Problem 3 Sum of array Write a PIC18f452 datasheet assembly

Problem 3: Sum of array

Write a PIC18f452 datasheet assembly program that uses an array of signed integers of 10 elements and computes the sum of all the elements in the array.

Solution

MOV AX, @DATA ; initialize DS MOV DS, AX MOV BX, 10 ; set BX=10 LEA DX, PROMPT ; load and display the string PROMPT MOV AH, 9 INT 21H MOV CX, BX ; set CX=BX LEA SI, ARRAY ; set SI=offset address of ARRAY @LOOP: ; loop label XOR AH, AH ; clear AH MOV AL, [SI] ; set AX=[SI] CALL OUTDEC ; call the procedure OUTDEC INC SI ; set SI=SI+1 MOV AH, 2 ; set output function MOV DL, 20H ; set DL=20H INT 21H ; print a character LOOP @LOOP ; jump to label @LOOP while CX!=0 LEA DX, RESULT ; load and display the string RESULT MOV AH, 9 INT 21H LEA SI, ARRAY ; set SI=offset address of ARRAY CALL SUM ; call the procedure SUM CALL OUTDEC ; call the procedure OUTDEC MOV AH, 4CH ; return control to DOS INT 21H MAIN ENDP ;**************************************************************************; ;**************************************************************************; ;------------------------- Procedure Definitions ------------------------; ;**************************************************************************; ;**************************************************************************; ;**************************************************************************; ;--------------------------------- SUM ----------------------------------; ;**************************************************************************; SUM PROC ; this procedure will calculate the sum of an array ; input : SI=offset address of the array ; : BX=size of the array ; output : AX=sum of the array PUSH CX ; push CX onto the STACK PUSH DX ; push DX onto the STACK XOR AX, AX ; clear AX XOR DX, DX ; clear DX MOV CX, BX ; set CX=BX @SUM: ; loop label MOV DL, [SI] ; set DL=[SI] ADD AX, DX ; set AX=AX+DX INC SI ; set SI=SI+1 LOOP @SUM ; jump to label @SUM while CX!=0 POP DX ; pop a value from STACK into DX POP CX ; pop a value from STACK into CX RET ; return control to the calling procedure SUM ENDP ;**************************************************************************; ;-------------------------------- OUTDEC --------------------------------; ;**************************************************************************; OUTDEC PROC ; this procedure will display a decimal number ; input : AX ; output : none PUSH BX ; push BX onto the STACK PUSH CX ; push CX onto the STACK PUSH DX ; push DX onto the STACK CMP AX, 0 ; compare AX with 0 JGE @START ; jump to label @START if AX>=0 PUSH AX ; push AX onto the STACK MOV AH, 2 ; set output function MOV DL, \"-\" ; set DL=\'-\' INT 21H ; print the character POP AX ; pop a value from STACK into AX NEG AX ; take 2\'s complement of AX @START: ; jump label XOR CX, CX ; clear CX MOV BX, 10 ; set BX=10 @OUTPUT: ; loop label XOR DX, DX ; clear DX DIV BX ; divide AX by BX PUSH DX ; push DX onto the STACK INC CX ; increment CX OR AX, AX ; take OR of Ax with AX JNE @OUTPUT ; jump to label @OUTPUT if ZF=0 MOV AH, 2 ; set output function @DISPLAY: ; loop label POP DX ; pop a value from STACK to DX OR DL, 30H ; convert decimal to ascii code INT 21H ; print a character LOOP @DISPLAY ; jump to label @DISPLAY if CX!=0 POP DX ; pop a value from STACK into DX POP CX ; pop a value from STACK into CX POP BX ; pop a value from STACK into BX RET ; return control to the calling procedure OUTDEC ENDP ;**************************************************************************; ;--------------------------------------------------------------------------; ;**************************************************************************; END MAIN