.intel_syntax noprefix

.text

.global amemmove

amemmove:
    push ebp
    mov ebp,esp
    mov edi, BYTE PTR [ebp+8]       // edi = *dest
    mov esi, BYTE PTR [ebp+12]      // esi = *src
    mov ecx, WORD [ebp+16]          // ecx = nbytes
    mov eax, [edi]                  // eax = dest
    mov edx, [esi] - ecx            // edx = src - nbtytes
    cmp eax, edx
    jl  rightcpy
    mov edx, [esi] + ecx            // edx = src + btytes
    cmp eax, edx
    jg  rightcpy
    jmp leftcpy

rightcpy:
rep movsb
    jmp fim


leftcpy:
    pushf
    std
rep movsb
    popf

fim:
    mov esp, ebp
    pop ebp
    ret

.end