Write an ARM assembly function that takes an array of integers and insures that all entries are positive. Remember the initial integer in the array is at index zero.

The C language program is:

/* absdriver.c - driver for absarray function */

#include

#include

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

int main( int argc, char * argv[] )

{

         int array[] = {1, 3, -5, -252, 280, -332 } ;

            int asize = sizeof(array) / sizeof(int) ;

            int result ;

            int i ;

            result = absarray( array, asize ) ;

            for( i = 0 ; i < asize ; i++ )

                        printf( " %d ", array[i] ) ;

            printf( "\n" ) ;

            exit( 0 ) ;

}

The input to the ARM assembly language function is a pointer to the first element of the array in register a1. The size of the array is in a2 and is the number of integers. Remember an integer is 4 bytes long.

Recall that the ldr instruction does not affect the condition codes. Also consider the reverse subtract instruction, rsb.