mdfr.cpp

   1 // DGen/SDL v1.18+
   2 // Megadrive 1 Frame module
   3 // Many, many thanks to John Stiles for the new structure of this module! :)
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include "md.h"
  10
  11 int split_screen=0;
  12
  13 #ifdef COMPILE_WITH_STAR
  14 void md::run_to_odo_star(int odo_to)
  15 {
  16   int odo_start = s68000readOdometer();
  17   s68000exec(odo_to - odo_start);
  18 }
  19 #endif
  20
  21 #ifdef COMPILE_WITH_MUSA
  22 void md::run_to_odo_musa(int odo_to)
  23 {
  24   odo += m68k_execute(odo_to - odo);
  25 }
  26 #endif
  27
  28 #ifdef COMPILE_WITH_M68KEM
  29 void md::run_to_odo_m68kem(int odo_to)
  30 {
  31   odo += m68000_execute(odo_to - odo);
  32 }
  33 #endif
  34
  35 void md::run_to_odo_z80(int odo_to)
  36 {
  37   if(z80_online)
  38     {
  39       odo_to >>= 1;
  40       int odo_start = mz80GetElapsedTicks(0);
  41       mz80exec(odo_to - odo_start);
  42     }
  43 }
  44
  45 #define LINES_PER_FRAME_NTSC 0x106 // Number of scanlines in NTSC (w/ vblank)
  46 #define LINES_PER_FRAME_PAL  0x138 // Number of scanlines in PAL  (w/ vblank)
  47
  48 #define LINES_PER_FRAME (pal? LINES_PER_FRAME_PAL : LINES_PER_FRAME_NTSC)
  49
  50 #define VBLANK_LINE_NTSC 0xE0 // vblank location for NTSC (and PAL 28-cel mode)
  51 #define VBLANK_LINE_PAL  0xF0 // vblank location for PAL 30-cel mode
  52
  53 #define VBLANK_LINE ((pal && (vdp.reg[1] & 8))? \
  54                      VBLANK_LINE_PAL : VBLANK_LINE_NTSC)
  55
  56 #define scanlength (pal? (7189547/50/0x138) : (8000000/60/0x106))
  57
  58 #ifdef COMPILE_WITH_STAR
  59 int md::one_frame_star(struct bmap *bm, unsigned char retpal[256], struct sndinfo *sndi)
  60 {
  61   int hints, odom = 0;
  62
  63   star_mz80_on(); // VERY IMPORTANT! Must call before using star/mz80
  64
  65   // Clear odos
  66   s68000tripOdometer();
  67   mz80GetElapsedTicks(1);
  68
  69   // Raster zero causes special things to happen :)
  70   coo4 = 0x37; // Init status register
  71   if(vdp.reg[12] & 0x2) coo5 ^= 0x10; // Toggle odd/even for interlace
  72   if(vdp.reg[1]  & 0x40) coo5 &= ~0x88; // Clear vblank and vint
  73   if(!(vdp.reg[1] & 0x20)) coo5 |= 0x80; // If vint disabled, vint happened
  74                                          // is permanently set
  75   hints = vdp.reg[10]; // Set hint counter
  76
  77   // Video display! :D
  78   for(ras = 0; ras < VBLANK_LINE; ++ras)
  79     {
  80       fm_timer_callback(); // update sound timers
  81
  82       if((vdp.reg[0] & 0x10) && (--hints < 0))
  83         {
  84           // Trigger hint
  85           s68000interrupt(4, -1);
  86           hints = vdp.reg[10];
  87           may_want_to_get_pic(bm, retpal, 1);
  88         } else
  89           may_want_to_get_pic(bm, retpal, 0);
  90
  91       coo5 |= 4; // hblank comes before, about 36/209 of the whole scanline
  92       run_to_odo_star(odom + (scanlength * 36/209));
  93       // Do hdisplay now
  94       odom += scanlength;
  95       coo5 &= ~4;
  96       run_to_odo_star(odom);
  97
  98       // Do Z80
  99       run_to_odo_z80(odom);
 100     }
 101   // Now we're in vblank, more special things happen :)
 102   // Blank everything, and trigger vint
 103   coo5 |= 0x8C;
 104   if(vdp.reg[1] & 0x20) s68000interrupt(6, -1);
 105   if(z80_online) mz80int(0);
 106
 107   // Run the course of vblank
 108   for(; ras < LINES_PER_FRAME; ++ras)
 109     {
 110       fm_timer_callback();
 111
 112       // No interrupts happen in vblank
 113
 114       odom += scanlength;
 115       run_to_odo_star(odom);
 116       run_to_odo_z80(odom);
 117     }
 118
 119   // Fill the sound buffers
 120   if(sndi) may_want_to_get_sound(sndi);
 121
 122   // Shut off mz80/star - VERY IMPORTANT!
 123   star_mz80_off();
 124
 125   return 0;
 126 }
 127 #endif // COMPILE_WITH_STAR
 128
 129 #ifdef COMPILE_WITH_MUSA
 130 int md::one_frame_musa(struct bmap *bm, unsigned char retpal[256], struct sndinfo *sndi)
 131 {
 132   int hints, odom = 0;
 133
 134   star_mz80_on(); // VERY IMPORTANT! Must call before using star/mz80
 135
 136   // Clear odos
 137   odo = 0;
 138   mz80GetElapsedTicks(1);
 139
 140   // Raster zero causes special things to happen :)
 141   coo4 = 0x37; // Init status register
 142   if(vdp.reg[12] & 0x2) coo5 ^= 0x10; // Toggle odd/even for interlace
 143   if(vdp.reg[1]  & 0x40) coo5 &= ~0x88; // Clear vblank and vint
 144   if(!(vdp.reg[1] & 0x20)) coo5 |= 0x80; // If vint disabled, vint happened
 145                                          // is permanently set
 146   hints = vdp.reg[10]; // Set hint counter
 147
 148   // Video display! :D
 149   for(ras = 0; ras < VBLANK_LINE; ++ras)
 150     {
 151       fm_timer_callback(); // update sound timers
 152
 153       if((vdp.reg[0] & 0x10) && (--hints < 0))
 154         {
 155           // Trigger hint
 156           m68k_assert_irq(4); m68k_clear_irq(4);
 157           hints = vdp.reg[10];
 158           may_want_to_get_pic(bm, retpal, 1);
 159         } else may_want_to_get_pic(bm, retpal, 0);
 160       coo5 |= 4; // hblank comes before, about 36/209 of the whole scanline
 161       run_to_odo_musa(odom + (scanlength * 36/209));
 162       // Do hdisplay now
 163       odom += scanlength;
 164       coo5 &= ~4;
 165       run_to_odo_musa(odom);
 166
 167       // Do Z80
 168       run_to_odo_z80(odom);
 169     }
 170   // Now we're in vblank, more special things happen :)
 171   // Blank everything, and trigger vint
 172   coo5 |= 0x8C;
 173   if(vdp.reg[1] & 0x20) { m68k_assert_irq(6); m68k_clear_irq(6); }
 174   if(z80_online) mz80int(0);
 175
 176   // Run the course of vblank
 177   for(; ras < LINES_PER_FRAME; ++ras)
 178     {
 179       fm_timer_callback();
 180
 181       // No interrupts happen in vblank :)
 182
 183       odom += scanlength;
 184       run_to_odo_musa(odom);
 185       run_to_odo_z80(odom);
 186     }
 187
 188   // Fill the sound buffers
 189   if(sndi) may_want_to_get_sound(sndi);
 190
 191   // Shut off mz80/star - VERY IMPORTANT!
 192   star_mz80_off();
 193
 194   return 0;
 195 }
 196 #endif // COMPILE_WITH_MUSA
 197
 198 // FIXME: I'm not going to do this until I figure out 68kem better
 199 #ifdef COMPILE_WITH_M68KEM
 200 int md::one_frame_m68kem(struct bmap *bm, unsigned char retpal[256], struct sndinfo *sndi)
 201 {}
 202 #endif
 203
 204 int md::one_frame(
 205   struct bmap *bm,unsigned char retpal[256],
 206   struct sndinfo *sndi)
 207 {
 208   ++frame;
 209   switch(cpu_emu)
 210     {
 211 #ifdef COMPILE_WITH_STAR
 212       case 0: return one_frame_star(bm, retpal, sndi);
 213 #endif
 214 #ifdef COMPILE_WITH_MUSA
 215       case 1: return one_frame_musa(bm, retpal, sndi);
 216 #endif
 217 #ifdef COMPILE_WITH_M68KEM
 218       case 2: return one_frame_m68kem(bm, retpal, sndi);
 219 #endif
 220       // Something's screwy here...
 221       default: return 1;
 222     }
 223 }
 224
 225 int md::calculate_hcoord()
 226 {
 227   int x=0,hcoord;
 228   // c00009 is the H counter (I believe it's (h-coord>>1)&0xff)
 229 #ifdef COMPILE_WITH_STAR
 230   if (cpu_emu==0) x = s68000readOdometer() - (ras * scanlength);
 231 #endif
 232 #if defined(COMPILE_WITH_MUSA) || defined(COMPILE_WITH_M68KEM)
 233   if (cpu_emu==1) x = odo - (ras * scanlength);
 234 #endif
 235
 236   // hcoord=-56 (inclusive) to 364 (inclusive) in 40 column mode
 237
 238   hcoord=(x*416)/scanlength;
 239   hcoord-=56;
 240
 241   return hcoord;
 242 }
 243
 244 unsigned char md::calculate_coo8()
 245 {
 246   int hvcount;
 247   hvcount=ras;
 248
 249   // c00008 is the V counter
 250   if (calculate_hcoord()>=330) hvcount++;
 251     // v counter seems to be a bit ahead of where h counter wraps
 252
 253   if (hvcount>(VBLANK_LINE+0xa)) hvcount-=6; // vcounter E5-EA appears twice!
 254
 255   hvcount&=0xff;
 256   return hvcount;
 257 }
 258
 259 unsigned char md::calculate_coo9()
 260 {
 261   int coo9;
 262   coo9=(calculate_hcoord()>>1)&0xff;
 263
 264   return coo9;
 265 }
 266
 267
 268 // *************************************
 269 //       May want to get pic or sound
 270 // *************************************
 271
 272 inline int md::may_want_to_get_pic(struct bmap *bm,unsigned char retpal[256],int/*mark*/)
 273 {
 274   if (bm==NULL) return 0;
 275
 276   if (ras>=0 && ras<VBLANK_LINE )
 277     vdp.draw_scanline(bm, ras);
 278   if(retpal && ras == 100) get_md_palette(retpal, vdp.cram);
 279   return 0;
 280 }
 281
 282 int md::may_want_to_get_sound(struct sndinfo *sndi)
 283 {
 284   int i, len = sndi->len;
 285   int in_dac, cur_dac = 0, acc_dac = len;
 286   int *dac = dac_data - 1;
 287
 288   // Get the PSG
 289   SN76496Update_16(0, sndi->l, len);
 290
 291   // We bring in the dac, but stretch it out to fit the real length.
 292   for(i = 0; i < len; ++i)
 293     {
 294       acc_dac += LINES_PER_FRAME;
 295       if(acc_dac >= len)
 296         {
 297           acc_dac -= len;
 298           in_dac = *(++dac);
 299           if(in_dac != 1) cur_dac = in_dac;
 300         }
 301       sndi->l[i] += cur_dac;
 302     }
 303   // Copy mono signal to center channel
 304   memcpy(sndi->r, sndi->l, len * sizeof(short));
 305
 306   // Add in the stereo FM buffer
 307   FMSAMPLE *buf[2];
 308   buf[0] = (FMSAMPLE*) sndi->l;
 309   buf[1] = (FMSAMPLE*) sndi->r;
 310   YM2612UpdateOne(0, (void**)buf, len);
 311
 312   // Clear the dac for next frame
 313   dac_clear();
 314   return 0;
 315 }
 316