hw.asm

                              ; cab404: int to str, with negative numbers and stuff
global _start

section .data
      test_data: dq -192734, 23400, -9223372036854775808, 9223372036854775807
      test_len: equ ($-test_data)/8

section .bss
      buf: resb 50            ; buffer, so we can print what we got.
      buf_len: equ $-buf

section .text
      _start:

      mov rcx, test_len       ; loading test data
      mov rsi, test_data      ; and its length

      main_calcloop:
        cld                   ; cleaning direction flag before loading
        lodsq                 ; loading next test number into rax

        push rsi              ; preserving registers before call
        push rcx

        mov rdi, buf          ; moving buffer to rbx
        call int_to_str       ; calling convertion
        call printbuf         ; printing buffer
        call ln               ; cleaning buffer and printing LF

        pop rcx               ; regaining registers
        pop rsi

      loop main_calcloop

      call exit

clbuf:                        ; cleaning buffer
    cld
    mov rdi, buf
    mov rcx, buf_len
    xor rax, rax
    rep stosb
ret

ln:                           ; cleaning buffer and writing new line
    call clbuf
    mov rsi, buf
    mov [rsi], byte 10
    call printbuf
ret

printbuf:                     ; printing buffer
    mov	rax, 4		            ; write command for syscall
    mov	rbx, 1		            ; cout
    mov rcx, buf              ; string
    mov rdx, buf_len          ; length
    int	80h                   ; interrupt 80 hex, call kernel
ret



exit:                          ; exits program with 0
    mov	ebx, 0		             ; exit code, 0=normal
    mov	eax, 1		             ; exit command to kernel
    int	0x80	  	             ; interrupt 80 hex, call kernel
ret

; rax - number
; rdi - target string buffer
int_to_str:
    mov cl, 0                  ; using rcx as sign store, defaulting to 0 (+)
    test rax, rax
    jns int_to_str_sign_test   ; checking if rax is negative
      not rax                  ; converting from negative to positive
      inc rax                  ; and adding one because of offset
      mov rcx, '-'             ; setting sign
    int_to_str_sign_test:

    push 0                     ; analog of null terminator, indicates end of stack
    mov rbx, 10                ; we're doing this at base 10

    int_to_str_loop:
      xor rdx, rdx             ; nulling rdx , so no garbage will bother us
      idiv rbx                 ; dividing rax by 10, now rdx has remainder
      add dl, '0'              ; converting remainder to ASCII
      push rdx                 ; pushing digit converted to character
      test rax, rax            ; checking if divident is zero
    jnz int_to_str_loop

    test rcx, rcx              ; checking sign,
    jz int_to_str_write_loop   ; and if it is not zero,
    push rcx                   ; then pushing it.

    int_to_str_write_loop:
      pop rax                  ; popping characters
      test rax, rax            ; until zero is returned
      jz int_to_str_write_loop_break
      stosb
    jmp int_to_str_write_loop

    int_to_str_write_loop_break:

ret

; rax - number
; rdi - target string buffer
int_to_str_ns:
    push 0                     ; analog of null terminator, indicates end of stack
    mov rbx, 10                ; we're doing this at base 10

    int_to_str_ns_loop:
      xor rdx, rdx             ; nulling rdx , so no garbage will bother us
      idiv rbx                 ; dividing rax by 10, now rdx has remainder
      add dl, '0'              ; converting remainder to ASCII
      push rdx                 ; pushing digit converted to character
      test rax, rax            ; checking if divident is zero
    jnz int_to_str_ns_loop

    int_to_str_ns_write_loop:
      pop rax                  ; popping characters
      test rax, rax            ; until zero is returned
      jz int_to_str_ns_write_loop_break
      stosb
    jmp int_to_str_ns_write_loop

    int_to_str_ns_write_loop_break:

ret

int_to_str.asm

; rax - number
; rdi - target string buffer
int_to_str:
    mov cl, 0                  ; using rcx as sign store, defaulting to 0 (+)
    test rax, rax
    jns int_to_str_sign_test   ; checking if rax is negative
      not rax                  ; converting from negative to positive
      inc rax                  ; and adding one because of offset
      mov rcx, '-'             ; setting sign
    int_to_str_sign_test:

    push 0                     ; analog of null terminator, indicates end of stack
    mov rbx, 10                ; we're doing this at base 10

    int_to_str_loop:
      xor rdx, rdx             ; nulling rdx , so no garbage will bother us
      idiv rbx                 ; dividing rax by 10, now rdx has remainder
      add dl, '0'              ; converting remainder to ASCII
      push rdx                 ; pushing digit converted to character
      test rax, rax            ; checking if divident is zero
    jnz int_to_str_loop

    test rcx, rcx              ; checking sign,
    jz int_to_str_write_loop   ; and if it is not zero,
    push rcx                   ; then pushing it.

    int_to_str_write_loop:
      pop rax                  ; popping characters
      test rax, rax            ; until zero is returned
      jz int_to_str_write_loop_break
      stosb
    jmp int_to_str_write_loop

    int_to_str_write_loop_break:

ret

int_to_str_neg.asm

; rax - number
; rdi - target string buffer
int_to_str_ns:
    push 0                     ; analog of null terminator, indicates end of stack
    mov rbx, 10                ; we're doing this at base 10

    int_to_str_ns_loop:
      xor rdx, rdx             ; nulling rdx , so no garbage will bother us
      idiv rbx                 ; dividing rax by 10, now rdx has remainder
      add dl, '0'              ; converting remainder to ASCII
      push rdx                 ; pushing digit converted to character
      test rax, rax            ; checking if divident is zero
    jnz int_to_str_ns_loop

    int_to_str_ns_write_loop:
      pop rax                  ; popping characters
      test rax, rax            ; until zero is returned
      jz int_to_str_ns_write_loop_break
      stosb
    jmp int_to_str_ns_write_loop

    int_to_str_ns_write_loop_break:

ret