picodrive/pico/sms.c

#include "pico_int.h"
#include "sound/sn76496.h"

static unsigned char vdp_data_read(void)
{
  struct PicoVideo *pv = &Pico.video;
  unsigned char d;

  d = Pico.vramb[pv->addr];
  pv->addr = (pv->addr + 1) & 0x3fff;
  pv->pending = 0;
  return d;
}

static unsigned char vdp_ctl_read(void)
{
  unsigned char d = Pico.video.pending_ints << 7;
  Pico.video.pending = 0;
  Pico.video.pending_ints = 0;

  elprintf(EL_SR, "VDP sr: %02x", d);
  return d;
}

static void vdp_data_write(unsigned char d)
{
  struct PicoVideo *pv = &Pico.video;

  if (pv->type == 3) {
    Pico.cram[pv->addr & 0x1f] = d;
    Pico.m.dirtyPal = 1;
  } else {
    Pico.vramb[pv->addr] = d;
  }
  pv->addr = (pv->addr + 1) & 0x3fff;

  pv->pending = 0;
}

static void vdp_ctl_write(unsigned char d)
{
  struct PicoVideo *pv = &Pico.video;

  if (pv->pending) {
    if ((d >> 6) == 2) {
      pv->reg[d & 0x0f] = pv->addr;
      elprintf(EL_IO, "  VDP r%02x=%02x", d & 0x0f, pv->addr & 0xff);
    }
    pv->type = d >> 6;
    pv->addr &= 0x00ff;
    pv->addr |= (d & 0x3f) << 8;
  } else {
    pv->addr &= 0x3f00;
    pv->addr |= d;
  }
  pv->pending ^= 1;
}

static unsigned char z80_sms_in(unsigned short a)
{
  unsigned char d = 0;

  elprintf(EL_IO, "z80 port %04x read", a);
  a &= 0xc1;
  switch (a)
  {
    case 0x00:
    case 0x01:
      d = 0xff;
      break;

    case 0x40: /* V counter */
      d = Pico.video.v_counter;
      break;

    case 0x41: /* H counter */
      d = Pico.m.rotate++;
      break;

    case 0x80:
      d = vdp_data_read();
      break;

    case 0x81:
      d = vdp_ctl_read();
      break;

    case 0xc0: /* I/O port A and B */
      d = ~((PicoPad[0] & 0x3f) | (PicoPad[1] << 6));
      break;

    case 0xc1: /* I/O port B and miscellaneous */
      d = (Pico.sms_io_ctl & 0x80) | ((Pico.sms_io_ctl << 1) & 0x40) | 0x30;
      d |= ~(PicoPad[1] >> 2) & 0x0f;
      break;
  }

  elprintf(EL_IO, "ret = %02x", d);
  return d;
}

static void z80_sms_out(unsigned short a, unsigned char d)
{
  elprintf(EL_IO, "z80 port %04x write %02x", a, d);
  a &= 0xc1;
  switch (a)
  {
    case 0x01:
      Pico.sms_io_ctl = d;
      break;

    case 0x40:
    case 0x41:
      if (PicoOpt & POPT_EN_PSG)
        SN76496Write(d);
      break;

    case 0x80:
      vdp_data_write(d);
      break;

    case 0x81:
      vdp_ctl_write(d);
      break;
  }
}

static void write_bank(unsigned short a, unsigned char d)
{
  d &= 0x3f; // XXX
  switch (a & 0x0f)
  {
    case 0x0c:
      break;
    case 0x0d:
      if (d != 0)
        elprintf(EL_STATUS|EL_ANOMALY, "bank0 changed to %d!", d);
      break;
    case 0x0e:
      z80_map_set(z80_read_map, 0x4000, 0x7fff, Pico.rom + (d << 14), 0);
#ifdef _USE_CZ80
      Cz80_Set_Fetch(&CZ80, 0x4000, 0x7fff, (UINT32)Pico.rom + (d << 14));
#endif
      break;
    case 0x0f:
      z80_map_set(z80_read_map, 0x8000, 0xbfff, Pico.rom + (d << 14), 0);
#ifdef _USE_CZ80
      Cz80_Set_Fetch(&CZ80, 0x8000, 0xbfff, (UINT32)Pico.rom + (d << 14));
#endif
      break;
  }
}

static void MEMH_FUNC xwrite(unsigned int a, unsigned char d)
{
  elprintf(EL_IO, "z80 write [%04x] %02x", a, d);
  if (a >= 0xc000)
    Pico.zram[a & 0x1fff] = d;
  if (a >= 0xfff0)
    write_bank(a, d);
}

void PicoResetMS(void)
{
  z80_reset();
  PsndReset(); // pal must be known here
}

void PicoPowerMS(void)
{
  memset(&Pico.ram,0,(unsigned int)&Pico.rom-(unsigned int)&Pico.ram);
  memset(&Pico.video,0,sizeof(Pico.video));
  memset(&Pico.m,0,sizeof(Pico.m));
  Pico.m.pal = 0;

  PicoReset();
}

void PicoMemSetupMS(void)
{
  z80_map_set(z80_read_map, 0x0000, 0xbfff, Pico.rom, 0);
  z80_map_set(z80_read_map, 0xc000, 0xdfff, Pico.zram, 0);
  z80_map_set(z80_read_map, 0xe000, 0xffff, Pico.zram, 0);

  z80_map_set(z80_write_map, 0x0000, 0xbfff, xwrite, 1);
  z80_map_set(z80_write_map, 0xc000, 0xdfff, Pico.zram, 0);
  z80_map_set(z80_write_map, 0xe000, 0xffff, xwrite, 1);
 
#ifdef _USE_DRZ80
  drZ80.z80_in = z80_sms_in;
  drZ80.z80_out = z80_sms_out;
#endif
#ifdef _USE_CZ80
  Cz80_Set_Fetch(&CZ80, 0x0000, 0xbfff, (UINT32)Pico.rom);
  Cz80_Set_Fetch(&CZ80, 0xc000, 0xdfff, (UINT32)Pico.zram);
  Cz80_Set_Fetch(&CZ80, 0xe000, 0xffff, (UINT32)Pico.zram);
  Cz80_Set_INPort(&CZ80, z80_sms_in);
  Cz80_Set_OUTPort(&CZ80, z80_sms_out);
#endif
}

void PicoFrameMS(void)
{
  struct PicoVideo *pv = &Pico.video;
  int is_pal = Pico.m.pal;
  int lines = is_pal ? 313 : 262;
  int cycles_line = is_pal ? 58020 : 58293; /* (226.6 : 227.7) * 256 */
  int cycles_done = 0, cycles_aim = 0;
  int lines_vis = 192;
  int y;

  PicoFrameStartMode4();

  for (y = 0; y < lines; y++)
  {
    pv->v_counter = Pico.m.scanline = y;

    if (y < lines_vis)
      PicoLineMode4(y);
    else if (y == lines_vis + 1) {
      Pico.video.pending_ints |= 1;
      if (Pico.video.reg[1] & 0x20) {
        elprintf(EL_INTS, "vint");
        z80_int();
      }
    }

    cycles_aim += cycles_line;
    cycles_done += z80_run((cycles_aim - cycles_done) >> 8) << 8;
  }

  PsndGetSamplesMS();
}