glue.c

/*
 * Glue		Connects to
 *
 * [CONTROL]
 *  CLK		8 MHz
 *  RESET	RESET
 *  2MHZ	2 Mhz
 *  500KHZ	500 kHz
 * [BUS]
 *  A2-A23	BUS:A1-A23
 *  D0-D1	BUS:D0-D1
 *  FC0-FC1
 *  AS
 *  UDS
 *  LDS
 *  DTACK
 *  BERR
 *  BR
 *  BGI
 *  BGO
 *  BGACK
 * [INTERRUPT]
 *  IACK	MFP:IACK
 *  IPL1	CPU:IPL1
 *  IPL2	CPU:IPL2
 *  MFPINT	MFP:IRQ
 * [CHIP SELECT]
 *  6850CS	2x ACIA:CS0
 *  MFPCS	MFP:CS
 *  SNDCS	PSG:BC1, PSG:BDIR
 *  ROM0-5	ROM
 * [VIDEO]
 *  DE		MMU:DE, SHIFTER:DE, MFP:TBI
 *  VSYNC	MMU:VSYNC, SCREEN:VSYNC
 *  HSYNC	SCREEN:HSYNC
 *  BLANK	SHIFTER:RGB
 * [?]
 *  RAM		MMU:RAM
 *  DEV		MMU:DEV
 *  DMA		MMU:DMA
 *  VMA		CPU:VMA
 *  VPA		CPU:VPA
 *  FCS		?
 *  RDY		?
 */

#include "mmu.h"
#include "mfp.h"
#include "glue.h"
#include "diag.h"

typedef void modefn_t(void);
static modefn_t mode_50, mode_60, mode_71;
static modefn_t *mode_fn;

static int h, v;
static int counter_end;
static int line_end;
static int line;
static int counter;
static int res = 0;
static int freq = 0;

HANDLE_DIAGNOSTICS(glue)

static void set_mode(void)
{
  if(res == 2)
    mode_fn = mode_71;
  else if(freq == 0)
    mode_fn = mode_60;
  else
    mode_fn = mode_50;
}

void glue_set_resolution(int resolution)
{
  TRACE("R%d @ %03d;%03d", resolution, line, counter);
  res = resolution;
  set_mode();
}

void glue_set_sync(int sync)
{
  TRACE("S%d @ %03d;%03d", sync, line, counter);
  freq = sync;
  set_mode();
}

static void vsync(void)
{
  TRACE("Vsync");
  line = 0;
  v = 0;
  mmu_vsync();
  screen_vsync();
}

static void hsync(const char *message)
{
  if(counter == counter_end) {
    CLOCK(message);
    screen_hsync();
    counter = 0;
    line++;
    if(line == line_end)
      vsync();
  }
}

#define CASE(N, X) case N: X; break

static void mode_50(void)
{
  switch(counter) {
  CASE( 28, shifter_blank(0));
  CASE( 54, counter_end = 512);
  CASE( 56, h = 1; cpu_ipl1());
  CASE(256, if(line == 312) cpu_ipl2());
  CASE(376, h = 0);
  CASE(400, if(v) mfp_do_timerb_event(cpu)); //Should be 376
  CASE(450, shifter_blank(1));
  CASE(502,
    switch(line) {
    CASE(  0, line_end = 313);
    CASE( 63, v = 1);
    CASE(263, v = 0);
    });
  default: hsync("PAL horizontal retrace"); break;
  }
}

static void mode_60(void)
{
  switch(counter) {
  CASE( 24, shifter_blank(0));
  CASE( 52, h = 1;  cpu_ipl1());
  CASE( 54, counter_end = 508);
  CASE(256, if(line == 263) cpu_ipl2());
  CASE(372, h = 0);
  CASE(400, if(v) mfp_do_timerb_event(cpu)); //Should be 372
  CASE(450, shifter_blank(1));
  CASE(502,
    switch(line) {
    CASE(  0, line_end = 263);
    CASE( 34, v = 1);
    CASE(234, v = 0);
    });
  default: hsync("NTSC horizontal retrace"); break;
  }
}

static void mode_71(void)
{
  switch(counter) {
  CASE(  4, h = 1; cpu_ipl1());
  CASE( 54, counter_end = 224);
  CASE( 80, if(line == 500) cpu_ipl2());
  CASE(164, h = 0; if(v) mfp_do_timerb_event(cpu));
  //   184, blank on
  CASE(220,
    switch(line) {
    CASE(  0, line_end = 501);
    CASE( 50, v = 1);
    CASE(450, v = 0);
    });
  default: hsync("Monochrome horizontal retrace"); break;
  }
}

void glue_clock(void)
{
  if((counter & 1) == 0) {
    mode_fn();
  }
  mmu_de(h && v);
  shifter_de(h && v);
  counter++;
  ASSERT(counter <= 512);
  ASSERT(line <= line_end);
}

static int wakestate(void)
{
  const char *ws = getenv("WS");
  if(ws == NULL)
    return 0;
  else {
    char *end;
    long clock = strtol(ws, &end, 10);
    if(end == ws) {
      ERROR("Invalid string in WS: %s", ws);
      return 0;
    } else
      return clock;
  }
}

void glue_reset()
{
  glue_set_resolution(0);
  h = v = 0;
  line = 0;
  line_end = 1000;
  counter_end = 1000;
  counter = wakestate();
  INFO("Wakestate %d", counter);
}

void glue_init()
{
  HANDLE_DIAGNOSTICS_NON_MMU_DEVICE(glue, "GLUE");
  glue_reset();
}