#include <string.h>

typedef unsigned char byte;
typedef signed char sbyte;
typedef unsigned short word;
typedef enum { false, true } bool;

byte __at (0x0) vidmem[152][256]; // 304x256x4bpp video memory
byte __at (0xc000) palette[16];
volatile byte __at (0xc804) input0;
volatile byte __at (0xc806) input1;
volatile byte __at (0xc80c) input2;
byte __at (0xc900) rom_select;
volatile byte __at (0xcb00) video_counter;
byte __at (0xcbff) watchdog0x39;
byte __at (0xcc00) nvram[0x400];

__sfr __at (0) debug;

// blitter flags
#define SRCSCREEN 0x1
#define DSTSCREEN 0x2
#define ESYNC 0x4
#define FGONLY 0x8
#define SOLID 0x10
#define RSHIFT 0x20
#define EVENONLY 0x40
#define ODDONLY 0x80

struct {
  byte flags;
  byte solid;
  word sstart;
  word dstart;
  byte width;
  byte height;
} __at (0xca00) blitter;

// switch flags
#define UP1 (input0 & 0x1)
#define DOWN1 (input0 & 0x2)
#define LEFT1 (input0 & 0x4)
#define RIGHT1 (input0 & 0x8)
#define START1 (input0 & 0x10)
#define START2 (input0 & 0x20)
#define UP2 (input0 & 0x40)
#define DOWN2 (input0 & 0x80)
#define LEFT2 (input1 & 0x1)
#define RIGHT2 (input1 & 0x2)
#define AUTOUP (input2 & 0x1)
#define ADVANCE (input2 & 0x2)
#define COIN2 (input2 & 0x4)
#define HIGHSCORERESET (input2 & 0x8)
#define COIN1 (input2 & 0x10)
#define COIN3 (input2 & 0x20)
#define TILTSWITCH (input2 & 0x40)
#define SOUNDACK (input2 & 0x80)

#define WATCHDOG watchdog0x39=0x39;

//

void main();
void _sdcc_heap_init(void); // for malloc()

// start routine @ 0x0
// set stack pointer, enable interrupts
void start() {
__asm
        LD      SP,#0xc000
        DI
; copy initialized data
        LD    BC, #l__INITIALIZER
        LD    A, B
        LD    DE, #s__INITIALIZED
        LD    HL, #s__INITIALIZER
        LDIR
__endasm;
  
  _sdcc_heap_init();
  main();
}

#define LOCHAR 0x21
#define HICHAR 0x5e

const byte font8x8[HICHAR-LOCHAR+1][8] = {
{ 0x18,0x18,0x18,0x18,0x00,0x00,0x18,0x00 }, { 0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00 }, { 0x66,0x66,0xff,0x66,0xff,0x66,0x66,0x00 }, { 0x18,0x3e,0x60,0x3c,0x06,0x7c,0x18,0x00 }, { 0x62,0x66,0x0c,0x18,0x30,0x66,0x46,0x00 }, { 0x3c,0x66,0x3c,0x38,0x67,0x66,0x3f,0x00 }, { 0x06,0x0c,0x18,0x00,0x00,0x00,0x00,0x00 }, { 0x0c,0x18,0x30,0x30,0x30,0x18,0x0c,0x00 }, { 0x30,0x18,0x0c,0x0c,0x0c,0x18,0x30,0x00 }, { 0x00,0x66,0x3c,0xff,0x3c,0x66,0x00,0x00 }, { 0x00,0x18,0x18,0x7e,0x18,0x18,0x00,0x00 }, { 0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x30 }, { 0x00,0x00,0x00,0x7e,0x00,0x00,0x00,0x00 }, { 0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x00 }, { 0x00,0x03,0x06,0x0c,0x18,0x30,0x60,0x00 }, { 0x3c,0x66,0x6e,0x76,0x66,0x66,0x3c,0x00 }, { 0x18,0x18,0x38,0x18,0x18,0x18,0x7e,0x00 }, { 0x3c,0x66,0x06,0x0c,0x30,0x60,0x7e,0x00 }, { 0x3c,0x66,0x06,0x1c,0x06,0x66,0x3c,0x00 }, { 0x06,0x0e,0x1e,0x66,0x7f,0x06,0x06,0x00 }, { 0x7e,0x60,0x7c,0x06,0x06,0x66,0x3c,0x00 }, { 0x3c,0x66,0x60,0x7c,0x66,0x66,0x3c,0x00 }, { 0x7e,0x66,0x0c,0x18,0x18,0x18,0x18,0x00 }, { 0x3c,0x66,0x66,0x3c,0x66,0x66,0x3c,0x00 }, { 0x3c,0x66,0x66,0x3e,0x06,0x66,0x3c,0x00 }, { 0x00,0x00,0x18,0x00,0x00,0x18,0x00,0x00 }, { 0x00,0x00,0x18,0x00,0x00,0x18,0x18,0x30 }, { 0x0e,0x18,0x30,0x60,0x30,0x18,0x0e,0x00 }, { 0x00,0x00,0x7e,0x00,0x7e,0x00,0x00,0x00 }, { 0x70,0x18,0x0c,0x06,0x0c,0x18,0x70,0x00 }, { 0x3c,0x66,0x06,0x0c,0x18,0x00,0x18,0x00 }, { 0x3c,0x66,0x6e,0x6e,0x60,0x62,0x3c,0x00 }, { 0x18,0x3c,0x66,0x7e,0x66,0x66,0x66,0x00 }, { 0x7c,0x66,0x66,0x7c,0x66,0x66,0x7c,0x00 }, { 0x3c,0x66,0x60,0x60,0x60,0x66,0x3c,0x00 }, { 0x78,0x6c,0x66,0x66,0x66,0x6c,0x78,0x00 }, { 0x7e,0x60,0x60,0x78,0x60,0x60,0x7e,0x00 }, { 0x7e,0x60,0x60,0x78,0x60,0x60,0x60,0x00 }, { 0x3c,0x66,0x60,0x6e,0x66,0x66,0x3c,0x00 }, { 0x66,0x66,0x66,0x7e,0x66,0x66,0x66,0x00 }, { 0x3c,0x18,0x18,0x18,0x18,0x18,0x3c,0x00 }, { 0x1e,0x0c,0x0c,0x0c,0x0c,0x6c,0x38,0x00 }, { 0x66,0x6c,0x78,0x70,0x78,0x6c,0x66,0x00 }, { 0x60,0x60,0x60,0x60,0x60,0x60,0x7e,0x00 }, { 0x63,0x77,0x7f,0x6b,0x63,0x63,0x63,0x00 }, { 0x66,0x76,0x7e,0x7e,0x6e,0x66,0x66,0x00 }, { 0x3c,0x66,0x66,0x66,0x66,0x66,0x3c,0x00 }, { 0x7c,0x66,0x66,0x7c,0x60,0x60,0x60,0x00 }, { 0x3c,0x66,0x66,0x66,0x66,0x3c,0x0e,0x00 }, { 0x7c,0x66,0x66,0x7c,0x78,0x6c,0x66,0x00 }, { 0x3c,0x66,0x60,0x3c,0x06,0x66,0x3c,0x00 }, { 0x7e,0x18,0x18,0x18,0x18,0x18,0x18,0x00 }, { 0x66,0x66,0x66,0x66,0x66,0x66,0x3c,0x00 }, { 0x66,0x66,0x66,0x66,0x66,0x3c,0x18,0x00 }, { 0x63,0x63,0x63,0x6b,0x7f,0x77,0x63,0x00 }, { 0x66,0x66,0x3c,0x18,0x3c,0x66,0x66,0x00 }, { 0x66,0x66,0x66,0x3c,0x18,0x18,0x18,0x00 }, { 0x7e,0x06,0x0c,0x18,0x30,0x60,0x7e,0x00 }, { 0x3c,0x30,0x30,0x30,0x30,0x30,0x3c,0x00 }, { 0x00,0x60,0x30,0x18,0x0c,0x06,0x03,0x00 }, { 0x3c,0x0c,0x0c,0x0c,0x0c,0x0c,0x3c,0x00 }, { 0x00,0x18,0x3c,0x7e,0x18,0x18,0x18,0x18 }
};

static byte font_table[HICHAR-LOCHAR+1][8*4];

void fill_char_table_entry(char ch) {
  const byte* src = &font8x8[ch-LOCHAR][0];
  byte* data = &font_table[ch-LOCHAR][0];
  int i,j,pixels;
  for (i=0; i<8; i++) {
    byte b = *src++;
    for (j=0; j<4; j++) {
      pixels = 0;
      if (b & 0x80) pixels |= 0xf0;
      if (b & 0x40) pixels |= 0x0f;
      *data++ = pixels;
      b <<= 2;
    }
  }
  WATCHDOG;
}

void fill_char_table() {
  char ch;
  for (ch=LOCHAR; ch<=HICHAR; ch++) {
    fill_char_table_entry(ch);
  }
}

inline word swapw(word j) {
  return ((j << 8) | (j >> 8));
}

// x1: 0-151
// y1: 0-255
inline void blit_solid(byte x1, byte y1, byte w, byte h, byte color) {
  blitter.width = w^4;
  blitter.height = h^4;
  blitter.dstart = x1+y1*256; // swapped
  blitter.solid = color;
  blitter.flags = DSTSCREEN|SOLID;
}

inline void draw_solid(word x1, byte y1, byte w, byte h, byte color) {
  blitter.width = w^4;
  blitter.height = h^4;
  blitter.dstart = (x1>>1)+y1*256; // swapped
  blitter.solid = color;
  blitter.flags = (x1&1) ? DSTSCREEN|SOLID|RSHIFT : DSTSCREEN|SOLID;
}

inline void draw_vline(word x1, byte y1, byte h, byte color) {
  blitter.width = 1^4;
  blitter.height = h^4;
  blitter.dstart = (x1>>1)+y1*256; // swapped
  blitter.solid = color;
  blitter.flags = (x1&1) ? DSTSCREEN|SOLID|ODDONLY : DSTSCREEN|SOLID|EVENONLY;
}

inline void blit_copy(byte x1, byte y1, byte w, byte h, const byte* data) {
  blitter.width = w^4;
  blitter.height = h^4;
  blitter.sstart = swapw((word)data);
  blitter.dstart = x1+y1*256; // swapped
  blitter.flags = DSTSCREEN|FGONLY;
}

inline void blit_copy_solid(byte x1, byte y1, byte w, byte h, const byte* data, byte solid) {
  blitter.width = w^4;
  blitter.height = h^4;
  blitter.sstart = swapw((word)data);
  blitter.dstart = x1+y1*256; // swapped
  blitter.solid = solid;
  blitter.flags = DSTSCREEN|FGONLY|SOLID;
}

// bias sprites by +12 pixels
#define XBIAS 6

inline void draw_sprite(const byte* data, byte x, byte y) {
  blitter.width = data[0]^4;
  blitter.height = data[1]^4;
  blitter.sstart = swapw((word)(data+2));
  blitter.dstart = (x>>1)+y*256+XBIAS; // swapped
  blitter.flags = (x&1) ? DSTSCREEN|FGONLY|RSHIFT : DSTSCREEN|FGONLY;
}

inline void draw_sprite_solid(const byte* data, byte x, byte y, byte color) {
  blitter.width = data[0]^4;
  blitter.height = data[1]^4;
  blitter.sstart = swapw((word)(data+2));
  blitter.dstart = (x>>1)+y*256+XBIAS; // swapped
  blitter.solid = color;
  blitter.flags = (x&1) ? DSTSCREEN|FGONLY|RSHIFT|SOLID : DSTSCREEN|FGONLY|SOLID;
}

void draw_sprite_strided(const byte* data, byte x, byte y, byte stride) {
  byte i;
  byte width = data[0];
  byte height = data[1];
  byte yy = y-(height*(stride-1)/2);
  word dest = (x>>1)+yy*256+XBIAS;
  blitter.width = width^4;
  blitter.height = 1^4;
  for (i=0; i<height; i++) {
    if ((dest & 0xff) < 0x90) {
      blitter.sstart = swapw((word)(data+2));
      blitter.dstart = dest; // swapped
      blitter.flags = DSTSCREEN|FGONLY;
    }
    dest += stride << 8;
    data += width;
  }
}

void erase_sprite_strided(const byte* data, byte x, byte y, byte stride) {
  byte i;
  byte width = data[0];
  byte height = data[1];
  byte yy = y-(height*(stride-1)/2);
  word dest = (x>>1)+yy*256+XBIAS;
  blitter.width = width^4;
  blitter.height = 1^4;
  blitter.solid = 0;
  for (i=0; i<height; i++) {
    if ((dest & 0xff) < 0x90) {
      blitter.dstart = dest; // swapped
      blitter.flags = DSTSCREEN|SOLID;
    }
    dest += stride << 8;
  }
}

inline void draw_char(char ch, byte x, byte y, byte color) {
  if (ch < LOCHAR || ch > HICHAR) return;
  blit_copy_solid(x, y, 4, 8, font_table[ch - LOCHAR], color);
}

void draw_string(const char* str, byte x, byte y, byte color) {
  while (*str) {
    draw_char(*str++, x, y, color);
    x += 4;
  }
}

void draw_box(word x1, byte y1, word x2, byte y2, byte color) {
  draw_solid(x1, y1, (x2-x1)>>1, 1, color);
  draw_solid(x1, y2, (x2-x1)>>1, 1, color);
  draw_vline(x1, y1, y2-y1, color);
  draw_vline(x2, y1, y2-y1, color);
}

// GRAPHIC DATA

const byte palette_data[16] = {
  0x00, 0x03, 0x19, 0x50, 0x52, 0x07, 0x1f, 0x37, 0xe0, 0xa4, 0xfd, 0xff, 0x38, 0x70, 0x7f, 0xf8, };

const byte laser_vert[2+1*8] = {
  1,8,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
};

const byte laser_horiz[2+4*2] = {
  4,2,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
  0xff,
};


const byte playersprite1[] = {
7,16,
0x00,0x00,0xef,0xef,0xe0,0x00,0x00,
0x00,0xee,0xee,0xfe,0xee,0xe0,0x00,
0x0e,0xed,0xef,0xef,0xed,0xee,0x00,
0x0e,0xee,0xdd,0xdd,0xde,0xee,0x00,
0x0e,0xee,0xed,0xde,0xee,0xee,0x00,
0x00,0xee,0xee,0xde,0xee,0xe0,0x00,
0x00,0xee,0xee,0xde,0xee,0xe0,0x00,
0x00,0x00,0xed,0xdd,0xe0,0x00,0x0d,
0xdd,0xdd,0xee,0xee,0xed,0xdd,0xd0,
0x0d,0xee,0xee,0xee,0xee,0xee,0x00,
0x0e,0xe0,0xee,0xee,0xe0,0xee,0x00,
0x0e,0xe0,0xee,0xee,0xe0,0xee,0x00,
0x0e,0xe0,0xdd,0xdd,0xd0,0xde,0x00,
0x0d,0x00,0xee,0x0e,0xe0,0x0d,0x00,
0x00,0x00,0xed,0x0e,0xe0,0x00,0x00,
0x00,0x0d,0xdd,0x0d,0xdd,0x00,0x18,
};

const byte sprite1[2+16*16/2] = {
8,16,
0x00,0x09,0x99,0x00,0x00,0x99,0x90,0x00,
0x00,0x94,0x94,0x90,0x09,0x49,0x49,0x00,
0x04,0x49,0x49,0x90,0x09,0x94,0x94,0x90,
0x94,0x99,0x94,0x90,0x09,0x49,0x99,0x49,
0x99,0x99,0x49,0x93,0x39,0x94,0x99,0x99,
0x04,0x49,0x99,0x94,0x49,0x99,0x94,0x90,
0x00,0x94,0x94,0x43,0x34,0x49,0x49,0x00,
0x00,0x09,0x43,0x94,0x49,0x34,0x90,0x00,
0x00,0x90,0x00,0x39,0x93,0x00,0x09,0x00,
0x00,0x09,0x83,0x33,0x33,0x33,0x90,0x00,
0x00,0x09,0x32,0x23,0x32,0x23,0x90,0x00,
0x00,0x03,0x03,0x23,0x82,0x30,0x30,0x00,
0x03,0x30,0x00,0x33,0x33,0x00,0x03,0x30,
0x00,0x30,0x03,0x00,0x00,0x30,0x03,0x00,
0x00,0x00,0x00,0x30,0x03,0x00,0x00,0x00,
0x00,0x09,0x99,0x00,0x00,0x99,0x90,0x00,
};

const byte sprite2[2+16*16/2] = {
8,16,
0x00,0x94,0x94,0x90,0x09,0x49,0x49,0x00,
0x04,0x49,0x49,0x90,0x09,0x94,0x94,0x90,
0x94,0x99,0x94,0x90,0x09,0x49,0x99,0x49,
0x99,0x99,0x49,0x93,0x39,0x94,0x99,0x99,
0x04,0x49,0x99,0x94,0x49,0x99,0x94,0x90,
0x00,0x94,0x94,0x43,0x34,0x49,0x49,0x00,
0x00,0x09,0x43,0x94,0x49,0x34,0x90,0x00,
0x00,0x90,0x00,0x39,0x93,0x00,0x09,0x00,
0x00,0x09,0x83,0x33,0x33,0x33,0x90,0x00,
0x00,0x09,0x32,0x23,0x32,0x23,0x90,0x00,
0x00,0x03,0x03,0x23,0x82,0x30,0x30,0x00,
0x03,0x30,0x00,0x33,0x33,0x00,0x03,0x30,
0x00,0x30,0x03,0x00,0x00,0x30,0x03,0x00,
0x00,0x00,0x00,0x30,0x03,0x00,0x00,0x00,
0x00,0x00,0x00,0x40,0x00,0x00,0x00,0x00,
};

const byte sprite3[2+16*16/2] = {
8,16,
0x00,0x00,0x00,0x01,0x10,0x00,0x00,0x00,
0x00,0x00,0x00,0x11,0x11,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x10,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x10,0x00,0x00,0x00,
0x00,0x11,0x10,0x01,0x10,0x01,0x11,0x00,
0x11,0x00,0x10,0x11,0x11,0x01,0x00,0x11,
0x10,0x00,0x11,0x11,0x11,0x11,0x00,0x01,
0x10,0x00,0x00,0x11,0x11,0x00,0x00,0x01,
0x00,0x01,0x10,0x11,0x41,0x01,0x10,0x00,
0x00,0x10,0x11,0x11,0x11,0x11,0x01,0x00,
0x01,0x00,0x00,0x51,0x15,0x00,0x00,0x10,
0x01,0x00,0x01,0x10,0x01,0x10,0x00,0x10,
0x01,0x00,0x10,0x00,0x00,0x01,0x00,0x10,
0x00,0x10,0x01,0x00,0x00,0x10,0x01,0x00,
0x00,0x10,0x00,0x00,0x00,0x00,0x01,0x00,
0x00,0x01,0x10,0x00,0x00,0x01,0x10,0x00,
};

const byte sprite4[2+16*16/2] = {
8,16,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0xbb,0xbb,0x00,0x00,0x00,
0x00,0x00,0x00,0xbb,0xbb,0x00,0x00,0x00,
0x00,0x00,0xbb,0xbb,0xbb,0xbb,0x00,0x00,
0x00,0x0b,0x4b,0xbb,0xbb,0xb4,0xb0,0x00,
0x00,0x0b,0x44,0xbb,0xbb,0x49,0xb0,0x00,
0x00,0xbb,0x99,0x4b,0xb4,0x99,0xbb,0x00,
0x00,0x4b,0xb9,0x9b,0xb4,0x4b,0xb4,0x00,
0x00,0x04,0xbb,0x4b,0xb9,0xbb,0x40,0x00,
0x00,0x00,0x4b,0xbb,0xbb,0xb4,0x00,0x00,
0x11,0x00,0x0b,0xbb,0xbb,0xb0,0x00,0x11,
0x10,0x10,0x0b,0x41,0x14,0xb0,0x01,0x01,
0x10,0x00,0x05,0x11,0x11,0x50,0x00,0x01,
0x01,0x00,0x01,0x51,0x15,0x10,0x00,0x10,
0x00,0x10,0x01,0x10,0x01,0x10,0x01,0x00,
0x01,0x01,0x10,0x10,0x01,0x01,0x10,0x10,
};

const byte sprite5[2+16*16/2] = {
8,16,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x22,0x00,0x00,0x22,0x00,0x00,
0x00,0x20,0x20,0x00,0x00,0x02,0x02,0x00,
0x02,0x22,0x12,0x00,0x00,0x21,0x22,0x20,
0x00,0x02,0x11,0x00,0x00,0x11,0x20,0x00,
0x00,0x00,0x02,0x11,0x11,0x20,0x00,0x00,
0x00,0x00,0x02,0x22,0x22,0x20,0x00,0x00,
0x00,0x00,0x21,0x22,0x22,0x12,0x00,0x00,
0x00,0x00,0x22,0x12,0x21,0x22,0x00,0x00,
0x02,0x00,0x22,0x12,0x21,0x22,0x00,0x20,
0x20,0x02,0x21,0x11,0x11,0x12,0x20,0x02,
0x02,0x22,0x15,0x12,0x21,0x51,0x22,0x20,
0x02,0x11,0x15,0x52,0x25,0x51,0x11,0x20,
0x20,0x00,0x22,0x12,0x21,0x22,0x00,0x02,
0x20,0x02,0x20,0x20,0x02,0x02,0x20,0x02,
0x02,0x02,0x00,0x20,0x02,0x00,0x20,0x20,
};

const byte sprite6[2+12*16/2] = {
8,12,
0x00,0x00,0x00,0x00,0x04,0x04,0x04,0x00,
0x00,0x00,0x00,0x00,0x44,0x44,0x44,0x40,
0x00,0x00,0x04,0x04,0x49,0x49,0x99,0x44,
0x00,0x00,0x44,0x44,0x99,0x94,0x44,0x40,
0x00,0x04,0x49,0x99,0x94,0x49,0x99,0x40,
0x00,0x44,0x99,0x94,0x49,0x99,0x44,0x00,
0x04,0x49,0x44,0x99,0x99,0x44,0x00,0x00,
0x04,0x44,0x00,0x49,0x44,0x40,0x00,0x00,
0x04,0x40,0x00,0x04,0x00,0x00,0x00,0x00,
0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
};

const byte sprite7[2+16*16/2] = {
8,16,
0x00,0x60,0x00,0x00,0x00,0x00,0x06,0x00,
0x60,0x60,0x00,0x00,0x00,0x00,0x06,0x06,
0x60,0x60,0x50,0x00,0x00,0x05,0x06,0x06,
0x60,0x60,0x06,0x00,0x00,0x60,0x06,0x06,
0x66,0x60,0x06,0x06,0x60,0x60,0x06,0x66,
0x66,0x60,0x66,0x66,0x66,0x66,0x06,0x66,
0x66,0x60,0x6b,0x6b,0xb6,0xb6,0x06,0x66,
0x06,0x66,0x66,0xb6,0x6b,0x66,0x66,0x60,
0x00,0x67,0x66,0x66,0x66,0x66,0x66,0x00,
0x00,0x11,0x11,0x66,0x66,0x11,0x11,0x00,
0x01,0x11,0x21,0x11,0x11,0x12,0x11,0x10,
0x00,0x10,0x01,0x01,0x10,0x10,0x01,0x00,
0x00,0x10,0x11,0x00,0x00,0x11,0x01,0x00,
0x00,0x00,0x10,0x00,0x00,0x01,0x00,0x00,
};

const byte sprite8[2+16*16/2] = {
8,16,
0x00,0x00,0x11,0x11,0x11,0x11,0x00,0x00,
0x00,0x01,0x61,0x11,0x21,0x12,0x10,0x00,
0x00,0x11,0x12,0x11,0x61,0x11,0x11,0x00,
0x00,0x11,0x71,0x21,0x61,0x17,0x11,0x00,
0x00,0x11,0x77,0x11,0x12,0x77,0x11,0x00,
0x00,0x11,0x17,0x17,0x71,0x72,0x11,0x00,
0x00,0x16,0x21,0x78,0x87,0x11,0x11,0x00,
0x00,0x01,0x81,0x88,0x88,0x18,0x10,0x00,
0x00,0x08,0x18,0x58,0x85,0x81,0x80,0x00,
0x00,0x88,0x01,0x88,0x88,0x10,0x88,0x00,
0x00,0x08,0x07,0x78,0x87,0x70,0x80,0x00,
0x08,0x80,0x07,0x80,0x08,0x70,0x08,0x80,
0x88,0x00,0x88,0x00,0x00,0x88,0x00,0x88,
0x80,0x00,0x08,0x80,0x08,0x80,0x00,0x08,
0x00,0x00,0x00,0x80,0x08,0x00,0x00,0x00,
};

const byte sprite9[2+13*16/2] = {
8,13,
0x00,0x00,0xaa,0x00,0x00,0xaa,0x00,0x00,
0x00,0x00,0xa0,0x0a,0xa0,0x0a,0x00,0x00,
0x0a,0xaa,0xa4,0xaa,0xaa,0x3a,0xaa,0xa0,
0x00,0x0a,0x3a,0x9a,0xa9,0xa3,0xa0,0x00,
0x00,0x0a,0xaa,0x99,0xa4,0xaa,0xa0,0x00,
0x00,0x0a,0xaa,0x99,0x94,0xaa,0xa0,0x00,
0x00,0xaa,0x33,0xaa,0xaa,0x43,0xaa,0x00,
0x0a,0x3a,0xaa,0x3a,0xa3,0xaa,0xa3,0xa0,
0x00,0xaa,0xaa,0x30,0x03,0xaa,0xaa,0x00,
0x00,0x0a,0xa0,0x30,0x03,0x0a,0xa0,0x00,
0x00,0xa3,0xa0,0x00,0x00,0x0a,0x4a,0x00,
0x00,0xaa,0xa0,0x00,0x00,0x0a,0xaa,0x00,
0x00,0x0a,0xa0,0x00,0x00,0x0a,0xa0,0x00,
};

const byte* const all_sprites[9] = {
  sprite1,
  sprite2,
  sprite3,
  sprite4,
  sprite5,
  sprite6,
  sprite7,
  sprite8,
  sprite9,
};

// GAME CODE

typedef struct Actor;

typedef void (*ActorUpdateFn)(struct Actor* a);
typedef void (*ActorDrawFn)(struct Actor* a);

typedef struct Actor {
  struct Actor* next;
  struct Actor** prevptr;
  byte x,y;
  byte* shape;
  ActorUpdateFn update;
  ActorDrawFn draw;
  union {
    struct { sbyte dx,dy; } laser;
    struct { byte exploding; } enemy;
  } u;
} Actor;

#define MAX_ACTORS 128

static Actor actors[MAX_ACTORS];
static Actor* player_list;
static Actor* fast_list;
static Actor* slow_lists[4];
static Actor* obstacle_list;
static Actor* free_list;
static Actor* effects_list;
static byte frame;

#define PLAYER 1
#define LASER 2

void add_actor(Actor** list, Actor* a) {
  if (*list) (*list)->prevptr = &a->next;
  a->next = *list;
  a->prevptr = list;
  *list = a;
}

void remove_actor(Actor* a) {
  if (a->next) a->next->prevptr = a->prevptr;
  *a->prevptr = a->next;
}

char in_rect(const Actor* e, byte x, byte y, byte w, byte h) {
  byte eh = e->shape[0];
  byte ew = e->shape[1];
  return (x >= e->x-w && x <= e->x+ew && y >= e->y-h && y <= e->y+eh);
}

void draw_actor_normal(Actor* a) {
  draw_sprite(a->shape, a->x, a->y);
}

void draw_actor_exploding(Actor* a) {
  erase_sprite_strided(a->shape, a->x, a->y, a->u.enemy.exploding);
  if (a->u.enemy.exploding > 10) {
    a->draw = NULL;
  } else {
    draw_sprite_strided(a->shape, a->x, a->y, ++a->u.enemy.exploding);
  }
}

void update_actor(Actor* a) {
  // if NULL shape, we don't have anything
  if (a->shape) {
    // erase the sprite
    draw_sprite_solid(a->shape, a->x, a->y, 0);
    // call update callback
    if (a->update) {
      a->update(a);
    }
    // did we delete it?
    if (a->shape) {
      // draw the sprite
      if (a->draw) {
        a->draw(a);
      }
    } else {
      // shape became null, remove from list
      remove_actor(a);
    }
  }
}

//

word lfsr = 1;

word rand() {
  byte lsb = lfsr & 1;
  lfsr >>= 1;
  if (lsb) lfsr ^= 0xd400;
  return lfsr;
}

signed char random_dir() {
  byte x = rand();
  if (x < 85) return 0;
  else if (x < 85*2) return -1;
  else return 1;
}

void random_walk(Actor* a) {
  a->x += random_dir();
  a->y += random_dir();
}

static byte g_section;

void update_actor_list(Actor* a) {
  while (a) {
    update_actor(a);
    a = a->next;
  }
}

void update_actors_partial(Actor* a) {
  while (a) {
    if (g_section ^ (a->y < 0x80)) {
      update_actor(a);
    }
    a = a->next;
  }
}

void update_screen_section(byte section) {
  g_section = section;
  update_actors_partial(player_list);
  update_actors_partial(fast_list);
  update_actors_partial(slow_lists[frame & 3]);
}

byte did_overflow() {
  __asm
    ld l,#0
    ret nc
    inc l
  __endasm;
}

static byte test_x, test_y;
static Actor* test_collided;

Actor* test_collision(Actor* a) {
  while (a) {
    if (test_y >= a->y && test_x >= a->x &&
        test_y < a->y+16 && test_x < a->x+16) {
      return a;
    }
    a = a->next;
  }
  return NULL;
}

void laser_move(Actor* a) {
  // did we hit something?
  test_x = a->x;
  test_y = a->y;
  test_collided = test_collision(fast_list);
  if (!test_collided) test_collided = test_collision(slow_lists[0]);
  if (!test_collided) test_collided = test_collision(slow_lists[1]);
  if (!test_collided) test_collided = test_collision(slow_lists[2]);
  if (!test_collided) test_collided = test_collision(slow_lists[3]);
  if (test_collided) {
    // get rid of laser (we can do this in our 'update' fn)
    a->shape = NULL;
    // set exploding flag for enemy (we're not in its update)
    test_collided->draw = draw_actor_exploding;
    test_collided->update = NULL;
    test_collided->u.enemy.exploding = 1;
    remove_actor(test_collided);
    add_actor(&effects_list, test_collided);
    return;
  }
  // move laser
  // check for wall collisions
  a->x += a->u.laser.dx;
  if (a->x > 255-8) a->shape = NULL;
  a->y += a->u.laser.dy;
  if (a->y > 255-8) a->shape = NULL;
}

void shoot_laser(sbyte dx, sbyte dy, const byte* shape) {
  Actor* a = &actors[LASER];
  a->shape = (void*) shape;
  a->x = actors[PLAYER].x + 6;
  a->y = actors[PLAYER].y + 8;
  a->u.laser.dx = dx;
  a->u.laser.dy = dy;
  add_actor(&player_list, a);
}

void player_laser() {
  // is the laser being used?
  if (actors[LASER].shape == NULL) { // no, check controls
    if (UP2) shoot_laser(0,-8,laser_vert);
    else if (DOWN2) shoot_laser(0,8,laser_vert); 
    else if (LEFT2) shoot_laser(-8,0,laser_horiz);
    else if (RIGHT2) shoot_laser(8,0,laser_horiz);
  }
}

void player_move(Actor* a) {
  byte x = a->x;
  byte y = a->y;
  if (UP1) y-=1;
  if (DOWN1) y+=1;
  if (LEFT1) x-=1;
  if (RIGHT1) x+=1;
  a->x = x;
  a->y = y;
  player_laser();
}

static Actor* current_effect;

void effects_new_frame() {
  current_effect = effects_list;
}

void effects_next() {
  if (current_effect) {
    if (current_effect->draw) {
      current_effect->draw(current_effect);
    } else {
      remove_actor(current_effect);
    }
    current_effect = current_effect->next;
  }
}

Actor* new_actor() {
  Actor* a = free_list;
  remove_actor(a);
  return a;
}

void redraw_playfield(Actor* a) {
  a;
  draw_box(0,0,303,255,0x11);
}

Actor* new_effect(ActorDrawFn draw) {
  Actor* a = new_actor();
  a->draw = draw;
  add_actor(&effects_list, a);
  return a;
}

void main() {
  byte i;
  byte num_actors = 32;
  blit_solid(0, 0, 255, 255, 0);
  memset(actors, 0, sizeof(actors));
  memcpy(palette, palette_data, 16);
  fill_char_table();
  player_list = fast_list = obstacle_list = free_list = NULL;
  memset(slow_lists, 0, sizeof(slow_lists));
  // add all actors to free list
  for (i=MAX_ACTORS-1; i>0; i--) {
    add_actor(&free_list, &actors[i]);
  }
  // make actors
  for (i=1; i<num_actors; i++) {
    Actor* a = new_actor();
    do {
      a->x = rand() + rand();
      a->y = rand() + rand();
    } while ((byte)(a->x - 96) < 64 && (byte)(a->y - 96) < 64);
    a->shape = (void*) all_sprites[i%9];
    a->update = random_walk;
    a->draw = draw_actor_normal;
    if (i == PLAYER) {
      a->x = 128;
      a->y = 120;
      add_actor(&player_list, a);
    }
    else if (i == LASER) ; //add_actor(&player_list, a);
    else if (i < 5) add_actor(&fast_list, a);
    else add_actor(&slow_lists[i&3], a);
    WATCHDOG;
  }
  actors[PLAYER].shape = (void*) playersprite1;
  actors[PLAYER].update = player_move;
  actors[LASER].update = laser_move;
  actors[LASER].shape = NULL;
  new_effect(redraw_playfield);
  WATCHDOG;
  while (1) {
    effects_new_frame();
    while (video_counter >= 0x90) effects_next();
    update_screen_section(1);
    while (video_counter < 0x90) effects_next();
    update_screen_section(0);
    switch (frame & 7) {
      case 0:
        draw_box(0,0,303,255,0x11);
        break;
    }
    frame++;
    WATCHDOG;
  }
}