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!