arm/string.s

   1
   2 .global memcpy
   3 memcpy:
   4         mov     r12, r0
   5 .loop:
   6         subs    r2, r2, #1
   7         bmi     .ret
   8         ldrb    r3, [r1], #1
   9         strb    r3, [r0], #1
  10         b       .loop
  11 .ret:
  12         mov     r0, r12
  13         mov     pc, lr
  14
  15 .global memset
  16 memset:
  17         mov     r12, r0
  18 .loop:
  19         subs    r2, r2, #1
  20         bmi     .ret
  21         strb    r1, [r0], #1
  22         b       .loop
  23 .ret:
  24         mov     r0, r12
  25         mov     pc, lr
  26
  27 .global memmove
  28 memmove:
  29         mov     r12, r0
  30         cmp     r0, r1
  31         ble     .fw
  32         add     r3, r1, r2
  33         cmp     r0, r3
  34         bgt     .fw
  35
  36         @ copying the memory in reverse order
  37         add     r0, r0, r2
  38         add     r1, r1, r2
  39 .bw:
  40         subs    r2, r2, #1
  41         bmi     .ret
  42         ldrb    r3, [r1, #-1]!
  43         strb    r3, [r0, #-1]!
  44         b       .bw
  45 .fw:
  46         subs    r2, r2, #1
  47         bmi     .ret
  48         ldrb    r3, [r1], #1
  49         strb    r3, [r0], #1
  50         b       .fw
  51 .ret:
  52         mov     r0, r12
  53         mov     pc, lr
  54
  55 .global memchr
  56 memchr:
  57         subs    r2, r2, #1
  58         bmi     .failed
  59         ldrb    r3, [r0], #1
  60         cmp     r3, r1
  61         bne     memchr
  62         b       .ret
  63 .failed:
  64         mov     r0, #0
  65 .ret:
  66         mov     pc, lr
  67
  68 .global memcmp
  69 memcmp:
  70         subs    r2, r2, #1
  71         bmi     .match
  72         ldrb    r3, [r0], #1
  73         ldrb    r12, [r1], #1
  74         subs    r3, r3, r12
  75         movne   r0, r3
  76         bne     .ret
  77         b       memcmp
  78 .match:
  79         mov     r0, #0
  80 .ret:
  81         mov     pc, lr
  82
  83 .global strlen
  84 strlen:
  85         mov     r2, r0
  86 .loop:
  87         ldrb    r1, [r0], #1
  88         tst     r1, r1
  89         bne     .loop
  90         sub     r0, r0, r2
  91         sub     r0, r0, #1
  92         mov     pc, lr
  93
  94 .global strchr
  95 strchr:
  96         ldrb    r2, [r0], #1
  97         cmp     r1, r2
  98         subeq   r0, r0, #1
  99         beq     .ret
 100         tst     r2, r2
 101         bne     strchr
 102         mov     r0, #0
 103 .ret:
 104         mov     pc, lr
 105
 106 .global strcmp
 107 strcmp:
 108         ldrb    r2, [r0], #1
 109         ldrb    r3, [r1], #1
 110         cmp     r2, #1
 111         cmpcs   r2, r3
 112         beq     strcmp
 113         sub     r0, r2, r3
 114         mov     pc, lr
 115
 116 .global strcpy
 117 strcpy:
 118         mov     r3, r0
 119 .loop:
 120         ldrb    r2, [r1], #1
 121         strb    r2, [r0], #1
 122         tst     r2, r2
 123         bne     .loop
 124         mov     r0, r3
 125 .ret:
 126         mov     pc, lr