arch/m32r/lib/strlen.S

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