Function calls and indirect addressing

Function calls and indirect addressing/152120201044.asm

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+    LIST 	P=16F877A
+    INCLUDE	P16F877.INC
+    __CONFIG _CP_OFF &_WDT_OFF & _BODEN_ON & _PWRTE_ON & _XT_OSC & _WRT_ENABLE_OFF & _LVP_OFF & _DEBUG_OFF & _CPD_OFF
+    radix	dec
+
+    ; Reset vector
+    org 0x00
+    ; ---------- Initialization ---------------------------------
+    BSF     STATUS, RP0	; Select Bank1
+    CLRF    TRISB	; Set all pins of PORTB as output
+    CLRF    TRISD	; Set all pins of PORTD as output
+    BCF     STATUS, RP0	; Select Bank0    
+    CLRF    PORTB	; Turn off all LEDs connected to PORTB
+    CLRF    PORTD	; Turn off all LEDs connected to PORTD
+    
+    ; ---------- Your code starts here --------------------------
+    
+    x	    EQU	    0x20
+    y	    EQU	    0X21
+    N	    EQU	    0X22
+    sum	    EQU	    0X23
+    R_L	    EQU	    0x24	; Low byte of the result
+    R_H	    EQU	    0x25	; High byte of the result. R = X * Y
+    temp    EQU     0x26
+    count   EQU     0x27
+    Rem     EQU     0x28
+    Q       EQU     0x29
+    A	    EQU	    0x32  
+	
+    MOVLW   A
+    MOVWF   FSR ; FSR = &A[0]
+    
+    
+main:
+    
+    MOVLW   112
+    MOVWF   x
+    MOVLW   100
+    MOVWF   y
+    MOVLW   125
+    MOVWF   N
+    
+    
+    CALL GenerateNumbers
+    CALL AddNumbers
+    CALL DisplayNumbers
+    GOTO finish
+    
+    ;x*y
+Multiply:
+    COUNT   EQU	    0x70	
+    CLRF    COUNT	; COUNT = 0
+    BSF	    COUNT, 3	; COUNT = 8  
+    CLRF    R_H		; R_H = 0
+    MOVFW   y		; WREG = y (Multiplier)
+    MOVWF   R_L		; R_L = WREG
+    MOVFW   x		; WREG = x (Multiplicant)
+    RRF	    R_L, F	; R_L = R_L >> 1
+Mult8x8_Loop:
+    BTFSC   STATUS, C	; Is the least significant bit of Y equal to 1?
+    ADDWF   R_H, F	; R_H = R_H + WREG
+    RRF	    R_H, F	; R_H = R_H >> 1
+    RRF	    R_L, F	; R_L = R_L >> 1
+    
+    DECFSZ  COUNT	; COUNT = COUNT-1       
+    GOTO    Mult8x8_Loop
+    RETURN		; DONE
+
+    ;temp/3
+Division:
+    Counter	    EQU	    0x71    
+    MOVLW   8
+    MOVWF   Counter
+    CLRF    Rem
+    MOVF    temp, W
+    MOVWF   Q
+process:
+    BCF	    STATUS, C		
+    RLF	    Q, F
+    RLF	    Rem, F
+    MOVLW   3
+    SUBWF   Rem, W
+    BTFSS   STATUS, C
+    GOTO    countdown
+    BSF	    Q, 0
+    MOVWF   Rem
+countdown:
+    DECFSZ  Counter, F
+    GOTO    process
+    RETURN
+    
+    
+GenerateNumbers:
+    ;y<N
+    MOVF	N, W		    ; WREG = N
+    SUBWF	y, W		    ; WREG = y - WREG
+    BTFSC	STATUS, C	    ; If y<N, then C must be NOT set
+    GOTO	x_small_N
+    GOTO        true
+    ;x<N
+x_small_N:
+    MOVF	N, W		    ; WREG = N
+    SUBWF	x, W		    ; WREG = x - WREG
+    BTFSC	STATUS, C	    ; If x<N, then C must be NOT set
+    GOTO	generate_end
+    GOTO        true
+true:
+    ;(x + y) % 2
+    MOVF    x, W
+    ADDWF   y, W
+    MOVWF   temp
+    BTFSC   temp, 0
+    GOTO    true_if
+    ;else
+    MOVF    x, W
+    ADDWF   y, W
+    MOVWF   temp
+    MOVWF   temp
+    CALL    Division
+    INCF    count, F   ; count++
+    
+    ; A[count] = Q
+    MOVF    Q, W
+    MOVWF   INDF
+    INCF    FSR, F
+    
+    ; y = y + 3
+    INCF    y, F
+    INCF    y, F
+    INCF    y, F
+    GOTO    GenerateNumbers
+ 
+true_if:
+    CALL    Multiply
+    INCF    count, F    ; count++
+    
+    ; A[count] = R_L + R_H
+    MOVF    R_L, W
+    ADDWF   R_L, W  ;2*p0
+    ADDWF   R_H, W
+    MOVWF   temp
+    MOVF    temp, W
+    MOVWF   INDF
+    INCF    FSR, F
+    
+    ; x = x + 1
+    INCF    x, F
+    GOTO    GenerateNumbers
+    
+generate_end: 
+    RETURN
+    
+AddNumbers:
+    MOVLW   0
+    MOVWF   sum
+    
+    i	    EQU		0x72
+    MOVLW   A
+    MOVWF   FSR
+    CLRF    i
+loop:
+    MOVF    count, W
+    SUBWF   i, W
+    BTFSC   STATUS, C
+    GOTO    loop_end
+    ;sum += A[i] 
+    MOVF    INDF, W
+    INCF    FSR, F
+    ADDWF   sum, F
+    ;i++
+    INCF    i, F
+    GOTO    loop
+loop_end:
+    RETURN
+    
+    
+DisplayNumbers:
+    BANKSEL	 TRISD
+    CLRF	 TRISD
+    MOVLW	 0xFF
+    MOVWF	 TRISB
+    BANKSEL	 PORTD
+    
+delayMiliSecond EQU 0x30
+currentDelayMicroSecond EQU 0x31
+ 
+    m EQU 0x73
+    MOVLW d'5'
+    MOVWF m
+ 
+   
+    MOVLW A
+    MOVWF FSR
+    MOVF sum, W
+    MOVWF PORTD
+    GOTO delay_250
+
+for:
+    MOVF INDF, W
+    MOVWF PORTD
+    INCF FSR, F
+    ; FSR < 5
+    DECFSZ m, F
+    GOTO delay_250
+    RETURN
+
+delay_250:
+    NOP
+    DECFSZ delayMiliSecond, F
+    GOTO delay_begin
+    GOTO button_3
+
+delay_begin:
+    MOVLW d'250'
+    MOVWF currentDelayMicroSecond
+    GOTO delay_body
+
+delay_body:
+    NOP
+    DECFSZ currentDelayMicroSecond, F
+    GOTO delay_body
+    GOTO delay_250
+
+button_3:
+    BTFSC PORTB, 3
+    GOTO button_3
+    GOTO for
+
+    
+    
+finish:
+    
+    ; ---------- Your code ends here ----------------------------    
+    MOVWF   PORTD    	; Send the result stored in WREG to PORTD to display it on the LEDs
+    
+LOOP    GOTO    $	; Infinite loop
+    END
+
+
+