string.s

   1 format ELF
   2
   3 public memcpy
   4 memcpy:
   5         push    esi
   6         push    edi
   7         mov     edi, [esp+12]
   8         mov     esi, [esp+16]
   9         mov     ecx, [esp+20]
  10         mov     eax, edi
  11         cld
  12         rep movsb
  13         pop     edi
  14         pop     esi
  15         ret
  16
  17 public memmove
  18 memmove:
  19         push    esi
  20         push    edi
  21         mov     edi, [esp+12]
  22         mov     esi, [esp+16]
  23         mov     ecx, [esp+20]
  24         cmp     edi, esi
  25         jng     .usual
  26         mov     eax, esi
  27         add     eax, ecx
  28         cmp     edi, eax
  29         jg      .usual
  30
  31         mov     eax, edi
  32         std
  33         add     esi, ecx
  34         add     edi, ecx
  35         dec     esi
  36         dec     edi
  37         rep movsb
  38         jmp     .ret
  39 .usual:
  40         mov     eax, edi
  41         cld
  42         rep movsb
  43 .ret:
  44         pop     edi
  45         pop     esi
  46         ret
  47
  48 public memset
  49 memset:
  50         push    edi
  51         mov     edi, [esp+8]
  52         mov     eax, [esp+12]
  53         mov     ecx, [esp+16]
  54         mov     edx, edi
  55         cld
  56         rep stosb
  57         pop     edi
  58         mov     eax, edx
  59         ret
  60
  61 public memchr
  62 memchr:
  63         mov     eax, [esp+8]
  64         mov     ecx, [esp+12]
  65         push    edi
  66         mov     edi, [esp+8]
  67         cld
  68         repnz scasb
  69         jne     .failed
  70         mov     eax, edi
  71         dec     eax
  72         jmp     .ret
  73 .failed:
  74         xor     eax, eax
  75 .ret:
  76         pop     edi
  77         ret
  78
  79 public memcmp
  80 memcmp:
  81         push    esi
  82         push    edi
  83         xor     eax, eax
  84         mov     esi, [esp+12]
  85         mov     edi, [esp+16]
  86         mov     ecx, [esp+20]
  87         jecxz   .ret
  88
  89         cld
  90         rep cmpsb
  91         jz      .ret
  92         sbb     eax, eax
  93         or      eax, 1
  94 .ret:
  95         pop     edi
  96         pop     esi
  97         ret
  98
  99 public strlen
 100 strlen:
 101         push    edi
 102         mov     edi, [esp+8]
 103         xor     eax, eax
 104         mov     ecx, -1
 105         cld
 106         repnz scasb
 107         mov     eax, ecx
 108         not     eax
 109         dec     eax
 110         pop     edi
 111         ret
 112
 113 public strchr
 114 strchr:
 115         mov     ecx, [esp+4]
 116         mov     edx, [esp+8]
 117 .loop:
 118         mov     al, [ecx]
 119         cmp     al, dl
 120         jz      .done
 121         inc     ecx
 122         test    al, al
 123         jnz     .loop
 124         xor     ecx, ecx
 125 .done:
 126         mov     eax, ecx
 127         ret
 128
 129 public strcmp
 130 strcmp:
 131         mov     ecx, [esp+4]
 132         mov     edx, [esp+8]
 133         xor     eax, eax
 134 .loop:
 135         mov     al, [ecx]
 136         cmp     al, [edx]
 137         jnz     .ret
 138         inc     edx
 139         inc     ecx
 140         test    al, al
 141         jnz     .loop
 142         ret
 143 .ret:
 144         movzx   ecx, byte [edx]
 145         sub     eax, ecx
 146         ret
 147
 148 public strcpy
 149 strcpy:
 150         push    edi
 151         push    esi
 152         mov     edx, [esp+12]
 153         mov     esi, [esp+16]
 154         mov     edi, edx
 155         cld
 156 .loop:
 157         lodsb
 158         stosb
 159         or      al, al
 160         jnz     .loop
 161         pop     esi
 162         pop     edi
 163         mov     eax, edx
 164         ret