        !to "keycomp.prg",cbm

        zpBuffer = $fa  ; $fa-$fb are reserved for 2 bytes of key buffer

        * = $0801
        !byte $0c, $08, $00, $00, $9e, $32, $30, $36, $31, $00, $00, $00

        * = $080d

        ; key buffer initialization
        ldx #$f0        ; initialize key buffer
        stx zpBuffer    ; with two different
        inx             ; values to avoid instant
        stx zpBuffer+1  ; match at the beginning

        ; border color initialization
        lda #$00        ; set startup border color to black
        sta $d020       ; which means "no match"

        ; main loop
mainloop
        lda zpBuffer    ; shift key buffer
        sta zpBuffer+1  ; by one
readKey
        jsr $ffe4       ; read key
        beq readKey     ; if no key pressed loop forever
        jsr $ffd2       ; show key on the screen
        sta zpBuffer    ; store the key to key buffer

        lda zpBuffer    ; compare the last stored key
        cmp zpBuffer+1  ; with the old key value
        beq cmpMatch    ; if there is a match jmp to cmpMatch

        lda #$00        ; if two pressed keys are different
        sta $d020       ; change border color to black

        jmp cmpOut      ; skip the other condition code block
cmpMatch
        lda #$02        ; if there is a repeated key
        sta $d020       ; change border color to red
cmpOut
        jmp mainloop    ; wait for the next key

I prepared an example to you just like you've wanted. If you press same keys in a row twice, border color changes to red, otherwise stays black.

Warning! This example uses kernal routines. There is nothing wrong with that. But there is also a lower level way to do this without using $ffd2 (Output Vector, chrout) and $ffe4 (Get From Keyboad) kernal calls. But since it is much more complicated to understand, I prefered this example.

If you want to know what is happening behind the scenes (kernal calls), you can easily trace the kernal ROM codes from AAY64 documentation. Here is the links:

Main AAY Page: http://www.the-dreams.de/aay.html

AAY64 Online HTML Version: http://unusedino.de/ec64/technical/aay/c64/

Kernal ROM Listing: http://unusedino.de/ec64/technical/aay/c64/krnromma.htm

$ffd2 (Output Vector, chrout): http://unusedino.de/ec64/technical/aay/c64/romffd2.htm

$ffe4 (Get From Keyboad): http://unusedino.de/ec64/technical/aay/c64/romffe4.htm

You can browse deeper by pressing links on the opcodes and addresses.

Here goes the example code. You can compile this code using ACME Crossassembler which you can find here -> http://www.esw-heim.tu-clausthal.de/~marco/smorbrod/acme/

        !to "keycomp.prg",cbm

        zpBuffer = $fa  ; $fa-$fb are reserved for 2 bytes of key buffer

        * = $0801
        !byte $0c, $08, $00, $00, $9e, $32, $30, $36, $31, $00, $00, $00

        * = $080d

        ; key buffer initialization
        ldx #$f0        ; initialize key buffer
        stx zpBuffer    ; with two different
        inx             ; values to avoid instant
        stx zpBuffer+1  ; match at the beginning

        ; border color initialization
        lda #$00        ; set startup border color to black
        sta $d020       ; which means "no match"

        ; main loop
mainloop
        lda zpBuffer    ; shift key buffer
        sta zpBuffer+1  ; by one
readKey
        jsr $ffe4       ; read key
        beq readKey     ; if no key pressed loop forever
        jsr $ffd2       ; show key on the screen
        sta zpBuffer    ; store the key to key buffer

        lda zpBuffer    ; compare the last stored key
        cmp zpBuffer+1  ; with the old key value
        beq cmpMatch    ; if there is a match jmp to cmpMatch

        lda #$00        ; if two pressed keys are different
        sta $d020       ; change border color to black

        jmp cmpOut      ; skip the other condition code block
cmpMatch
        lda #$02        ; if there is a repeated key
        sta $d020       ; change border color to red
cmpOut
        jmp mainloop    ; wait for the next key

回复收藏 0 原文

不喜欢何必死缠烂打 2024-12-20 03:49:11

我不是 C64 人，但我知道 6502 汇编。为了实现你的目标，你需要知道两件事。首先是学习 6502 汇编语言（如果您还不了解它）。例如，此页面拥有优秀的资源。

二是了解C64架构和OS。用 Commodore 的话说，它被称为Kernal，快速谷歌应该会为您指明正确的方向。

但还有一个替代方案。您始终可以使用 cc65，这是一个出色的免费软件包，由几乎符合 ISO 的 C 编译器、6502 汇编器组成、一个链接器和几个其他 6502 相关工具。它支持所有流行的 6502 平台，包括 Atari 8 位、Apple II，当然还有 Commodore 64。它有大量文档，并且邮件列表中的人员都非常友善且乐于助人。作为提示，键盘输入和屏幕输出函数在 conio.h 中定义。