x86_64/string.s

   1 format ELF64
   2
   3 public memcpy
   4 memcpy:
   5         mov     rax, rdi
   6         mov     rcx, rdx
   7         cld
   8         rep movsb
   9         ret
  10
  11 public memmove
  12 memmove:
  13         mov     rcx, rdx
  14         cmp     rdi, rsi
  15         jng     .usual
  16         mov     rax, rsi
  17         add     rax, rcx
  18         cmp     rdi, rax
  19         jg      .usual
  20
  21         mov     rax, rdi
  22         std
  23         add     rsi, rcx
  24         add     rdi, rcx
  25         dec     rsi
  26         dec     rdi
  27         rep movsb
  28         ret
  29 .usual:
  30         mov     rax, rdi
  31         cld
  32         rep movsb
  33         ret
  34
  35 public memset
  36 memset:
  37         mov     rcx, rdx
  38         mov     rax, rsi
  39         mov     rdx, rdi
  40         cld
  41         rep stosb
  42         mov     rax, rdx
  43         ret
  44
  45 public memchr
  46 memchr:
  47         mov     rax, rsi
  48         mov     rcx, rdx
  49         cld
  50         repnz scasb
  51         jne     .failed
  52         mov     rax, rdi
  53         dec     rax
  54         ret
  55 .failed:
  56         xor     eax, eax
  57         ret
  58
  59 public memcmp
  60 memcmp:
  61         xor     eax, eax
  62         mov     rcx, rdx
  63         jecxz   .ret
  64
  65         cld
  66         rep cmpsb
  67         jz      .ret
  68         xor     eax, eax
  69         mov     al, [rdi - 1]
  70         xor     ecx, ecx
  71         mov     cl, [rsi - 1]
  72         sub     eax, ecx
  73 .ret:
  74         ret
  75
  76 public strlen
  77 strlen:
  78         xor     eax, eax
  79         mov     rcx, -1
  80         cld
  81         repnz scasb
  82         mov     rax, rcx
  83         not     rax
  84         dec     rax
  85         ret
  86
  87 public memrchr
  88 memrchr:
  89         mov     eax, esi
  90         mov     rcx, rdx
  91         add     rdi, rcx
  92         dec     rdi
  93         std
  94         repnz scasb
  95         jne     .failed
  96         mov     rax, rdi
  97         inc     rax
  98         ret
  99 .failed:
 100         xor     eax, eax
 101         ret
 102
 103 public strchr
 104 strchr:
 105 .loop:
 106         mov     al, [rdi]
 107         cmp     al, sil
 108         jz      .done
 109         inc     rdi
 110         test    al, al
 111         jnz     .loop
 112         xor     edi, edi
 113 .done:
 114         mov     rax, rdi
 115         ret
 116
 117 public strcmp
 118 strcmp:
 119         xor     eax, eax
 120 .loop:
 121         mov     al, [rdi]
 122         cmp     al, [rsi]
 123         jnz     .ret
 124         inc     rdi
 125         inc     rsi
 126         test    al, al
 127         jnz     .loop
 128         ret
 129 .ret:
 130         movzx   rcx, byte [rsi]
 131         sub     rax, rcx
 132         ret
 133
 134 public strcpy
 135 strcpy:
 136         mov     rdx, rdi
 137         cld
 138 .loop:
 139         lodsb
 140         stosb
 141         or      al, al
 142         jnz     .loop
 143         mov     rax, rdx
 144         ret
 145
 146 public strrchr
 147 strrchr:
 148         xor     edx, edx
 149         dec     rdi
 150 .loop:
 151         inc     rdi
 152         mov     al, [rdi]
 153         test    al, al
 154         jz      .done
 155         cmp     al, sil
 156         jnz     .loop
 157         mov     rdx, rdi
 158         jmp     .loop
 159 .done:
 160         mov     rax, rdx
 161         ret
 162
 163 public strncmp
 164 strncmp:
 165         xor     eax, eax
 166 .loop:
 167         test    rdx, rdx
 168         jz      .failed
 169         mov     al, [rdi]
 170         cmp     al, [rsi]
 171         jnz     .ret
 172         inc     rsi
 173         inc     rdi
 174         dec     rdx
 175         test    al, al
 176         jnz     .loop
 177 .failed:
 178         xor     eax, eax
 179         ret
 180 .ret:
 181         movzx   ecx, byte [rsi]
 182         sub     eax, ecx
 183         ret