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assemblyx86masm

Convert byte to string in x86 assembly language

In x86 assembly language, is there any efficient way to convert a byte to a string of binary digits (represented as a byte array of 0s and 1s)? As far as I know, there isn't any 'toString' function in x86 assembly, as in most high-level programming languages.

.stack 2048

.data
theString byte 0, 0, 0, 0, 0, 0, 0, 0 ;store eax as a binary string here.
ExitProcess proto, exitcode:dword 

.code
start:
mov eax, 3;
;now I need to convert eax to a binary string somehow (i. e., a byte array of 0s and 1s)
invoke  ExitProcess, 0
end start
Solution

  • Was it that hard?:

    .data
mystr db 33 dup(0)

.code

EaxToBinaryString:
    mov     ebx, offset mystr
    mov     ecx, 32
EaxToBinaryString1:
    mov     dl, '0' ; replace '0' with 0 if you don't want an ASCII string
    rol     eax, 1
    adc     dl, 0
    mov     byte ptr [ebx], dl
    inc     ebx
    loop    EaxToBinaryString1
    ret