[Core/MD] improved SVP memory handlers accuracy (fixes Virtua Racing debug mode)

HISTORY.txt

@@ -43,6 +43,7 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
 * added support for Everdrive extended SSF mapper
 * improved console region auto-detection for a few PAL-only games (The Smurfs Travel the World & Williams Arcade's Greatest Hits)
 * improved I2C EEPROM boards emulation accuracy
+* improved SVP memory handlers accuracy (fixes Virtua Racing debug mode)
 * fixed Game Genie / Pro Action Replay lock-on support when Mega CD hardware is enabled 
 * fixed SRAM support in Triple Play 96 & Triple Play - Gold Edition
 * fixed automatic CD loading with .md ROM files

core/cart_hw/md_cart.c

@@ -394,17 +394,6 @@ void md_cart_init(void)
   if (strstr(rominfo.international,"Virtua Racing"))
   {
     svp_init();
-
-    m68k.memory_map[0x30].base    = svp->dram;
-    m68k.memory_map[0x30].read16  = NULL;
-    m68k.memory_map[0x30].write16 = svp_write_dram;
-
-    m68k.memory_map[0x31].base    = svp->dram + 0x10000;
-    m68k.memory_map[0x31].read16  = NULL;
-    m68k.memory_map[0x31].write16 = svp_write_dram;
-
-    m68k.memory_map[0x39].read16  = svp_read_cell_1;
-    m68k.memory_map[0x3a].read16  = svp_read_cell_2;
   }
 
   /**********************************************

core/cart_hw/svp/svp.c

@@ -12,12 +12,69 @@
 
 #include "shared.h"
 
-svp_t *svp = NULL;
+svp_t *svp;
+
+static void svp_write_dram(uint32 address, uint32 data)
+{
+  *(uint16 *)(svp->dram + (address & 0x1fffe)) = data;
+  if (data)
+  {
+    if (address == 0x30fe06) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE06;
+    else if (address == 0x30fe08) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE08;
+  }
+}
+
+static uint32 svp_read_cell_1(uint32 address)
+{
+  address = (address & 0xe002) | ((address & 0x7c) << 6) | ((address & 0x1f80) >> 5);
+  return *(uint16 *)(svp->dram + address);
+}
+
+static uint32 svp_read_cell_2(uint32 address)
+{
+  address = (address & 0xf002) | ((address & 0x3c) << 6) | ((address & 0xfc0) >> 4);
+  return *(uint16 *)(svp->dram + address);
+}
+
+static uint32 svp_read_cell_byte(uint32 address)
+{
+  uint16 data = m68k.memory_map[address >> 16].read16(address);
+
+  if (address & 0x01)
+  {
+    return (data & 0xff);
+  }
+
+  return (data >> 8);
+}
 
 void svp_init(void)
 {
   svp = (void *) ((char *)cart.rom + 0x200000);
   memset(svp, 0, sizeof(*svp));
+
+  m68k.memory_map[0x30].base    = svp->dram;
+  m68k.memory_map[0x30].read8   = NULL;
+  m68k.memory_map[0x30].read16  = NULL;
+  m68k.memory_map[0x30].write8  = NULL;
+  m68k.memory_map[0x30].write16 = svp_write_dram;
+  zbank_memory_map[0x30].read   = NULL;
+  zbank_memory_map[0x30].write  = NULL;
+
+  m68k.memory_map[0x31].base    = svp->dram + 0x10000;
+  m68k.memory_map[0x31].read8   = NULL;
+  m68k.memory_map[0x31].read16  = NULL;
+  m68k.memory_map[0x31].write8  = NULL;
+  m68k.memory_map[0x31].write16 = NULL;
+  zbank_memory_map[0x31].read   = NULL;
+  zbank_memory_map[0x31].write  = NULL;
+
+  m68k.memory_map[0x39].read8   = svp_read_cell_byte;
+  m68k.memory_map[0x39].read16  = svp_read_cell_1;
+  zbank_memory_map[0x39].read   = svp_read_cell_byte;
+  m68k.memory_map[0x3a].read8   = svp_read_cell_byte;
+  m68k.memory_map[0x3a].read16  = svp_read_cell_2;
+  zbank_memory_map[0x3a].read   = svp_read_cell_byte;
 }
 
 void svp_reset(void)
@@ -26,24 +83,3 @@ void svp_reset(void)
   ssp1601_reset(&svp->ssp1601);
 }
 
-void svp_write_dram(uint32 address, uint32 data)
-{
-  *(uint16 *)(svp->dram + (address & 0x1fffe)) = data;
-  if ((address == 0x30fe06) && data) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE06;
-  if ((address == 0x30fe08) && data) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE08;
-}
-
-uint32 svp_read_cell_1(uint32 address)
-{
-  address >>= 1;
-  address = (address & 0x7001) | ((address & 0x3e) << 6) | ((address & 0xfc0) >> 5);
-  return *(uint16 *)(svp->dram + (address & 0x1fffe));
-}
-
-uint32 svp_read_cell_2(uint32 address)
-{
-  address >>= 1;
-  address = (address & 0x7801) | ((address & 0x1e) << 6) | ((address & 0x7e0) >> 4);
-  return *(uint16 *)(svp->dram + (address & 0x1fffe));
-}
-

core/cart_hw/svp/svp.h

@@ -26,8 +26,5 @@ extern svp_t *svp;
 
 extern void svp_init(void);
 extern void svp_reset(void);
-extern void svp_write_dram(uint32 address, uint32 data);
-extern uint32 svp_read_cell_1(uint32 address);
-extern uint32 svp_read_cell_2(uint32 address);
 
 #endif

core/mem68k.c

@@ -2,8 +2,8 @@
  *  Genesis Plus
  *  Main 68k bus handlers
  *
- *  Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003  Charles Mac Donald (original code)
+ *  Copyright (C) 1998-2003  Charles Mac Donald (original code)
- *  Copyright (C) 2007-2015  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2016  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -420,6 +420,19 @@ unsigned int ctrl_io_read_byte(unsigned int address)
     case 0x44:  /* RADICA */
     case 0x50:  /* SVP */
     {
+      if ((address & 0xFC) == 0x00)
+      {
+        unsigned int data = svp->ssp1601.gr[SSP_XST].byte.h;
+        return (address & 1) ? (data & 0xFF) : (data >> 8);
+      }
+
+      if ((address & 0xFE) == 0x04)
+      {
+        unsigned int data = svp->ssp1601.gr[SSP_PM0].byte.h;
+        svp->ssp1601.gr[SSP_PM0].byte.h &= ~1;
+        return (address & 1) ? (data & 0xFF) : (data >> 8);
+      }
+
       return m68k_read_bus_8(address);
     }
 
@@ -536,12 +549,12 @@ unsigned int ctrl_io_read_word(unsigned int address)
 
     case 0x50:  /* SVP */
     {
-      if ((address & 0xFD) == 0)
+      if ((address & 0xFC) == 0x00)
       {
         return svp->ssp1601.gr[SSP_XST].byte.h;
       }
 
-      if ((address & 0xFF) == 4)
+      if ((address & 0xFE) == 0x04)
       {
         unsigned int data = svp->ssp1601.gr[SSP_PM0].byte.h;
         svp->ssp1601.gr[SSP_PM0].byte.h &= ~1;

core/mem68k.h

@@ -2,8 +2,8 @@
  *  Genesis Plus
  *  Main 68k bus handlers
  *
- *  Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003  Charles Mac Donald (original code)
+ *  Copyright (C) 1998-2003  Charles Mac Donald (original code)
- *  Copyright (C) 2007-2015  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2016  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met: