From 52962a28a7b368fc1c697d80a439cc53beba6f8b Mon Sep 17 00:00:00 2001
From: PsyK0p4T <87064902+PsyK0p4T@users.noreply.github.com>
Date: Fri, 16 Jun 2023 09:17:21 +0200
Subject: [PATCH] Update MD.ino

Add support for Virtua Racing (E/U/J)
All credits go to Sanni for initial ideas, and Prominos for researches and code.
---
 Cart_Reader/MD.ino | 89 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 81 insertions(+), 8 deletions(-)

diff --git a/Cart_Reader/MD.ino b/Cart_Reader/MD.ino
index 73ba38b..ce3e6df 100644
--- a/Cart_Reader/MD.ino
+++ b/Cart_Reader/MD.ino
@@ -13,6 +13,7 @@ word addrhi;
 word addrlo;
 word chksum;
 boolean is32x = 0;
+boolean isSVP = 0;
 
 //***********************************************
 // EEPROM SAVE TYPES
@@ -183,6 +184,11 @@ void mdLoadConf() {
 }
 #endif
 
+void pulse_clock(int n) {
+  for (int i=0; i<n; i++)
+    PORTH ^= (1 << 1);
+}
+
 /******************************************
    Menu
  *****************************************/
@@ -473,18 +479,24 @@ void setup_MD() {
   // Set Control Pins to Output RST(PH0) CLK(PH1) CS(PH3) WRH(PH4) WRL(PH5) OE(PH6)
   DDRH |= (1 << 0) | (1 << 1) | (1 << 3) | (1 << 4) | (1 << 5) | (1 << 6);
 
-  // Set TIME(PJ0) to Output
-  DDRJ |= (1 << 0);
+  // Set TIME(PJ0), AS(PJ1) to Output
+  DDRJ |= (1 << 0) | (1 << 1);
+
+  //set ASEL(PG5) to Output
+  DDRG |= (1 << 5);
 
   // Set Data Pins (D0-D15) to Input
   DDRC = 0x00;
   DDRA = 0x00;
 
-  // Setting RST(PH0) CLK(PH1) CS(PH3) WRH(PH4) WRL(PH5) OE(PH6) HIGH
-  PORTH |= (1 << 0) | (1 << 1) | (1 << 3) | (1 << 4) | (1 << 5) | (1 << 6);
+  // Setting RST(PH0) CS(PH3) WRH(PH4) WRL(PH5) OE(PH6) HIGH
+  PORTH |= (1 << 0) | (1 << 3) | (1 << 4) | (1 << 5) | (1 << 6);
 
-  // Setting TIME(PJ0) HIGH
-  PORTJ |= (1 << 0);
+  // Setting TIME(PJ0) AS(PJ1) HIGH
+  PORTJ |= (1 << 0) | (1 << 1);
+
+  // setting ASEL(PG5) HIGH
+  PORTG |= (1 << 5);
 
   delay(200);
 
@@ -556,6 +568,12 @@ word readWord_MD(unsigned long myAddress) {
   PORTH &= ~(1 << 3);
   // Setting OE(PH6) LOW
   PORTH &= ~(1 << 6);
+  // Setting AS(PJ1) LOW
+  PORTJ &= ~(1 << 1);
+  // Setting ASEL(PG5) LOW
+  PORTG &= ~(1 << 5);
+  // Pulse CLK(PH1), needed for SVP enhanced carts
+  pulse_clock(10);
 
   // most MD ROMs are 200ns, comparable to SNES > use similar access delay of 6 x 62.5 = 375ns
   NOP;
@@ -572,6 +590,12 @@ word readWord_MD(unsigned long myAddress) {
   PORTH |= (1 << 3);
   // Setting OE(PH6) HIGH
   PORTH |= (1 << 6);
+  // Setting AS(PJ1) HIGH
+  PORTJ |= (1 << 1);
+  // Setting ASEL(PG5) HIGH
+  PORTG |= (1 << 5);
+  // Pulse CLK(PH1), needed for SVP enhanced carts
+  pulse_clock(10);
 
   // these 6x nop delays have been here before, unknown what they mean
   NOP;
@@ -718,6 +742,12 @@ void getCartInfo_MD() {
     id[c + 1] = loByte;
   }
 
+  //Identify games using SVP chip
+  if (!strncmp("GM MK-1229 ", id, 11) || !strncmp("GM G-7001  ", id, 11)) // Virtua Racing (E/U/J)
+    isSVP = 1;
+  else
+    isSVP = 0;
+
   // Fix cartridge sizes according to no-intro database
   if (cartSize == 0x400000) {
     switch (chksum) {
@@ -1414,6 +1444,14 @@ void readROM_MD() {
       PORTH &= ~(1 << 3);
       // Setting OE(PH6) LOW
       PORTH &= ~(1 << 6);
+      // Setting AS(PJ1) LOW
+      PORTJ &= ~(1 << 1);
+      // Setting ASEL(PG5) LOW
+      PORTG &= ~(1 << 5);
+      // Pulse CLK(PH1)
+      if(isSVP)
+        pulse_clock(10);
+
       // most MD ROMs are 200ns, comparable to SNES > use similar access delay of 6 x 62.5 = 375ns
       NOP;
       NOP;
@@ -1430,6 +1468,13 @@ void readROM_MD() {
       PORTH |= (1 << 3);
       // Setting OE(PH6) HIGH
       PORTH |= (1 << 6);
+      // Setting AS(PJ1) HIGH
+      PORTJ |= (1 << 1);
+      // Setting ASEL(PG5) HIGH
+      PORTG |= (1 << 5);
+      // Pulse CLK(PH1)
+      if(isSVP)
+        pulse_clock(10);
 
       // Skip first 256 words
       if (((currBuffer == 0) && (currWord >= 256)) || (currBuffer > 0)) {
@@ -1463,6 +1508,14 @@ void readROM_MD() {
         PORTH &= ~(1 << 3);
         // Setting OE(PH6) LOW
         PORTH &= ~(1 << 6);
+        // Setting AS(PJ1) LOW
+        PORTJ &= ~(1 << 1);
+        // Setting ASEL(PG5) LOW
+        PORTG &= ~(1 << 5);
+        // Pulse CLK(PH1)
+        if(isSVP)
+          pulse_clock(10);
+
         // most MD ROMs are 200ns, comparable to SNES > use similar access delay of 6 x 62.5 = 375ns
         NOP;
         NOP;
@@ -1479,6 +1532,13 @@ void readROM_MD() {
         PORTH |= (1 << 3);
         // Setting OE(PH6) HIGH
         PORTH |= (1 << 6);
+        // Setting AS(PJ1) HIGH
+        PORTJ |= (1 << 1);
+        // Setting ASEL(PG5) HIGH
+        PORTG |= (1 << 5);
+        // Pulse CLK(PH1)
+        if(isSVP)
+          pulse_clock(10);
 
         // Skip first 256 words
         if (((currBuffer == 0) && (currWord >= 256)) || (currBuffer > 0)) {
@@ -1513,6 +1573,14 @@ void readROM_MD() {
         PORTH &= ~(1 << 3);
         // Setting OE(PH6) LOW
         PORTH &= ~(1 << 6);
+        // Setting AS(PJ1) LOW
+        PORTJ &= ~(1 << 1);
+        // Setting ASEL(PG5) LOW
+        PORTG &= ~(1 << 5);
+        // Pulse CLK(PH1)
+        if(isSVP)
+          PORTH ^= (1 << 1);
+
         // most MD ROMs are 200ns, comparable to SNES > use similar access delay of 6 x 62.5 = 375ns
         NOP;
         NOP;
@@ -1529,6 +1597,13 @@ void readROM_MD() {
         PORTH |= (1 << 3);
         // Setting OE(PH6) HIGH
         PORTH |= (1 << 6);
+        // Setting AS(PJ1) HIGH
+        PORTJ |= (1 << 1);
+        // Setting ASEL(PG5) HIGH
+        PORTG |= (1 << 5);
+        // Pulse CLK(PH1)
+        if(isSVP)
+          PORTH ^= (1 << 1);
 
         calcCKSSonic2 += ((buffer[d] << 8) | buffer[d + 1]);
         d += 2;
@@ -2012,7 +2087,6 @@ void EepromInit(byte eepmode) {  // Acclaim Type 2
   PORTL = 0x10;                  // ADDR A16-A23
   PORTA = 0x00;                  // DATA D8-D15
   PORTH |= (1 << 0);             // /RES HIGH
-
   PORTC = eepmode;                 // EEPROM Switch:  0 = Enable (Read EEPROM), 1 = Disable (Read ROM)
   PORTH &= ~(1 << 3);              // CE LOW
   PORTH &= ~(1 << 4) & ~(1 << 5);  // /UDSW + /LDSW LOW
@@ -2250,7 +2324,6 @@ void EepromSet1() {
   }
 }
 
-
 void EepromDevice() {  // 24C02+
   EepromSet1();
   EepromSet0();