.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, esi
    sub eax, ecx            # eax = src - nbytes
    cmp edi, eax
    jl  rightcpy
    mov edx, [esi] + ecx            # edx = src + btytes
    cmp eax, edx
    jg  rightcpy
    jmp leftcpy

leftcpy:
    std

rightcpy:
rep movsb
    cld
    mov esp, ebp
    pop ebp
    ret

.end


Gcc Errors:

ex1.s: Assembler messages:
ex1.s:8: Error: ambiguous operand size or operands invalid for `push'
ex1.s:10: Error: `edi' not allowed with `movb'
ex1.s:11: Error: `esi' not allowed with `movb'
ex1.s:17: Error: invalid use of register
ex1.s:29: Error: ambiguous operand size or operands invalid for `pop'