Write an assembly language function to count the number of odd integer values in

Question

Write an assembly language function to count the number of odd integer values in an array of integers. The assembly language routine has the definition:

int countodd( int array[], int size )

where int array[] is the array of integers to search through and int size is the number of elements in the array. The function returns an integer which is the number of odd values in the array. The first parameter, int array[], is passed by reference and is a pointer in register a1. The second, int size, is passed by value in register a2.

C Code given:
#include
#include

extern int oddcount( int array[], int size ) ;

int main( int argc, char * argv[] )
{
int intarray[] = {0, 1, 4, 7, 10, 13 } ; /* initialize array at declaration */
int size = sizeof(intarray)/sizeof(int) ; /* automagically determine number of elements in array */
int result ;

result = oddcount( intarray, size ) ;
printf( "Result for oddcount1: %d ", result ) ;

exit(0) ;

}

Explanation / Answer

START:       

XOR DX,DX ;Clear the contents of DX register

MOV AX,@DATA ;Initialize data segment

MOV DS,AX

MOV CL,COUNT ;Move count to CL register

MOV SI,OFFSET LIST ;Offset of array is moved to SI

LOOP1: MOV AX,[SI] ;The contents of array pointed by SI are moved to AX

ROR AX,01 ;After ROR, the LSB specifies if the no is even/odd

JC ODD ;Jump on no carry to ODD

JMP NEXT ; Jump to next

ODD: INC DX ; Increment DX register

NEXT: ADD SI,02 ;Increment SI by 2

DEC CL ; Decrement CL by 1

JNZ LOOP1 ; Jump to loop1 if ZF! = 0

INT 03H

END START

Output DX register gives number of odd numbers in array

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