[Core/CD] added support for Wondermega & Wondermega M2/X'Eye specific fader hardware (fixes CD-DA issues and freeze when using Wondermega, Wondermega M2 or X'Eye BIOS)

core/cd_hw/cdd.c

@@ -214,7 +214,7 @@ void cdd_reset(void)
   cdd.status = cdd.loaded ? CD_STOP : NO_DISC;
   
   /* reset CD-DA fader (full volume) */
-  cdd.volume = 0x400;
+  cdd.fader[0] = cdd.fader[1] = 0x400;
 
   /* clear CD-DA output */
   cdd.audio[0] = cdd.audio[1] = 0;
@@ -229,7 +229,7 @@ int cdd_context_save(uint8 *state)
   save_param(&cdd.index, sizeof(cdd.index));
   save_param(&cdd.lba, sizeof(cdd.lba));
   save_param(&cdd.scanOffset, sizeof(cdd.scanOffset));
-  save_param(&cdd.volume, sizeof(cdd.volume));
+  save_param(&cdd.fader, sizeof(cdd.fader));
   save_param(&cdd.status, sizeof(cdd.status));
 
   return bufferptr;
@@ -255,7 +255,7 @@ int cdd_context_load(uint8 *state)
   load_param(&cdd.index, sizeof(cdd.index));
   load_param(&cdd.lba, sizeof(cdd.lba));
   load_param(&cdd.scanOffset, sizeof(cdd.scanOffset));
-  load_param(&cdd.volume, sizeof(cdd.volume));
+  load_param(&cdd.fader, sizeof(cdd.fader));
   load_param(&cdd.status, sizeof(cdd.status));
 
   /* adjust current LBA within track limit */
@@ -1287,10 +1287,10 @@ void cdd_read_audio(unsigned int samples)
     int i, mul, l, r;
 
     /* current CD-DA fader volume */
-    int curVol = cdd.volume;
+    int curVol = cdd.fader[0];
 
     /* CD-DA fader volume setup (0-1024) */
-    int endVol = scd.regs[0x34>>1].w >> 4;
+    int endVol = cdd.fader[1];
 
     /* read samples from current block */
 #if defined(USE_LIBCHDR)
@@ -1476,7 +1476,7 @@ void cdd_read_audio(unsigned int samples)
     }
 
     /* save current CD-DA fader volume */
-    cdd.volume = curVol;
+    cdd.fader[0] = curVol;
 
     /* save last audio output for next frame */
     cdd.audio[0] = prev_l;

core/cd_hw/cdd.h

@@ -64,6 +64,11 @@
 #define NO_DISC  0x0B
 #define CD_END   0x0C
 
+/* CD-DA digital filter types */
+#define CD_TYPE_DEFAULT       0x00
+#define CD_TYPE_WONDERMEGA    0x01
+#define CD_TYPE_WONDERMEGA_M2 0x02
+
 /* CD track */
 typedef struct
 {
@@ -103,11 +108,12 @@ typedef struct
 {
   uint32 cycles;
   uint32 latency;
+  int type;
   int loaded;
   int index;
   int lba;
   int scanOffset;
-  int volume;
+  uint16 fader[2];
   uint8 status;
   uint16 sectorSize;
   toc_t toc;

core/cd_hw/scd.c

@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Mega CD / Sega CD hardware
  *
- *  Copyright (C) 2012-2016  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2018  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -1281,6 +1281,46 @@ static void scd_write_word(unsigned int address, unsigned int data)
       return;
     }
 
+    case 0x34: /* CD Fader */
+    {
+      /* Wondermega hardware (CXD2554M digital filter) */
+      if (cdd.type == CD_TYPE_WONDERMEGA)
+      {
+        /* only MSB is latched by CXD2554M chip, LSB is ignored (8-bit digital filter) */
+        /* attenuator data is 7-bit only (bits 0-7) */
+        data = (data >> 8) & 0x7f;
+
+        /* scale CXD2554M volume (0-127) to full (LC7883KM compatible) volume range (0-1024) */
+        cdd.fader[1] = (1024 * data) / 127 ;
+      }
+
+      /* Wondermega M2 / X'Eye hardware (SM5841A digital filter) */
+      else if (cdd.type == CD_TYPE_WONDERMEGA_M2)
+      {
+        /* only MSB is latched by SM5841A chip, LSB is ignored (8-bit digital filter) */
+        data = data >> 8;
+
+        /* attenuator data is set only when command bit (bit 0) is cleared (other commands are ignored) */
+        if (data & 0x01) return;
+
+        /* attenuator data is 7-bit only (bits 8-1) and reverted (bit 1 = msb) */
+        /* bit reversing formula taken from http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith32Bits */
+        data = (((((data * 0x0802) & 0x22110) | ((data * 0x8020) & 0x88440)) * 0x10101) >> 16) & 0x7f;
+
+        /* convert & scale SM5841A attenuation (127-0) to full (LC7883KM compatible) volume range (0-1024) */
+        cdd.fader[1] = (1024 * (127 - data)) / 127 ;
+      }
+
+      /* default CD hardware (LC7883KM digital filter) */
+      else
+      {
+        /* get LC7883KM volume data (12-bit) */
+        cdd.fader[1] = data >> 4 ;
+      }
+
+      return;
+    }
+
     case 0x4a: /* CDD command 9 (controlled by BIOS, word access only ?) */
     {
       scd.regs[0x4a>>1].w = 0;

core/cd_hw/scd.h

@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Mega CD / Sega CD hardware
  *
- *  Copyright (C) 2012-2016  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2018  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:

core/loadrom.c

@@ -417,6 +417,23 @@ int load_bios(int system)
         /* CD BOOTROM loaded ? */
         if (size > 0)
         {
+          /* auto-detect CD hardware model */
+          if (!memcmp (&scd.bootrom[0x120], "WONDER-MEGA BOOT", 16))
+          {
+            /* Wondermega CD hardware */
+            cdd.type = CD_TYPE_WONDERMEGA;
+          }
+          else if (!memcmp (&scd.bootrom[0x120], "WONDERMEGA2 BOOT", 16))
+          {
+            /* Wondermega M2 / X'Eye CD hardware */
+            cdd.type = CD_TYPE_WONDERMEGA_M2;
+          }
+          else
+          {
+            /* default CD hardware */
+            cdd.type = CD_TYPE_DEFAULT;
+          }
+         
 #ifdef LSB_FIRST
           /* Byteswap ROM to optimize 16-bit access */
           int i;