Random Fun with NASM
Posted by hank, Wed Nov 21 22:45:00 UTC 2007
I was on IRC tonight and someone was having trouble with their NASM homework. I decided to help them by learning NASM and coding up their homework problem for fun. It was pretty cool. Here’s the resultant program:
; Goal: (a+b)*c+d*b
; PARI/GP says:
; ? (1.234+5.678)*9.012+3.456*5.678
; %1 = 81.91411200000000000000000000
;
;=== Output ===
;hank@rofl:/tmp$ nasm -felf floating_point_arith.asm && \
; gcc floating_point_arith.o && ./a.out
;Answer: 81.91411
;===
;QED
extern printf
section .data
a: dq 1.234
b: dq 5.678
c: dq 9.012
d: dq 3.456
e: dq 7.890
fmt: db "Answer: %.5f",10,0
section .bss
f: resq 1
section .text
global main
main:
fldz
fld qword [a]
fadd qword [b]
fmul qword [c]
fstp qword [f]
fld qword [d]
fmul qword [b]
fadd qword [f]
fstp qword [f]
push dword [f+4]
push dword [f]
push dword fmt
call printf
add esp, 12
mov eax, 0
ret
Code is also available here:
http://modzer0.cs.uaf.edu/repos/hank/code/asm/floating_point_arith.asm
All this does is add some floats and call printf, but it was fun to monkey around low-level again.
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