mcd, add a hack for d32xr

README.md

@@ -20,8 +20,9 @@ At present, most development activity occurs in
 ### Using MSU, MD+/32X+, and Mode 1 on Sega/Mega CD
 
 PicoDrive supports using CD audio enhanced cartridge games in all 3 formats.
-To start an enhanced cartridge, the "cue" or "chd" file of the audio CD must be
-selected. Further instructions can be found in `platform/base_readme.txt`.
+To start an enhanced cartridge, load the .cue or .chd file. The cartridge
+file should have the same base name and be placed in the same directory.
+Further instructions can be found in `platform/base_readme.txt`.
 
 ### Sega Pico and Storyware Pages
 

pico/cd/megasd.c

@@ -82,6 +82,7 @@ static void msd_playtrack(int idx, s32 offs, int loop)
     Pico_msd.result = Pico_msd.command = 0;
     return;
   }
+
   Pico_msd.index = idx-1;
 
   track = &cdd.toc.tracks[Pico_msd.index];
@@ -160,13 +161,19 @@ void msd_update()
         Pico_msd.command = 0;
         if (cdd.lba >= Pico_msd.endlba-1 || cdd.index > Pico_msd.index) {
           if (!Pico_msd.loop || Pico_msd.index < 0) {
-            cdd_stop();
+            cdd_pause();
             // audio done
             Pico_msd.index = -1;
           } else
             cdd_play(Pico_msd.looplba - CDD_PLAY_OFFSET);
         }
       }
+
+      // Hack for D32XR: to prevent BIOS freaking out, pretend drive is "ready"
+      // TODO find out what a real MEGASD is doing with this schizophrenia!
+      u8 state = Pico_mcd->s68k_regs[0x38];
+      Pico_mcd->s68k_regs[0x41] = ~(~Pico_mcd->s68k_regs[0x41] + CD_READY-state) & 0xf;
+      Pico_mcd->s68k_regs[0x38] = CD_READY;
     }
   }
 }