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@cab404 cab404/hw.asm
Last active Aug 29, 2015

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; 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
; 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
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