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c64: fixed issue #203, added openroms-compatible cc65 library overrides for _cgetc and PLOT
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Steven Hugg committed
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@@ -28,8 +28,6 @@ export class C64_WASMMachine extends BaseWASMMachine
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lightpen_y = 0;
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loadBIOS(srcArray: Uint8Array) {
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var patch1ofs = 0xea24 - 0xe000 + 0x3000;
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if (srcArray[patch1ofs] == 0xc4) srcArray[patch1ofs] = 0x60; // cursor move, KIL -> RTS
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super.loadBIOS(srcArray);
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}
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reset() {
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@@ -79,6 +77,11 @@ export class C64_WASMMachine extends BaseWASMMachine
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for (var i=0; i<100000 && this.getPC() != this.prgstart; i++) {
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this.exports.machine_tick(this.sys);
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}
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// release RETURN key
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// (otherwise it stays stuck down and every keyboard read returns CR,
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// e.g. conio cgetc() always returning a bogus char - GH issue #203)
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this.exports.machine_key_up(this.sys, 13);
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this.exports.machine_exec(this.sys, 1); // chips/kbd.c has a "sticky counter"
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} else {
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// get out of reset
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this.exports.machine_exec(this.sys, 100);
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@@ -0,0 +1,13 @@
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# Rebuild the Open ROMs compatibility object for cc65 on C64.
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#
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# openroms-compat.o - linked before c64.lib (see src/worker/platforms.ts,
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# libargs for the 'c64' platform) so it overrides
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# cc65 runtime routines that depend on KERNAL entry
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# points not implemented by the Open ROMs BIOS:
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# _cgetc (KBDREAD $E5B4)
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# PLOT ($FFF0 / UPDCRAMPTR $EA24)
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all: openroms-compat.o
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openroms-compat.o: openroms-compat.s
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ca65 -I /Users/sehugg/8bitworkshop-compilers/cc65/asminc openroms-compat.s
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Binary file not shown.
@@ -0,0 +1,123 @@
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;
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; Open ROMs compatibility overrides for the cc65 runtime library.
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;
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; The Open ROMs KERNAL used by 8bitworkshop is not binary-compatible
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; with the original Commodore KERNAL at some undocumented entry points
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; that cc65 routines call directly. This object is linked before
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; c64.lib so ld65 resolves the overridden symbols here and never pulls
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; the incompatible library members (cgetc.o, kplot.o).
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;
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; Only entry points that are actually broken in Open ROMs are
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; overridden; everything else (CLRSCR $E544, SCREEN $FFED, BSOUT,
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; etc.) works and is left to the KERNAL.
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;
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; Safe to use with the original C64 KERNAL as well: _cgetc only
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; depends on the documented keyboard buffer interface (KEY_COUNT /
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; KEY_BUF), and PLOT is a pure RAM-pointer implementation.
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;
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.export _cgetc
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.export PLOT
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.include "c64.inc"
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KEY_BUF := $0277 ; keyboard buffer (10 bytes, FIFO)
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; ----------------------------------------------------------------------------
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; char cgetc (void)
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;
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; cc65's stock version jumps to KBDREAD ($E5B4), which is "get character from
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; keyboard buffer" on the original KERNAL but unimplemented VIC-II init code
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; inside Open ROMs - so cgetc() returned garbage instead of blocking/reading.
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; Read the buffer directly instead (same thing the stock KERNAL GETIN path does).
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;
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_cgetc:
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lda KEY_COUNT
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beq _cgetc ; wait until a character is available
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sei ; IRQ must not touch the buffer while we shift
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lda KEY_BUF ; first character (to be returned)
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pha
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ldx #$00
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L: lda KEY_BUF+1,x ; shift remaining characters down
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sta KEY_BUF,x
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inx
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cpx #$09 ; buffer holds 10 characters
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bne L
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dec KEY_COUNT
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cli
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pla
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ldx #$00 ; cc65 char return: char in A, high byte in X
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rts
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; ----------------------------------------------------------------------------
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; PLOT - set/read cursor position (replaces kplot.o)
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;
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; cc65's kplot.o calls the original ROM PLOT ($FFF0) and UPDCRAMPTR ($EA24)
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; directly. In Open ROMs, that path runs into unimplemented code ($EA24 is a
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; KIL instruction), and the previous workaround (patching $EA24 to RTS in the
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; BIOS) left CRAM_PTR stale, breaking text colors. This replacement computes
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; SCREEN_PTR/CRAM_PTR directly - no KERNAL calls at all.
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;
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; Entry: C=0: set position (X = row, Y = column), like the KERNAL routine.
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; C=1: read position (returns X = row, Y = column, C = 0).
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;
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ZP_ROW := $FB ; temp: 16-bit offset (row*40 + col)
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ZP_ROWHI := $FC
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ZP_ROW8 := $FD ; temp: row*8
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ZP_ROW8HI := $FE
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.proc PLOT
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bcs @read
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; offset = row*40 + column
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stx ZP_ROW
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lda #$00
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sta ZP_ROWHI
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asl ZP_ROW
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rol ZP_ROWHI ; *2
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asl ZP_ROW
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rol ZP_ROWHI ; *4
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asl ZP_ROW
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rol ZP_ROWHI ; *8
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lda ZP_ROW
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sta ZP_ROW8
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lda ZP_ROWHI
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sta ZP_ROW8HI ; ZP_ROW8/HI = row*8
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asl ZP_ROW
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rol ZP_ROWHI ; *16
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asl ZP_ROW
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rol ZP_ROWHI ; *32
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lda ZP_ROW
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clc
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adc ZP_ROW8
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sta ZP_ROW ; + row*8 = row*40
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lda ZP_ROWHI
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adc ZP_ROW8HI
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sta ZP_ROWHI
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; NOTE: no column offset here - the KERNAL PLOT convention is that
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; SCREEN_PTR/CRAM_PTR point to the START of the cursor row; the
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; column is applied by callers via indexed addressing
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; (e.g. putchar: sta (SCREEN_PTR),y with Y = CURS_X).
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; SCREEN_PTR = $0400 + row*40
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lda #<$0400
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clc
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adc ZP_ROW
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sta SCREEN_PTR
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lda #>$0400
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adc ZP_ROWHI
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sta SCREEN_PTR+1
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; CRAM_PTR = $D800 + offset
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lda #<$D800
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clc
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adc ZP_ROW
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sta CRAM_PTR
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lda #>$D800
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adc ZP_ROWHI
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sta CRAM_PTR+1
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rts
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@read: ldx CURS_Y
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ldy CURS_X
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clc
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rts
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.endproc
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@@ -285,7 +285,8 @@ export var PLATFORM_PARAMS = {
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arch: '6502',
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define: ['__CBM__', '__C64__'],
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cfgfile: 'c64.cfg', // SYS 2061
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libargs: ['c64.lib'],
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libargs: ['openroms-compat.o', 'c64.lib'],
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extra_link_files: ['openroms-compat.o'],
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acmeargs: ['-f', 'cbm'],
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//extra_link_files: ['c64-cart.cfg'],
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},
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@@ -318,7 +318,7 @@ describe('Worker', function() {
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it('should compile C64 cc65 skeleton', function(done) {
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var csource = ab2str(fs.readFileSync('presets/c64/skeleton.cc65'));
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csource = csource.replace('#include "','//');
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compile('cc65', csource, 'c64.wasm', done, 3001, 3, 0);
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compile('cc65', csource, 'c64.wasm', done, 3112, 3, 0);
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});
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it('should compile zmachine inform6 skeleton', function(done) {
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var csource = ab2str(fs.readFileSync('presets/zmachine/skeleton.inform6'));
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