#include <string.h>

typedef unsigned char byte;
typedef signed char sbyte;
typedef unsigned short word;

__sfr __at (0x2) bitshift_offset;
volatile __sfr __at (0x3) bitshift_read;
__sfr __at (0x4) bitshift_value;
__sfr __at (0x6) watchdog_strobe;

byte __at (0x2400) vidmem[224][32]; // 256x224x1 video memory

void main();
// start routine @ 0x0
// set stack pointer, enable interrupts
void start() {
__asm
        LD      SP,#0x2400
        DI
__endasm;
        main();
}

const byte bitmap1[] =
{9,56,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x40,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0x01,0x00,0x00,0x00,0x00,0x80,0xfb,0xff,0xf0,0x01,0x00,0x00,0x00,0x00,0x40,0x04,0x80,0xf3,0x01,0x00,0x00,0x00,0x00,0xb8,0x00,0x00,0xfa,0x01,0x00,0x00,0x00,0x00,0x06,0xfe,0x03,0xfa,0x01,0x00,0x00,0x00,0x00,0x83,0xff,0x03,0xfd,0x01,0x80,0x00,0x00,0x00,0x81,0xcf,0x00,0xfc,0x00,0x80,0x01,0xc0,0x9f,0x01,0x00,0x00,0xfc,0x00,0x80,0x01,0x30,0xe0,0x00,0x00,0x00,0xf8,0x00,0xc0,0x01,0x0c,0x84,0x41,0x00,0x00,0xf8,0x01,0xc0,0x07,0x04,0xf8,0xc2,0x00,0x00,0xf8,0x03,0xc0,0x07,0x06,0x00,0x43,0x00,0x00,0xf2,0x03,0xc0,0x07,0x02,0x80,0x00,0xf8,0x0f,0xe4,0x03,0xe0,0xff,0x04,0xf8,0x00,0xfe,0x1f,0xe8,0x07,0xe0,0x03,0x07,0x80,0x00,0xbe,0x0f,0xec,0x07,0xe0,0x01,0x06,0x80,0x00,0x3c,0x00,0x92,0x07,0xe0,0x00,0x0a,0xff,0x00,0x00,0x00,0x00,0x07,0xe0,0x00,0x24,0x08,0x01,0x00,0x00,0x00,0x07,0x60,0x00,0xc6,0x88,0x01,0x00,0x00,0x00,0x07,0x60,0x00,0x02,0x7e,0x03,0x00,0x00,0x80,0x07,0x60,0x00,0xfe,0x27,0x02,0x00,0x00,0x80,0x07,0x60,0x00,0xc1,0x43,0x02,0x00,0x00,0xc0,0x07,0x70,0xc0,0xc0,0x43,0x04,0x00,0x00,0xc0,0x03,0x70,0x40,0xc1,0x67,0x08,0x00,0x00,0xe0,0x03,0x70,0x00,0xe1,0x7f,0x10,0x00,0x1c,0xf0,0x01,0xf0,0x00,0xfa,0xff,0xa0,0x01,0x7f,0xfe,0x00,0xf0,0x00,0xe2,0x1f,0xc1,0x60,0xfe,0x7f,0x00,0xe0,0x81,0x87,0x0f,0x82,0x81,0xfe,0x3f,0x00,0xe0,0x83,0xc8,0x0f,0x02,0xa5,0xfe,0x0f,0x00,0xe0,0x7f,0xf9,0xbf,0x13,0x9f,0xfd,0x00,0x00,0xe0,0x03,0x81,0xff,0x1f,0x61,0x00,0x00,0x06,0xe0,0x03,0x02,0xfe,0x8f,0x01,0x00,0x6c,0x04,0x80,0x01,0x02,0xfc,0x83,0x01,0x00,0xc0,0x04,0x80,0x01,0x03,0x0e,0x81,0x00,0x04,0x80,0x03,0x80,0x01,0xfe,0x01,0x62,0x50,0x08,0x00,0x00,0x80,0x01,0x48,0x00,0x1c,0x80,0x08,0x00,0x00,0x80,0x03,0x50,0x00,0x1c,0x00,0x07,0x00,0x00,0x80,0x03,0x50,0x00,0x34,0x00,0x00,0x00,0x00,0x80,0x03,0x50,0x00,0x24,0x00,0x00,0x00,0x00,0x80,0x07,0x90,0x00,0x3a,0x00,0x00,0x00,0x00,0x80,0x0f,0x98,0x00,0x10,0x00,0x00,0x00,0x00,0x80,0x3f,0x0c,0x07,0x10,0x00,0x00,0x00,0x00,0x00,0xc1,0x03,0x18,0x08,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0x07,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}
;

void draw_shifted_sprite(const byte* src, byte x, byte y) {
  byte i,j;
  byte* dest = &vidmem[x][y>>3];
  byte w = *src++;
  byte h = *src++;
  bitshift_offset = y & 7;
  for (j=0; j<h; j++) {
    bitshift_value = 0;
    for (i=0; i<w; i++) {
      bitshift_value = *src++;
      *dest++ = bitshift_read;
    }
    bitshift_value = 0;
    *dest++ = bitshift_read;
    dest += 31-w;
  }
}

void clrscr() {
  memset(vidmem, 0, sizeof(vidmem));
}

void main() {
  byte x;
  // TODO: clear memory
  clrscr();
  for (x=0; x<255; x++) {
    draw_shifted_sprite(bitmap1, x, x);
    watchdog_strobe++;
  }
  main();
}