问题
Finally after a long session of countless errors , hope this is the final one.
No Compile or runtime errors, Just a logical error.
EDIT: (Fixed Pseudocode)
My Pseudocode:
first = 1;
second = 1;
third = 0;
for i from 1 to n{
third=first+second
first=second
second=third
}
return third
This would print the final result of the series.
My Assembly Code:
I have added Comments where ever possible
.386
.model flat,stdcall
option casemap:none
.data
timestell db "Loop Ran : %d Times -----",0 ;format string
fmtd db "%d",0
finalprint db "Final Number is : %d ------",0 ;format string
times dd 0Ah ;times to loop
first dd 1h
second dd 1h
third dd 0h
.data?
retvalue1 dd ? ;we will initialize it later
.code
include windows.inc
include user32.inc
includelib user32.lib
include kernel32.inc
includelib kernel32.lib
includelib MSVCRT
extrn printf:near
extrn exit:near
public main
main proc
mov ecx, times ;loop "times" times
mov eax,0 ;just to store number of times loop ran
top: ;body of loop
cmp ecx, 0 ;test at top of loop
je bottom ;loop exit when while condition false
add eax,1 ;Just to test number of times loop ran
mov ebx,first ;move first into ebx
add ebx,second ;add ebx, [ first+second ]
mov third,ebx ;Copy result i.e ebx [first+second] to third
xor ebx,ebx ;clear for further use
mov ebx,first ;move first into ebx
mov second,ebx ;copy ebx to second [NOW second=first]
xor ebx,ebx ;clear for later use
mov ebx,third ;move thirs into ebx
mov second,ebx ;copy ebx to third [NOW second=third]
xor ebx,ebx ;clear it
dec ecx ;decrement loop
jmp top ;Loop again
bottom:
mov retvalue1,eax ;store eax into a variable
push retvalue1 ;pass this variable to printf
push offset timestell ;pass Format string to printf
call printf ;Print no. of times loop ran
push third ;push value of third to printf
push offset finalprint ;push the format string
call printf ;Print the final number
push 0 ;exit gracefully
call exit ;exit system
main endp
end main
The code runs well but the output doesn't satisfies me:
Output: Loop Ran : 10 Times -----Final Number is : 11 ------
First of all i am not really sure that Final number is in decimal or hex form.
- Assuming it as decimal : Fibonacci Series doesn't have 11
- Assuming it as hex : Fibonacci Series doesn't have 17 (11 hex = 17 dec)
What am i doing wrong?
回答1:
The problem was that my Actual code was not matching with my Pseudocode which resulted in the Logical error.
This Part
mov ebx,first ;move first into ebx
mov second,ebx ;copy ebx to second [NOW second=first]
This gives first value of second, but my PseudoCode says "first=second", which means give value of second to first.
mov ebx,second ;move second into ebx
mov first,ebx ;copy ebx to second [NOW first=second]
Final Working Code for x86 Intel Processor:
For any further referrers , i am posting a working code for x86 intel
.386
.model flat,stdcall
option casemap:none
.data
timestell db "Loop Ran : %d Times -----",0 ;format string
finalprint db "%d th Fibonacci number is %d",0 ;format string
times dd 14h ;times to loop
first dd 1h
second dd 1h
third dd 0h
.code
include windows.inc
include user32.inc
includelib user32.lib
include kernel32.inc
includelib kernel32.lib
includelib MSVCRT
extrn printf:near
extrn exit:near
public main
main proc
mov ecx, times ;set loop counter to "times" time
sub ecx,2 ;loop times-2 times
top:
cmp ecx, 0 ; test at top of loop
je bottom ; loop exit when while condition false
xor ebx,ebx ;Clear ebx
mov ebx,first ;move first into ebx
add ebx,second ;add ebx, [ first+second ]
mov third,ebx ;Copy result i.e ebx [first+second] to third
xor ebx,ebx ;clear for further use
mov ebx,second ;move second into ebx
mov first,ebx ;copy ebx to second [NOW first=second]
xor ebx,ebx ;clear for later use
mov ebx,third ;move thirs into ebx
mov second,ebx ;copy ebx to third [NOW second=third]
xor ebx,ebx ;clear it
dec ecx ;decrement loop
jmp top ;Loop again
bottom:
push third
push times ;push value of third to printf
push offset finalprint ;push the format string
call printf ;Print the final number
push 0 ;exit gracefully
call exit ;exit system
main endp
end main
来源：https://stackoverflow.com/questions/35579861/fibonacci-series-in-assembly-x86