Fixed VC to act like a real Jaguar. :-)

[virtualjaguar] / src / jaguar.cpp

diff --git a/src/jaguar.cpp b/src/jaguar.cpp
index df4c139afc4ab061396301cacdd93a2bf2aa118e..f623817e98956273f09d404d911a0544e3aafd5a 100644 (file)
--- a/src/jaguar.cpp
+++ b/src/jaguar.cpp
@@ -68,6 +68,7 @@ uint32 jaguar_active_memory_dumps = 0;
 
 uint32 jaguarMainROMCRC32, jaguarROMSize, jaguarRunAddress;
 bool jaguarCartInserted = false;
+bool lowerField = false;
 
 #ifdef CPU_DEBUG_MEMORY
 uint8 writeMemMax[0x400000], writeMemMin[0x400000];
@@ -1650,6 +1651,7 @@ void JaguarInit(void)
 //Seems to want $01010101... Dunno why. Investigate!
        memset(jaguarMainROM, 0x01, 0x600000);  // & set it to all 01s...
 //     memset(jaguar_mainRom, 0xFF, 0x600000); // & set it to all Fs...
+       lowerField = false;                                                             // Reset the lower field flag
 
        m68k_set_cpu_type(M68K_CPU_TYPE_68000);
        GPUInit();
@@ -1683,6 +1685,7 @@ void JaguarReset(void)
     m68k_pulse_reset();                                                                // Reset the 68000
        WriteLog("Jaguar: 68K reset. PC=%06X SP=%08X\n", m68k_get_reg(NULL, M68K_REG_PC), m68k_get_reg(NULL, M68K_REG_A7));
 
+       lowerField = false;                                                             // Reset the lower field flag
        // New timer base code stuffola...
        InitializeEventList();
 //     SetCallbackTime(ScanlineCallback, 63.5555);
@@ -1957,7 +1960,8 @@ void JaguarExecuteNew(void)
 // The thing to keep in mind is that the VC is advanced every HALF line, regardless
 // of whether the display is interlaced or not. The only difference with an
 // interlaced display is that the high bit of VC will be set when the lower
-// field is being rendered.
+// field is being rendered. (NB: The high bit of VC is ALWAYS set on the lower field,
+// regardless of whether it's in interlace mode or not.)
 //
 // Normally, TVs will render a full frame in 1/30s (NTSC) or 1/25s (PAL) by
 // rendering two fields that are slighty vertically offset from each other.
@@ -1988,18 +1992,26 @@ void HalflineCallback(void)
        // So we cut the number of half-lines in a frame in half. :-P
        uint16 numHalfLines = ((vjs.hardwareTypeNTSC ? 525 : 625) * 2) / 2;
 
-       if (vc >= numHalfLines)
+       if ((vc & 0x7FF) >= numHalfLines)
 #else
-       if (vc >= vp)
+       if ((vc & 0x7FF) >= vp)
 #endif
+       {
                vc = 0;
+               lowerField = !lowerField;
+
+               // If we're rendering the lower field, set the high bit (#12, counting
+               // from 1) of VC
+               if (lowerField)
+                       vc = 0x0800;
+       }
 
 //WriteLog("SLC: Currently on line %u (VP=%u)...\n", vc, vp);
        TOMWriteWord(0xF00006, vc, JAGUAR);
 
 //This is a crappy kludge, but maybe it'll work for now...
 //Maybe it's not so bad, since the IRQ happens on a scanline boundary...
-       if (vc == vi && vc > 0 && TOMIRQEnabled(IRQ_VIDEO))     // Time for Vertical Interrupt?
+       if ((vc & 0x7FF) == vi && (vc & 0x7FF) > 0 && TOMIRQEnabled(IRQ_VIDEO)) // Time for Vertical Interrupt?
        {
                // We don't have to worry about autovectors & whatnot because the Jaguar
                // tells you through its HW registers who sent the interrupt...
@@ -2011,7 +2023,7 @@ void HalflineCallback(void)
 
 //Change this to VBB???
 //Doesn't seem to matter (at least for Flip Out & I-War)
-       if (vc == 0)
+       if ((vc & 0x7FF) == 0)
 //     if (vc == vbb)
        {
                JoystickExec();