808080)
  79         and     r4, r7          ;     return 0;
  80         and     r4, r0
  81         bnez    r4, strlen_last_bytes
  82         addi    r2, #4
  83 ;
  84         ld      r0, @r6+
  85         not     r4, r1          ; NOTE: If a null char. exists, return 0.
  86         sub     r1, r5          ; if ((x - 0x01010101) & ~x & 0x80808080)
  87         and     r4, r7          ;     return 0;
  88         and     r4, r1
  89         bnez    r4, strlen_last_bytes
  90         addi    r2, #4
  91         bra     strlen_word_loop
  92 ;
  93 strlen_byte:
  94         ldb     r1, @r6
  95         addi    r6, #1
  96         beqz    r1, strlen_exit
  97         addi    r2, #1
  98         bra     strlen_byte
  99 ;
 100 strlen_last_bytes:
 101         ldi     r0, #4
 102         addi    r6, #-8
 103 ;
 104 strlen_byte_loop:
 105         ldb     r1, @r6
 106         addi    r6, #1
 107         addi    r0, #-1
 108         beqz    r1, strlen_exit
 109         addi    r2, #1
 110         bnez    r0, strlen_byte_loop
 111 ;
 112 strlen_exit:
 113         mv      r0, r2
 114         jmp     r14
 115
 116 #endif /* not CONFIG_ISA_DUAL_ISSUE */
 117
 118         .end