BitwiseInfo/bitcount.asm at main · ScriptScorpion/BitwiseInfo · GitHub

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section .data
    prompt: db "Enter number: ", 0
    returns: db " returns ", 0
    units: db " units, ", 0
    zeros: db " zeros, ", 0
    amount: db " amount of bits", 10, 0
section .bss
    num: resb 10
section .text
    global _start
_start:
    ; Print prompt
    mov rax, 1          ; syscall: write
    mov rdi, 1          ; file descriptor: stdout
    mov rsi, prompt     ; pointer to message
    mov rdx, 14         ; message length
    syscall

    ; Read number
    mov rax, 0          ; syscall: read
    mov rdi, 0          ; file descriptor: stdin
    mov rsi, num        ; buffer to store input
    mov rdx, 10         ; number of bytes to read
    syscall

    mov rsi, num
    xor rax, rax
    xor rcx, rcx
    call convert_loop   ; convert to normal value

    mov rdi, [num]
    call std_print_num_dec

    mov rax, 1
    mov rdi, 1
    mov rsi, returns
    mov rdx, 9
    syscall

    ; Call onecount, zerocount, whole_amount
    mov rax, [num]
    call onecount
    mov r8, rax

    mov rax, [num]
    call zerocount
    mov r9, rax

    mov rax, [num]
    call whole_amount
    mov r10, rax

    mov rdi, r8
    call std_print_num_dec

    mov rax, 1
    mov rdi, 1
    mov rsi, units
    mov rdx, 9
    syscall

    mov rdi, r9
    call std_print_num_dec

    mov rax, 1
    mov rdi, 1
    mov rsi, zeros
    mov rdx, 9
    syscall

    mov rdi, r10
    call std_print_num_dec

    mov rax, 1
    mov rdi, 1
    mov rsi, amount
    mov rdx, 16
    syscall
    ; Exit
    jmp exit

onecount:
    ; Input: rax = number
    ; Output: rax = count of 1s
    xor rcx, rcx
.loop1:
    test rax, rax
    jz .done1
    test rax, 1
    jz .skip1
    inc rcx
.skip1:
    shr rax, 1
    jmp .loop1
.done1:
    mov rax, rcx
    ret

zerocount:
    ; Input: rax = number
    ; Output: rax = count of 0s
    xor rcx, rcx
.loop2:
    test rax, rax
    jz .done2
    test rax, 1
    jnz .skip2
    inc rcx
.skip2:
    shr rax, 1
    jmp .loop2
.done2:
    mov rax, rcx
    ret

whole_amount:
    ; Input: rax = number
    ; Output: rax = total bits
    xor rcx, rcx
.loop3:
    test rax, rax
    jz .done3
    inc rcx
    shr rax, 1
    jmp .loop3
.done3:
    mov rax, rcx
    ret

std_print_num_dec:
    push     rbx // size of number counter
    mov     rax, rdi
    mov     rcx, 0xA
    dec     rsp ; leave space for new value
    mov     rbx, 1
.loop:
    xor     rdx, rdx
    div     rcx
    add     dl, 0x30
    dec     rsp ; leave space for new value
    inc     rbx
    mov     BYTE [rsp], dl
    cmp     rax, 0x0
    jne     .loop

    mov     rax, 1
    mov     rdi, 1
    mov     rsi, rsp
    mov     rdx, rbx
    syscall

    add     rsp, rbx ; put stack into his original position
    pop     rbx
    ret

convert_loop:
    mov cl, [rsi]
    cmp cl, 0x0A
    je .convert_done
    sub cl, '0'
    imul rax, 10
    add rax, rcx
    inc rsi
    jmp convert_loop

.convert_done:
    mov [num], rax
    ret

exit:
    mov rax, 60
    xor rdi, rdi
    syscall