[Core/MD] improved MD+ audio track loopback transitions

core/cart_hw/megasd.c

@@ -331,86 +331,112 @@ void megasd_rom_mapper_w(unsigned int address, unsigned int data)
 */
 void megasd_update_cdda(unsigned int samples)
 {
-  /* check if fade out is still in progress */
+  unsigned int count;
-  if (megasd_hw.fadeoutSamplesCount > 0)
+
+  while (samples > 0)
   {
-    /* update remaining fade out samples count */
+    /* attempt to read remaing needed samples by default */
-    megasd_hw.fadeoutSamplesCount -= samples;
+    count = samples;
 
-    /* check end of fade out */
+    /* check against fade out remaining samples */
-    if (megasd_hw.fadeoutSamplesCount <= 0)
+    if ((megasd_hw.fadeoutSamplesCount > 0) && (count > megasd_hw.fadeoutSamplesCount))
     {
-      /* pause audio playback */
+      count = megasd_hw.fadeoutSamplesCount;
-      scd.regs[0x36>>1].byte.h = 0x01;
-      cdd.status = CD_PAUSE;
-
-      /* restore initial volume */
-      cdd.fader[0] = cdd.fader[1] = megasd_hw.fadeoutStartVolume;
     }
-    else
+
+    /* check against playback remaining samples */
+    if ((megasd_hw.playbackSamplesCount > 0) && (count > megasd_hw.playbackSamplesCount))
     {
-      /* force volume for next frame */
+      count = megasd_hw.playbackSamplesCount;
-      cdd.fader[0] = cdd.fader[1] = (megasd_hw.fadeoutSamplesCount * megasd_hw.fadeoutStartVolume) / megasd_hw.fadeoutSamplesTotal;
     }
-  }
 
-  /* Playback in progress ? */
+    /* read required CD-DA samples */
-  if (megasd_hw.playbackSamplesCount > 0)
+    cdd_read_audio(count);
-  {
-    /* update remaining samples count */
-    megasd_hw.playbackSamplesCount -= samples;
 
-    /* check end of current track */
+    /* adjust remaing needed samples count */
-    if (megasd_hw.playbackSamplesCount <= 0)
+    samples -= count;
+
+    /* check if fade out is still in progress */
+    if (megasd_hw.fadeoutSamplesCount > 0)
     {
-      /* check playback end track */
+      /* update remaining fade out samples count */
-      if (cdd.index < megasd_hw.playbackEndTrack)
+      megasd_hw.fadeoutSamplesCount -= count;
+
+      /* check end of fade out */
+      if (megasd_hw.fadeoutSamplesCount <= 0)
       {
-        /* seek start of next track */
+        /* pause audio playback */
-        cdd_seek_audio(cdd.index + 1, cdd.toc.tracks[cdd.index + 1].start);
+        scd.regs[0x36>>1].byte.h = 0x01;
+        cdd.status = CD_PAUSE;
 
-        /* increment current track index */
+        /* restore initial volume */
-        cdd.index++;
+        cdd.fader[0] = cdd.fader[1] = megasd_hw.fadeoutStartVolume;
-
-        /* check if last track is being played */
-        if (cdd.index == megasd_hw.playbackEndTrack)
-        {
-          /* reinitialize remaining samples count using current track start sector and playback end sectors */
-          megasd_hw.playbackSamplesCount = (megasd_hw.playbackEndSector - cdd.toc.tracks[cdd.index].start) * 588;
-        }
-        else
-        {
-          /* reinitialize remaining samples count using current track start and end sectors */
-          megasd_hw.playbackSamplesCount = (cdd.toc.tracks[cdd.index].end - cdd.toc.tracks[cdd.index].start) * 588;
-        }
-      }
-
-      /* check track loop */
-      else if (megasd_hw.playbackLoop)
-      {
-        /* seek back to start track loop sector */
-        cdd_seek_audio(megasd_hw.playbackLoopTrack, megasd_hw.playbackLoopSector);
-
-        /* update current track index */
-        cdd.index = megasd_hw.playbackLoopTrack;
-
-        /* check if single track or successive tracks are being played */
-        if (cdd.index == megasd_hw.playbackEndTrack)
-        {
-          /* reinitialize remaining samples count using playback loop and end sectors */
-          megasd_hw.playbackSamplesCount = (megasd_hw.playbackEndSector - megasd_hw.playbackLoopSector) * 588;
-        }
-        else
-        {
-          /* reinitialize remaining samples count using playback loop sector and track end sector */
-          megasd_hw.playbackSamplesCount = (cdd.toc.tracks[cdd.index].end - megasd_hw.playbackLoopSector) * 588;
-        }
       }
       else
       {
-        /* stop audio playback */
+        /* force volume for next frame */
-        cdd.status = CD_STOP;
+        cdd.fader[0] = cdd.fader[1] = (megasd_hw.fadeoutSamplesCount * megasd_hw.fadeoutStartVolume) / megasd_hw.fadeoutSamplesTotal;
-        scd.regs[0x36>>1].byte.h = 0x01;
+      }
+    }
+
+    /* Playback in progress ? */
+    if (megasd_hw.playbackSamplesCount > 0)
+    {
+      /* update remaining samples count */
+      megasd_hw.playbackSamplesCount -= count;
+
+      /* check end of current track */
+      if (megasd_hw.playbackSamplesCount <= 0)
+      {
+        /* check playback end track */
+        if (cdd.index < megasd_hw.playbackEndTrack)
+        {
+          /* seek start of next track */
+          cdd_seek_audio(cdd.index + 1, cdd.toc.tracks[cdd.index + 1].start);
+
+          /* increment current track index */
+          cdd.index++;
+
+          /* check if last track is being played */
+          if (cdd.index == megasd_hw.playbackEndTrack)
+          {
+            /* reinitialize remaining samples count using current track start sector and playback end sectors */
+            megasd_hw.playbackSamplesCount = (megasd_hw.playbackEndSector - cdd.toc.tracks[cdd.index].start) * 588;
+          }
+          else
+          {
+            /* reinitialize remaining samples count using current track start and end sectors */
+            megasd_hw.playbackSamplesCount = (cdd.toc.tracks[cdd.index].end - cdd.toc.tracks[cdd.index].start) * 588;
+          }
+        }
+
+        /* check track loop */
+        else if (megasd_hw.playbackLoop)
+        {
+          /* seek back to start track loop sector */
+          cdd_seek_audio(megasd_hw.playbackLoopTrack, megasd_hw.playbackLoopSector);
+
+          /* update current track index */
+          cdd.index = megasd_hw.playbackLoopTrack;
+
+          /* check if single track or successive tracks are being played */
+          if (cdd.index == megasd_hw.playbackEndTrack)
+          {
+            /* reinitialize remaining samples count using playback loop and end sectors */
+            megasd_hw.playbackSamplesCount = (megasd_hw.playbackEndSector - megasd_hw.playbackLoopSector) * 588;
+          }
+          else
+          {
+            /* reinitialize remaining samples count using playback loop sector and track end sector */
+            megasd_hw.playbackSamplesCount = (cdd.toc.tracks[cdd.index].end - megasd_hw.playbackLoopSector) * 588;
+          }
+        }
+        else
+        {
+          /* stop audio playback */
+          cdd.status = CD_STOP;
+          scd.regs[0x36>>1].byte.h = 0x01;
+        }
       }
     }
   }

core/cd_hw/cdd.c

@@ -903,12 +903,12 @@ int cdd_load(char *filename, char *header)
             if (cdd.toc.tracks[cdd.toc.last].type)
             {
               /* DATA track length */
-              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) + cdd.sectorSize - 1) / cdd.sectorSize);
+              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + (cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) / cdd.sectorSize);
             }
             else
             {
               /* AUDIO track length */
-              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) + 2351) / 2352);
+              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + (cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) / 2352);
             }
             cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
           }
@@ -1443,9 +1443,6 @@ void cdd_read_audio(unsigned int samples)
   int prev_l = cdd.audio[0];
   int prev_r = cdd.audio[1];
 
-  /* get number of internal clocks (CD-DA samples) needed */
-  samples = blip_clocks_needed(snd.blips[2], samples);
-
   /* audio track playing ? */
   if (!scd.regs[0x36>>1].byte.h && cdd.toc.tracks[cdd.index].fd)
   {
@@ -1646,12 +1643,6 @@ void cdd_read_audio(unsigned int samples)
     /* save last audio output for next frame */
     cdd.audio[0] = prev_l;
     cdd.audio[1] = prev_r;
-
-    /* check CD-DA track end (Mega SD add-on specific)*/
-    if (cart.special & HW_MEGASD)
-    {
-      megasd_update_cdda(samples);
-    }
   }
   else
   {
@@ -1670,6 +1661,23 @@ void cdd_read_audio(unsigned int samples)
   blip_end_frame(snd.blips[2], samples);
 }
 
+void cdd_update_audio(unsigned int samples)
+{
+  /* get number of internal clocks (CD-DA samples) needed */
+  samples = blip_clocks_needed(snd.blips[2], samples);
+
+  if (cart.special & HW_MEGASD)
+  {
+    /* MegaSD add-on specific CD-DA processing */
+    megasd_update_cdda(samples);
+  }
+  else
+  {
+    /* read needed CD-DA samples */
+    cdd_read_audio(samples);
+  }
+}
+
 static void cdd_read_subcode(void)
 {
   uint8 subc[96];

core/cd_hw/cdd.h

@@ -141,6 +141,7 @@ extern void cdd_unload(void);
 extern void cdd_read_data(uint8 *dst, uint8 *subheader);
 extern void cdd_seek_audio(int index, int lba);
 extern void cdd_read_audio(unsigned int samples);
+extern void cdd_update_audio(unsigned int samples);
 extern void cdd_update(void);
 extern void cdd_process(void);
 

core/system.c

@@ -201,8 +201,8 @@ int audio_update(int16 *buffer)
     /* sync PCM chip with other sound chips */
     pcm_update(size);
 
-    /* read CDDA samples */
+    /* read CD-DA samples */
-    cdd_read_audio(size);
+    cdd_update_audio(size);
 
 #ifdef ALIGN_SND
     /* return an aligned number of samples if required */