"Custom" Read_Btns for all buttons doing the same thing.

[limitzer0]

I plan on using all of the buttons on controller 1 to do the same thing. I initially used Read_Btns and just checked register A was not 0. I went to go back and use Vec_Btn_State but do not really see a reason to. Looking into it further it looks like I can save a few cycles by removing the LF1EA loop in Read_Btns. After the return from Read_Btns_2 I just look for register A being >00 and <=08 to count as a button push. Does anyone see anything wrong with this method? It seems simple and it all works fine but I've gotten little sleep and can't think straight at this point. Let me know if you all think there is a reason not to do it this way.


Read_Btns_2:   LDX     #Vec_Button_1_1 ;Point to button flags

LDA     -3,X            ;Save previous state

               STA     -2,X

               LDA     #$0E            ;Sound chip register 0E to port A

               STA     <VIA_port_a

               LDD     #$1901          ;sound BDIR on, BC1 on, mux off

               STA     <VIA_port_b

               NOP                     ;pause

               STB     <VIA_port_b     ;sound BDIR off, BC1 off, mux off

               CLR     <VIA_DDR_a      ;DDR A to input

               LDD     #$0901          ;sound BDIR off, BC1 on, mux off

               STA     <VIA_port_b

               NOP                     ;pause

               LDA     <VIA_port_a     ;Read buttons

               COMA                    ;Convert to active high

               STA     -3,X            ;Save buttons

               STB     <VIA_port_b     ;sound BDIR off, BC1 off, mux off

               LDB     #$FF

               STB     <VIA_DDR_a      ;DDR A to output

               COMA                    ;Check for transitions

               ORA     -2,X

               COMA

               STA     -1,X            ;Store transition result

;               PSHS    A               ;Save result for return value

;               LDB     #$01            ;Initialize bit position


;LF1EA2      TFR     B,A             ;Mask out bit

;               ANDA    ,S

;               STA     ,X+             ;Store masked bit

;               ASLB                    ;Go back for next bit

;               BNE LF1EA2

;               PULS    A,PC            ;Get back transition bits and return

 RTS


[Malban]

If you don't use any stored results (Vec_Button_1_1...) - sure can do.

You can finish even earlier depending on what results you need...
Transition check is probably also not needed.

And if you do not store anything... you need not set up "X" either, so the first 3 lines are also doing "nothing" for you


But saving cycles on a function you use once a round... is not saving really "much" :-)...

[limitzer0]

Yeah. Not much but minimal effort so I might as well.

In addition to the other stuff I removed I ended up removing "STA -1,X ;Store transition result". It seems I need the rest for debounce. EDIT: Not debounce I suppose but I want to have to release the button and press it again instead of holding it down to register as a new button push.

Thanks. I never feel comfortable messing with BIOS functions.