*
*``````````````````````````````*
* MUL8 :: 8BIT MULTIPLY (16BR) *
*-                            -*
* MULTIPLY TWO 8BIT NUMBERS TO *
* GET  16BIT RESULT. NUMBERS   *
* MUST BE UNSIGNED.            *
*                              *
* ORIGINAL AUTHOR IS WHITE     *
* FLAME, AS SHARED ON          *
* CODEBASE64. I HAVE MADE SOME *
* MINOR ALTERATIONS, BUT NOT   *
* NEARLY ENOUGH TO CALL IT MY  *
* OWN.                         *
*-                            -*
* CLOBBERS:                    *
*                              *
* FLAGS:  ????----  REG: AXYM  *
*-                            -*
* CYCLES: ???                  *
* SIZE:                        *
*-                            -*
* USAGE:                       *
*                              *
*        LDA  #100             *
*        PHA                   *
*        PDA #200              *
*        PHA                   *
*        JSR MUL8              *
*-                            -*
* ENTRY                        *
*                              *
* LOW BYTE OF RETURN ADDRESS   *
* HIGH BYTE OF RETURN ADDRESS  *
* SECOND NUM TO BE MULTIPLIED  *
* FIRST NUM TO BE MULTIPLIED   *
*-                            -*
* EXIT                         *
*                              *
*   Y = HIGH BYTE OF PRODUCT   *
*   X = LOW BYTE OF PRODUCT    *
*   A = LOW BYTE OF PRODUCT    *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
MUL8
*
** GET RETURN ADDRESS
*
         PLA
         STA   :RETADR
         PLA
         STA   :RETADR+1
*
** GET PARAMETERS
*
         PLA
         STA   :MUL1
         PLA
         STA   :MUL2
*
** INIT
*
         LDA   #$00
         TAX
         STX   :MUL1H
         BEQ   :GOLOOP
*
:DOADD
         CLC
         ADC   :MUL1
         TAY
*
         TXA
         ADC   :MUL1H
         TAX
         TYA
*
:LP
         ASL   :MUL1
         ROL   :MUL1H
:GOLOOP
         LSR   :MUL2
         BCS   :DOADD
         BNE   :LP
*
** RESTORE RETURN ADDRESS
*
         LDA   :RETADR+1
         PHA
         LDA   :RETADR
         PHA
*
         RTS
*
** DATA
*
:MUL1    DS    1
:MUL2    DS    1
:RETADR  DS    2
:MUL1H   DS    1