Assembly Language for Beginners

(Jeff_L) #1

3.4. FIBONACCI NUMBERS


3.4.1 Example #1.


The implementation is simple. This program generates the sequence until 21.


#include <stdio.h>


void fib (int a, int b, int limit)
{
printf ("%d\n", a+b);
if (a+b > limit)
return;
fib (b, a+b, limit);
};


int main()
{
printf ("0\n1\n1\n");
fib (1, 1, 20);
};


Listing 3.4: MSVC 2010 x86

_a$ = 8 ; size = 4
_b$ = 12 ; size = 4
_limit$ = 16 ; size = 4
_fib PROC
push ebp
mov ebp, esp
mov eax, DWORD PTR _a$[ebp]
add eax, DWORD PTR _b$[ebp]
push eax
push OFFSET $SG2643
call DWORD PTR impprintf
add esp, 8
mov ecx, DWORD PTR _a$[ebp]
add ecx, DWORD PTR _b$[ebp]
cmp ecx, DWORD PTR _limit$[ebp]
jle SHORT $LN1@fib
jmp SHORT $LN2@fib
$LN1@fib:
mov edx, DWORD PTR _limit$[ebp]
push edx
mov eax, DWORD PTR _a$[ebp]
add eax, DWORD PTR _b$[ebp]
push eax
mov ecx, DWORD PTR _b$[ebp]
push ecx
call _fib
add esp, 12
$LN2@fib:
pop ebp
ret 0
_fib ENDP


_main PROC
push ebp
mov ebp, esp
push OFFSET $SG2647 ; "0\n1\n1\n"
call DWORD PTR impprintf
add esp, 4
push 20
push 1
push 1
call _fib
add esp, 12
xor eax, eax
pop ebp
ret 0
_main ENDP

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