c64: patched bios to fix gotoxy() problem ($EA24 KIL -> RTS)

doc/notes.txt

@@ -193,6 +193,10 @@ TODO:
   - probably XMLHttpRequest.timeout (https://github.com/getsentry/sentry-javascript/issues/2210)
 - C64
   - debugging at reset
+  - gotoxy goes to $EA24 (KIL) from PLOT (kplot.s) missing UPDCRAMPTR
+  - emu doesn't reset properly (after gotoxy() BIOS call)
+  - disk image support
+  - https://github.com/cc65/cc65/issues/946
 
 
 WEB WORKER FORMAT

presets/c64/siegegame.c

@@ -0,0 +1,239 @@
+
+#include <stdlib.h>
+#include <string.h>
+#include <joystick.h>
+#include <conio.h>
+#include <c64.h>
+#include <cbm_petscii_charmap.h>
+#include <peekpoke.h>
+
+#define COLS 40
+#define ROWS 24
+
+typedef unsigned char byte;
+typedef signed char sbyte;
+typedef unsigned short word;
+
+// BASL = text address of cursor position
+static byte** BASL = (byte**) 0xD1;
+
+byte getchar(byte x, byte y) {
+  // JSR VTABZ
+  // LDA (BASL) ($28)
+  gotoxy(x,y);		// set cursor position
+  return (*BASL)[x];	// lookup value @ cursor address
+}
+
+void delay(byte count) {
+  while (count--) {
+    word i;
+    for (i=0; i<200; i++) ;
+  }
+}
+
+////////// GAME DATA
+
+typedef struct {
+  byte x;
+  byte y;
+  byte dir;
+  word score;
+  char head_attr;
+  char tail_attr;
+  int collided:1;
+  int human:1;
+} Player;
+
+Player players[2];
+
+byte credits = 0;
+byte frames_per_move;
+byte gameover;
+
+#define START_SPEED 12
+#define MAX_SPEED 5
+#define MAX_SCORE 7
+
+///////////
+
+const char BOX_CHARS[8] = { '+', '+', '+', '+',
+                            '-', '-', '!', '!'};
+
+void draw_box(byte x, byte y, byte x2, byte y2, const char* chars) {
+  byte x1 = x;
+  cputcxy(x, y, chars[2]);
+  cputcxy(x2, y, chars[3]);
+  cputcxy(x, y2, chars[0]);
+  cputcxy(x2, y2, chars[1]);
+  while (++x < x2) {
+    cputcxy(x, y, chars[5]);
+    cputcxy(x, y2, chars[4]);
+  }
+  while (++y < y2) {
+    cputcxy(x1, y, chars[6]);
+    cputcxy(x2, y, chars[7]);
+  }
+}
+
+void draw_playfield() {
+  draw_box(0,1,COLS-1,ROWS-1,BOX_CHARS);
+  cputsxy( 0, 0, "Plyr1:");
+  cputsxy(20, 0, "Plyr2:");
+  cputcxy( 7, 0, players[0].score+'0');
+  cputcxy(27, 0, players[1].score+'0');
+}
+
+typedef enum { D_RIGHT, D_DOWN, D_LEFT, D_UP } dir_t;
+const sbyte DIR_X[4] = { 1, 0, -1, 0 };
+const sbyte DIR_Y[4] = { 0, 1, 0, -1 };
+
+void init_game() {
+  memset(players, 0, sizeof(players));
+  players[0].head_attr = '1';
+  players[1].head_attr = '2';
+  players[0].tail_attr = '#';
+  players[1].tail_attr = '*';
+  frames_per_move = START_SPEED;
+}
+
+void reset_players() {
+  players[0].x = players[0].y = 5;
+  players[0].dir = D_RIGHT;
+  players[1].x = COLS-6;
+  players[1].y = ROWS-6;
+  players[1].dir = D_LEFT;
+  players[0].collided = players[1].collided = 0;
+}
+
+void draw_player(Player* p) {
+  cputcxy(p->x, p->y, p->head_attr);
+}
+
+void move_player(Player* p) {
+  cputcxy(p->x, p->y, p->tail_attr);
+  p->x += DIR_X[p->dir];
+  p->y += DIR_Y[p->dir];
+  if ((getchar(p->x, p->y) & 0x7f) != ' ')
+    p->collided = 1;
+  draw_player(p);
+}
+
+void human_control(Player* p) {
+  byte dir = 0xff;
+  char joy;
+  if (!p->human) return;
+  if (!kbhit()) return;
+  joy = joy_read(0);
+  if (JOY_UP(joy)) dir = D_UP;
+  if (JOY_LEFT(joy)) dir = D_LEFT;
+  if (JOY_RIGHT(joy)) dir = D_RIGHT;
+  if (JOY_DOWN(joy)) dir = D_DOWN;
+  // don't let the player reverse direction
+  if (dir < 0x80 && dir != (p->dir ^ 2)) {
+    p->dir = dir;
+  }
+}
+
+byte ai_try_dir(Player* p, dir_t dir, byte shift) {
+  byte x,y;
+  dir &= 3;
+  x = p->x + (DIR_X[dir] << shift);
+  y = p->y + (DIR_Y[dir] << shift);
+  if (x < COLS && y < ROWS && (getchar(x, y) & 0x7f) == ' ') {
+    p->dir = dir;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+void ai_control(Player* p) {
+  dir_t dir;
+  if (p->human) return;
+  dir = p->dir;
+  if (!ai_try_dir(p, dir, 0)) {
+    ai_try_dir(p, dir+1, 0);
+    ai_try_dir(p, dir-1, 0);
+  } else {
+    ai_try_dir(p, dir-1, 0) && ai_try_dir(p, dir-1, 1+(rand() & 3));
+    ai_try_dir(p, dir+1, 0) && ai_try_dir(p, dir+1, 1+(rand() & 3));
+    ai_try_dir(p, dir, rand() & 3);
+  }
+}
+
+void flash_colliders() {
+  byte i;
+  // flash players that collided
+  for (i=0; i<56; i++) {
+    delay(2);
+    revers(players[0].collided && (i&1));
+    draw_player(&players[0]);
+    revers(players[1].collided && (i&1));
+    draw_player(&players[1]);
+  }
+  revers(0);
+}
+
+void make_move() {
+  byte i;
+  for (i=0; i<frames_per_move; i++) {
+    human_control(&players[0]);
+    delay(1);
+  }
+  ai_control(&players[0]);
+  ai_control(&players[1]);
+  // if players collide, 2nd player gets the point
+  move_player(&players[1]);
+  move_player(&players[0]);
+}
+
+void declare_winner(byte winner) {
+  byte i;
+  clrscr();
+  for (i=0; i<ROWS/2-3; i++) {
+    draw_box(i,i,COLS-1-i,ROWS-1-i,BOX_CHARS);
+    delay(1);
+  }
+  cputsxy(12,10,"WINNER:");
+  cputsxy(12,13,"PLAYER ");
+  cputcxy(12+7, 13, '1'+winner);
+  delay(200);
+  gameover = 1;
+}
+
+void play_round() {
+  reset_players();
+  clrscr();
+  draw_playfield();
+  while (1) {
+    make_move();
+    if (players[0].collided || players[1].collided) break;
+  }
+  flash_colliders();
+  // add scores to players that didn't collide
+  if (players[0].collided) players[1].score++;
+  if (players[1].collided) players[0].score++;
+  // increase speed
+  if (frames_per_move > MAX_SPEED) frames_per_move--;
+  // game over?
+  if (players[0].score != players[1].score) {
+    if (players[0].score >= MAX_SCORE)
+      declare_winner(0);
+    else if (players[1].score >= MAX_SCORE)
+      declare_winner(1);
+  }
+}
+
+void play_game() {
+  gameover = 0;
+  init_game();
+  players[0].human = 1;
+  while (!gameover) {
+    play_round();
+  }
+}
+
+void main() {
+  joy_install (joy_static_stddrv);
+  play_game();
+}

src/platform/c64.ts

@@ -10,6 +10,7 @@ const C64_PRESETS = [
   {id:'tgidemo.c', name:'TGI Graphics Demo (C)'},
   {id:'upandaway.c', name:'Up, Up and Away (C)'},
   {id:'joymove.c', name:'Joystick Movement (C)'},
+  {id:'siegegame.c', name:'Siege Game (C)'},
   {id:'scroll1.c', name:'Scrolling 1 (C)'},
   {id:'scroll2.c', name:'Scrolling 2 (C)'},
   {id:'scroll3.c', name:'Scrolling 3 (C)'},