* *``````````````````````````````* * DIVD8 :: 8BIT DIVISION (8BR) * *- -* * DIVIDE ONE 8BIT NUMBER BY * * ANOTHER TO GET AN 8BIT * * RESULT. UNSIGNED ONLY. * * * * ORIGINAL AUTHOR IS WHITE * * FLAME, AS SHARED ON * * CODEBASE64. MINOR CHANGES. * *- -* * CLOBBERS: * * * * FLAGS: ????---- REG: AXYM * *- -* * CYCLES: ??? * * SIZE: * *- -* * USAGE: * * * * LDA #200 * * PHA * * PDA #10 * * PHA * * JSR DIV8 * *- -* * ENTRY * * * * LOW BYTE OF RETURN ADDRESS * * HIGH BYTE OF RETURN ADDRESS * * SECOND NUM TO BE MULTIPLIED * * FIRST NUM TO BE MULTIPLIED * *- -* * EXIT * * * * .Y = REMAINDER * * .X = UNCHANGED * * .A = QUOTIENT * * * * [RETURN] = QUOTIENT * * [RETLEN] = 1 (QUOT LENGTH) * *,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,* * DIVD8 * ** GET RETURN ADDRESS * PLA STA RETADR PLA STA RETADR+1 * ** GET PARAMETERS * PLA STA :DVEND PLA STA :DVSOR * LDA #$00 LDY #8 ASL :DVSOR :L1 ROL CMP :DVEND BCC :L2 SBC :DVEND :L2 ROL :DVSOR DEY BNE :L1 STA :REM * ** RESTORE RETURN ADDRESS * LDA RETADR+1 PHA LDA RETADR PHA * ** LOAD QUOTIENT INTO A, REMAINDER INTO X * LDY :REM ; REMAINDER TO Y LDA #1 STA RETLEN LDA :DVSOR STA RETURN * RTS * ** DATA * :REM DS 1 :DVEND DS 1 :DVSOR DS 1 *