Subversion Repositories copyblaze

; this programm calculate the sum of the "value" 16bit.
; value = 5; total = 5 + 3 + 2 + 1 = 15
; the result is 16bit outputed 
                waveform_port           .EQU    0x02
                counter_port            .EQU    0x04
        
                total_low       .EQU   s0
                total_high      .EQU   s1
                value           .EQU   s8
                ;
start:
                LOAD    value,          0x1F    ; find sum of all values to 1F
                LOAD    total_low,      0x00    ; clear 16-bit total
                LOAD    total_high,     0x00
                
                CALL    sum_to_value            ; calculate sum of all numbers up to value
                
                OUTPUT  total_high,     counter_port    ; Result will be 496 (1F0 hex)
                OUTPUT  total_low,      waveform_port 

end:            
                JUMP    end
                ;
                
                ; Subroutine called recursively
sum_to_value:
                ADD             total_low,      value   ; perform 16-bit addition
                ADDCY   total_high,     00
                SUB             value,          01              ; reduce value by 1
                RETURN  Z                                       ; finished if down to zero
                CALL    sum_to_value            ; recursively call of subroutine
                RETURN                                          ; definitively finished!