From 75ac3317ed9f6964ffdde441ff27ee666ff0df6f Mon Sep 17 00:00:00 2001
From: EkeEke <ekeeke31@gmail.com>
Date: Sun, 30 Jun 2013 13:06:04 +0200
Subject: [PATCH] [Core/Input] cleaner fix for lightgun emulation when HVC
 latch is disabled (better not make VDP core hackish)

---
 core/input_hw/lightgun.c | 22 +++++++++++++++++++---
 core/vdp_ctrl.c          | 23 ++++++++---------------
 2 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/core/input_hw/lightgun.c b/core/input_hw/lightgun.c
index 4ed0b76..d6bf46e 100644
--- a/core/input_hw/lightgun.c
+++ b/core/input_hw/lightgun.c
@@ -129,14 +129,25 @@ void lightgun_refresh(int port)
           }
         }
 
-        /* External Interrupt ? */
+        /* External Interrupt enabled ? */
         if (reg[11] & 0x08) 
         {
           m68k_update_irq(2);
         }
 
-        /* HACK: force HV Counter latch (some games does not lock HV Counter but instead use larger offset value) */
-        hvc_latch = 0x10000 | (y << 8);
+        /* HVC latch enabled ? */
+        if (reg[0] & 0x02)
+        {
+          /* line accurate V-Counter value */
+          hvc_latch = 0x10000 | (y << 8);
+        }
+        else
+        {
+          /* HACK: force HVC latch even when disabled (a few games does not lock HV Counter but instead applies larger offset value) */
+          hvc_latch = 0x20000 | (y << 8);
+        }
+
+        /* pixel accurate H-Counter value */
         if (reg[12] & 1) 
         {
           hvc_latch |= hc_320[((x / 2) + input.x_offset) % 210];
@@ -147,6 +158,11 @@ void lightgun_refresh(int port)
         }
       }
     }
+    else if (hvc_latch & 0x20000)
+    {
+      /* HVC should be free-running on other lines when latch is disabled (fixes "Gunfight - 3 in 1" randomization) */
+      hvc_latch = 0;
+    }
   }
 }
 
diff --git a/core/vdp_ctrl.c b/core/vdp_ctrl.c
index e2fe42e..b9df03e 100644
--- a/core/vdp_ctrl.c
+++ b/core/vdp_ctrl.c
@@ -1362,7 +1362,7 @@ unsigned int vdp_hvc_r(unsigned int cycles)
   int vc;
   unsigned int data = hvc_latch;
 
-  /* Check if HVC is frozen */
+  /* Check if HVC latch is enabled */
   if (!data)
   {
     /* Cycle-accurate HCounter (Striker, Mickey Mania, Skitchin, Road Rash I,II,III, Sonic 3D Blast...) */
@@ -1370,26 +1370,18 @@ unsigned int vdp_hvc_r(unsigned int cycles)
   }
   else
   {
-    /* Mode 5: HV counters are frozen (cf. lightgun games & Sunset Riders) */
-    if (reg[1] & 4)
+    /* Mode 5: H & V counters are frozen (cf. lightgun games, Sunset Riders logo) */
+    if (reg[1] & 0x04)
     {
-      /* check if HVC is really locked or is read within INT2 callback (HVC latch is forced for lightgun emulation, cf. lightgun.c) */
-      if ((reg[0] & 0x02) || (m68k.int_mask == 0x0200))
-      {
 #ifdef LOGVDP
-        error("[%d(%d)][%d(%d)] HVC read -> 0x%x (%x)\n", v_counter, (cycles/MCYCLES_PER_LINE-1)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, data & 0xffff, m68k_get_reg(M68K_REG_PC));
+      error("[%d(%d)][%d(%d)] HVC latch read -> 0x%x (%x)\n", v_counter, (cycles/MCYCLES_PER_LINE-1)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, data & 0xffff, m68k_get_reg(M68K_REG_PC));
 #endif
-        /* return latched HVC value */
-        return (data & 0xffff);
-      }
-
-      /* HV counters should be free-running (fixes "Gunfight - 3 in 1" randomization when Justifiers are enabled) */
-      hvc_latch = 0;
-      data = hctab[cycles % MCYCLES_PER_LINE];
+      /* return latched HVC value */
+      return (data & 0xffff);
     }
     else
     {
-      /* Mode 4: V counter runs normally, H counter is frozen */
+      /* Mode 4: by default, V counter runs normally & H counter is frozen */
       data &= 0xff;
     }
   }
@@ -1413,6 +1405,7 @@ unsigned int vdp_hvc_r(unsigned int cycles)
     vc = (vc & ~1) | ((vc >> 8) & 1);
   }
 
+  /* return HCounter in LSB & VCounter in MSB */
   data |= ((vc & 0xff) << 8);
   
 #ifdef LOGVDP