Data commit

Task/Function-definition/6502-Assembly/function-definition-1.6502

@@ -0,0 +1,8 @@
+MULTIPLY: STX   MULN      ; 6502 has no "acc += xreg" instruction,
+          TXA             ; so use a memory address
+MULLOOP:  DEY
+          CLC             ; remember to clear the carry flag before
+          ADC   MULN      ; doing addition or subtraction
+          CPY   #$01
+          BNE   MULLOOP
+          RTS

Task/Function-definition/6502-Assembly/function-definition-2.6502

@@ -0,0 +1,22 @@
+; https://skilldrick.github.io/easy6502/
+; Multiplies A by X
+
+define    memory  1040
+
+          JMP MAIN
+
+MULTIPLY: STA memory   ; memory = A
+          BEQ MUL_END  ; A = 0
+          TXA          ; A = X
+          BEQ MUL_END  ; X = 0 -> A = 0
+          LDA memory
+          CLC
+MUL_LOOP: DEX          ; X -= 1
+          BEQ MUL_END  ; X = 0 -> A = A * X
+          ADC memory   ; A += memory
+          JMP MUL_LOOP
+MUL_END:  RTS
+
+MAIN:     LDA #50
+          LDX #5
+          JSR MULTIPLY