Add comments to explain each line of the program and briefly explain the purpose

Question

Add comments to explain each line of the program and briefly explain the purpose of the program. Determine the values of the symbols ‘main’, ‘bound’, ‘ipt’, and ‘loop’.

BR             main

bound: .EQUATE 10    

ipt:      .EQUATE 0    

main: SUBSP        2, i       

DECI          ipt, s   

loop:     LDWA         ipt, s  

CPWA         bound, i

BRGE          endloop

ADDA          1, i      

STWA          ipt, s

DECO          ipt, s   

LDBA          '  ', i

STBA           charOut, d

BR               loop

endloop: ADDSP        2, i

STOP

  .END

Explanation / Answer

This assembly program just print the number from 0 to 10, separated by a space ‘ ‘.

Here is the equivalent C code

#include <stdio.h>

int bound =10 ;

int ipt;

int main(){

scanf(“%d”, &ipt);

while(ipt>=bound){

pit = ipt+1 ;

printf(“%d ”, ipt);

}

return 0;

}

BR             main //unconditional branching instruction

bound: .EQUATE 10    //global variable #2d

ipt:      .EQUATE 0    //global variable #2d

main: SUBSP        2, i       //push #bound in stack

DECI          ipt, s             // scanf(“%d”, &ipt)

loop: LDWA ipt, s //while (ipt>=bound) uses CPWA and BRGE for comparison mentioned in next two command

CPWA         bound, i

BRGE          endloop // Branch if ipt greater then or equal to bound

ADDA          1, i       //add one to ipt

STWA          ipt, s //store in ipt

DECO          ipt, s // printf(“%d ”, ipt); including next two command

LDBA          '  ', i

STBA           charOut, d // print space (‘ ‘)after ipt

BR               loop

endloop: ADDSP        2, i // pop #bound stack storage

STOP        //Stop Execution

  .END //The Sentinel for assembler

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