i try to make selection sort in masm but my source print nothing only shows error phrase
maybe findMin PROC make error however i can't modify that block
would u help me? :(((
INCLUDE Irvine32.inc
.data
intArray DWORD - 117, 10, -1231, 2, 5, -11, -16, 7, 8, 9, 10, 1231, 123, 2, 123, 1, -123, 123, 12333, 875, 844, 111
.code
main PROC
mov ecx, LENGTHOF intArray
mov esi, 0
mov edi, 1
mov eax, 0
outer:
call findMin
call swap
inc esi
mov edi,esi
inc edi
loop outer
call printArray
exit
main ENDP
printArray PROC
mov ecx, LENGTHOF intArray
mov esi, 0
L1:
mov eax, intArray[esi * 4]
call writeInt
mov al, ' '
call writeChar
inc esi
Loop L1
call crlf
ret
printArray ENDP
findMin PROC USES esi ecx edi
mov ecx, LENGTHOF intArray
sub ecx, esi; dec unnecessary loop count
inner :
mov eax, intArray[esi * 4]
cmp eax, intArray[edi * 4]
JG tmp
inc edi
loop inner
mov edi, ebx; save min element index to edi
ret
findMin ENDP
tmp : ; save min element index to ebx and change esi
mov ebx, edi
mov esi, edi
ret
swap PROC
mov eax, intArray[esi * 4]
mov ebx, intArray[edi * 4]
xchg eax, ebx
mov intArray[esi * 4], eax
mov intArray[edi * 4], ebx
ret
swap ENDP
END main
main PROC
what i knew jmp isn't save return address then, how to return from jmp?
(i'm sorry everyone , i really bad at eng grammer ;( )
Related
Today I'm working on arrays and addressing modes so I made this snippet to train myself. Everything is working fine (apparently) but I chose the easiest way using fixed size arrays. My question is about dynamic memory allocation. In my code, my arrays arrayand array2 have a fixed size (8 * 4(int)). If I wanted to extend them, or to speak with C concepts, make a realloc or something like depending on real time values for the size, may I have to implement system calls like sys_brk and mmapby myself in assembly
or is there an other option ? The other question deals with the part of my code used to reverse an array (label .reversing) I know they are faster solutions than mine so if you could give me some advices, it would be nice.
%define ARRAY_LEN 8
%macro print 2
mov eax, 4
mov ebx, 1
mov ecx, %1
mov edx, %2
int 0x80
%endmacro
%macro exit 0
xor ebx, ebx
mov eax, 1
int 0x80
%endmacro
section .bss
sumarrays resd 1
dynarray resd 256
section .rodata
highest equ 0x78
evensum equ 0x102
sumarray1 equ 0x1e6
sumarray2 equ 0x256
section .data
revarray times ARRAY_LEN dd 0
strok db "Good result !", 0xa, 0
lenstrok equ $ - strok
strerror db "Bad result !", 0xa, 0
lenerror equ $ - strerror
array dd 0x33, 0x21, 0x32, 0x78, 0x48, 0x77, 0x19, 0x10
array2 dd 0x12, 0x98, 0x65, 0x62, 0x4e, 0x3e, 0x1f, 0x3a
section .text
global sort
global sum
global _start
_start:
; sort array from highest value to lowest value
sub esp, 8
push ARRAY_LEN
push array
call sort
add esp, 8
and esp, 0xfffffff0
; copying array into some another ones : array -> revarray
mov esi, eax
mov edi, revarray
mov ecx, ARRAY_LEN
rep movsd
; now let's reverse the array
mov esi, revarray ;esi = address of array
mov ecx, ARRAY_LEN ;ecx = number of elements
lea edi, [esi + ecx * 4 - 4]
.reversing:
mov eax, [esi] ;eax = value at start
mov ebx, [edi] ;ebx = value at end
mov [edi], eax
mov [esi], ebx
add esi, 4 ;incrementing address of next item at start
sub edi, 4 ;incrementing address of next item at end
cmp esi, edi ;middle reached ?
jb .reversing ;no we continue
.reversed:
;after, we compute the sum of the elements in the array
mov esi, revarray ; address of array
mov edx, ARRAY_LEN ; num elem of array
sub esp, 8
call arraysum ; sum computation
add esp, 8
cmp eax, sumarray1 ; we check the result to be sure
jne .failure
; merging array2 with array
; esi = source address of first array
; edi = address of second array, the destination one
mov esi, array2
mov edi, array
sub esp, 8
call mergearrays
add esp, 8
; we compute the sum of the merged arrays into the new (old one in fact)
mov esi, array
mov ecx, ARRAY_LEN
add esp, 8
call arraysum
add esp, 8
cmp eax, 0x43c ; we check the result to be sure
jne .failure ; if not egal, exit
; compute the sum of even numbers only in the array
; set up edx to 0 at beginning of loop
; cmova edx, $value_even_number
mov esi, revarray
xor ebx, ebx
xor ecx, ecx
.iterate:
xor edx, edx ; setting up edx to 0
mov eax, [esi + ecx * 4]
test al, 1 ; CF == 0 ? so it's an even number
cmovz edx, eax ; we store the value of current element in edx
add ebx, edx ; so in case of odd number => add 0
inc ecx
cmp ecx, ARRAY_LEN ; end of array reached ?
jne .iterate ; no, we continue
cmp ebx, 0x102 ; check if result is good
je .success
jmp .failure
exit
.success:
print strok, lenstrok
exit
.failure:
print strerror, lenerror
exit
; ********************************************
; computes the sum of all elements of an array
; esi = address of the array
; edx = number of elements in array
; output : eax
; ********************************************
arraysum:
push ebx
xor ebx, ebx
xor ecx, ecx
.arraysum:
mov eax, [esi + ecx *4]
add ebx, eax
inc ecx
cmp ecx, edx
je .sumdone
jmp .arraysum
.sumdone:
mov eax, ebx
pop ebx
ret
; *********************************************
; procedure that sort array from highest to lowest value
; first arg = address of the array
; second arg = number of elements in a array
; return : eax, sorted array
; ********************************************
sort:
push ebp
mov ebp, esp
mov edx, [ebp + 12]
.loop1:
mov esi, [ebp + 8]
mov ecx, [ebp + 12]
.loop2:
mov eax, [esi]
mov ebx, [esi + 4]
cmp eax, ebx
jg .skip
mov [esi], ebx
mov [esi + 4], eax
.skip:
add esi, 4 ;perform loop checks
dec ecx
cmp ecx, 1
ja .loop2
dec edx
ja .loop1
mov eax,[ebp + 8] ; save result in eax
mov esp,ebp
pop ebp
ret
; ****************************************************
; function adding two arrays merging them
; esi = address of first array
; edi = address of second array (destination array)
; ****************************************************
mergearrays:
xor ecx, ecx
.merging:
mov eax, [esi + ecx * 4]
xadd [edi + ecx * 4], eax
inc ecx
cmp ecx, ARRAY_LEN
je .mergedone
jmp .merging
.mergedone:
ret
I am trying to get my frequency table to fully display but while trying to run the loop
through the next label it gives me an exception handler error. I am wondering how I can get my loop to run fully
My code:
INCLUDE Irvine32.inc
.data
target BYTE "AAEBDCFBBC", 0
freqTable DWORD 256 DUP(0)
introPrompt BYTE "Here are the indexes in hex and their counts in the array: ", 0ah,
0dh, 0
prompt BYTE "Location ", 0
prompt2 BYTE " : ", 0
numcount DWORD 0
sLength DWORD ?
location DWORD ?
count DWORD 0
temp BYTE ?
.code
main PROC
mov edx, OFFSET target
call StrLength
mov sLength, eax
Get_frequencies PROTO,
pval1: DWORD,
tableVal: DWORD
INVOKE Get_frequencies, ADDR target, ADDR freqTable
mov eax, numCount
call WriteDec
call crlf
mov edx, OFFSET introPrompt
call WriteString
;Writes the frequency table
mov esi, OFFSET freqTable
mov ecx, 256
top:
mov edx, OFFSET prompt
call WriteString
mov eax, count
call WriteHex
mov edx, OFFSET prompt2
call WriteString
mov eax, [esi]
call WriteDec
call crlf
add esi, 4
inc count
loop top
call WaitMsg
exit
main ENDP
Get_frequencies PROC USES edi esi,
pval1: DWORD,
tableVal: DWORD
mov edi, pval1 ;edi points to target array
mov esi, pval1 ;esi points to freqTable
mov edx, 0
mov eax, 0
mov numCount, 0
L1:
mov al, [edi]
mov dl, [esi]
mov temp, dl
cmp al, 0
jne L2
jmp next
L2:
inc edi
cmp al, dl
jne L1
inc numCount
jmp L1
next:
mov ecx, esi
mov ecx, tableVal
imul edx, 4
add ecx, edx
mov ebx, numCount
mov [ecx], ebx
cmp temp, 0
je finish
inc esi
inc edi
jmp L1
finish:
ret
Get_frequencies ENDP
END main
So the numCount global variable contains how many times a character is repeated and I add the number to the frequency table depending on the hex value. I try to increase the esi and edi to go again starting at the following value on the start but it gives me an exception handle error.
Thank you very much
I'm new to assembly language and I'm having trouble with some basic programming problems and I was wondering if you guys could point me in the right direction.
I'm trying to write a function that traverses through an array and sums up the values of its elements. Given given a pointer int *array and some length x.
What I've been able to do so far is write the initial data and place the initial pointer which isn't much but its a start. How would I use a loop in assembly to traverse through the array?
PUSH EBX
PUSH ECX
PUSH EDX
PUSH ESI
PUSH EDI
MOV EBX, array
MOV ECX, x
mov eax, 2;
mov ebx, array;
lea edx, [ebx+eax*4];
You do not need to save all of those registers. If your function uses esi, edi, ebx, ebp, then you must save them in the prologue and restore them in the epilogue. MASM can do that for you with the keyword uses
SomeProcedure proc uses esi, edi, ebx Val1:DWORD, Val2:DWORD
ret
SomeProcedure endp
Here is one way you can do it:
.686
.model flat, stdcall
option casemap :none
include kernel32.inc
includelib kernel32.lib
.data
Array dd 1, 2, 3, 4, 5, 6, 7, 8, 9
Array_Size equ ($ - Array) / 4
.code
start:
push Array_Size - 1
push offset Array
call SumArray
; eax contains sum of array
; print it out here.
push 0
call ExitProcess
SumArray:
push esi ; need to preserve esi
mov esi, [esp + 8] ; address of array
mov ecx, [esp + 12] ; size of array - 1
xor eax, eax ; holds sum
xor edx, edx ; index
AddIt:
add eax, [esi + edx * 4]
inc edx
dec ecx
jns AddIt ; is ecx ! neg repeat loop
pop esi
ret
end start
So we're currently studying Intel 8086 Insertion Sort Code that our professor showed us. He wanted us to figure out why the code skips the 0th element within the array and the 3rd element in the array from a code that he had taken from the web.
; void isort(int *a, int n)
; sorts the first n elements of a
;
; Parameters
; a - pointer to the array
; n - number of elements to sorts
%define a [ebp + 8]
%define n [ebp + 12]
isort:
enter 0, 0
pusha
mov ecx, 1
for:
mov ebx, ecx
imul ebx, 4
add ebx, a
mov ebx, [ebx]
mov edx, ecx
dec edx
while:
cmp edx, 0
jl while_quit
mov eax, edx
imul eax, 4
add eax, a
cmp ebx, [eax]
jge while_quit
mov esi, [eax]
mov dword [eax + 4], esi
dec edx
jmp while
while_quit:
mov [eax], ebx
inc ecx
cmp ecx, n
jl for
popa
leave
ret
And the sample array was {5, 8, 12, 2, 1, 7}. This is more for understanding the 8086 language since we just started a couple days ago, and I was wondering if anyone could explain how and what might be going wrong.
Consider what the code will do when ECX is 1:
The while loop will be entered with EBX=8 and EDX=0.
The jl while_quit will not be taken, since EDX is 0.
EBX is compared to [EAX]. That is; 8 is compared to a[0], which is 5, so the jge while_quit is taken.
mov [eax], ebx stores 8 at a[0], so your array now contains {8,8,12,2,1,7}. Clearly not what you want, since you've lost one of the original elements.
Apart from the code's logical flaw, those imul instructions are completely unnecessary since you can use scaled indices on the x86. So the sorting code can be simplified to this (I've verified that it sorts the array correctly):
mov ecx, 1
for_:
; esi = &a[holePos]
lea esi,[a + ecx*4]
; valueToInsert = a[holePos]
mov ebx, [esi]
while_:
; Did we reach the beginning of the array?
cmp esi, OFFSET a
jle while_quit
; valueToInsert < a[holePos-1] ?
cmp ebx, [esi-4]
jge while_quit
; a[holePos] = a[holePos-1]
mov eax, [esi-4]
mov [esi], eax
; esi = &a[holePos-1]
sub esi,4
jmp while_
while_quit:
; a[holePos] = valueToInsert
mov [esi], ebx
inc ecx
cmp ecx, 6
jl for_
I'm using MASM syntax, but you get the idea.
I am writing a number manipulation program, and one step is to reverse the array. So far I have
reverseArray proc
mov eax, arraySize
mov temp, eax
Imul eax, 4
mov esi, eax
mov eax, 0
mov number, 0
jne L1
L1:
cmp temp, 0
je L3
mov eax, numbers[esi]
mov tempnumbers[ecx], eax
mov eax, tempnumbers[ecx]
call writeDec
call crlf
sub esi,4
add ecx, 4
sub temp, 1
loop L1
L2:
ret
L3:
.If(number >= 0)
mov esi, 0
.ENDIF
mov eax, number
cmp eax, arraySize
je L2
mov eax, tempnumbers[esi]
mov numbers[esi], eax
add esi, 4
add number, 1
loop L3
However this only reverses about half of my array. Did I do something wrong with the esi or ecx counters? Any help would be appreciated.
Use edi instead of ecx, and set it to 0 at the start.