Hello
I am programming in NASM 64bit Assembly. I am doing a project on converting decimal to binary and binary to decimal.
I having trouble with the call printf and converting decimal to binary.
; Convert Decimal to Binary
extern printf
section .bss
decsave: resd 2 ; stores dec->bin conversion
binsave: resd 1
section .data ; preset constants, writeable
dec1: db '1','2','4','.','3','7','5',0
bin1: dq 01010110110101B ; 10101101.10101 note where binary point should be
ten: dq 10
debug: db "debug 124 is %ld", 10, 0
section .text ; instructions, code segment
global main ; for gcc standard linking
main: ; label
push rbp ; save rbp
;parse and convert integer portion of dec->bin
mov rax,0 ; accumulate value here
mov al,[dec1] ; get first ASCII digit
sub al,48 ; convert ASCII digit to binary
mov rbx,0 ; clear register (upper part)
mov bl,[dec1+1] ; get next ASCII digit
sub rbx,48 ; convert ASCII digit to binary
imul rax,10 ; ignore rdx
add rax,rbx ; increment accumulator
mov rbx,0
mov bl,[dec1+2]
sub rbx,48
imul rax,10
add rax,rbx
mov [decsave],rax ; save decimal portion
mov rdi, debug
; mov rsi, [decsave]
mov rsi, 46
mov rax,0
call printf
; return using c-style pops to return stack to correct position
; and registers to correct content
pop rbp
mov rax,0
ret ; return
; print the bits in decsave:
section .bss
abits: resb 17 ; 16 characters & zero terminator
section .data
fmts: db "%s",0
section .text
; shift decimal portion into abits as ascii
mov rax,[decsave] ; restore rax to dec. portion
mov rcx,8 ; for printing 1st 8 bits
loop3: mov rdx,0 ; clear rdx ready for a bit
shld rdx,rax,1 ; top bit of rax into rdx
add rdx,48 ; make it ASCII
mov [abits+rcx-1],dl ; store character
ror rax,1 ; next bit into top of rax
loop loop3 ; decrement rcx, jump non zero
mov byte [abits+7],'.' ; end of dec. portion string
mov byte [abits+8],0 ; end of "C" string
push qword abits ; string to print
push qword fmts ; "%s"
call printf
add rsp,8
mov rax,[decsave+16] ; increment to fractional portion
mov rcx,16 ; for printing 3 bits as required in the directions
loop4: mov rdx,0 ; clear rdx ready for a bit
shld rdx,rax,1 ; top bit of rax into rdx
add rdx,48 ; make it ASCII
mov [abits+rcx-1],dl ; store character
ror rax,1 ; next bit into top of rax
loop loop4 ; decrement rcx, jump non zero
mov byte [abits+3],10 ; end of "C" string at 3 places
mov byte [abits+4],0 ; end of "C" string
push qword abits ; string to print
push qword fmts ; "%s"
call printf
add rsp,8
; Convert Binary to Decimal
section .data
fmtd: db "%d.",0
fmtd2: db "%d",10,0
section .text
;convert binary integer portion to decimal
mov rax, 0 ; clear accumulator
mov rdx, 0 ; clear for bin storage
mov rdx, [bin1]
shld ax, dx, 11 ; shift binary value into rax
mov qword [binsave], rax ; end of "C" string
push qword [binsave] ; string to print
push qword fmtd ; "%d."
call printf
add rsp,8
; convert binary fraction to decimal
mov rbx, 0
mov rdx, [bin1]
shl rdx, 11
shld bx, dx, 5 ; shift fractional portion into bl
mov rdx, 0 ; accumulator
mov al, 1 ; quotient
shl bx, 3 ; place 5 digits at end of bl
mov ch, 0 ; our count
loop5:
cmp ch, 4 ; check to see that we've done all 5 digits
je save3 ; finished
mov cl, 2 ; base to convert from1
mov bh, 0 ; clear bh
imul cl ; multiply to get divisor in (1/32, 1/16,1/8,etc)
shl bx, 1 ; place single digit in bh
cmp bh, 1 ; if if fractional digit is a 1 accumlate value
jne loop5
push rcx ; store rcx (loop counter and base)
push rax ; store rax (divisor)
mov al, 1 ; dividen
pop rcx ; restore divisor for use
push rcx ; save it again for rax
push rdx ; idiv will destroy rdx
mov rdx, 0 ; set quotient
break1:
idiv cl
pop rdx ; restore rdx
add dx, ax
pop rax ; restore rax
pop rcx ; restore rcx
inc ch
jmp loop5
save3:
push qword rdx ; string to print
push qword fmtd2 ;
call printf
add rsp,8
; return using c-style pops to return stack to correct position
; and registers to correct content
pop rbp
mov rax,0
ret ; return
Any suggestions would be helpful.
Thank You
