From 25ac41fbde01b17f3ca03fca4224f78bb1b7a09c Mon Sep 17 00:00:00 2001
From: TomW <TomW@localhost>
Date: Sat, 10 Oct 2015 14:33:36 +0100
Subject: [PATCH] Ignore odd/even mode when loading VGA latches on memory read.
 Fixes Jazz Jackrabbit.

---
 src/vid_svga.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/src/vid_svga.c b/src/vid_svga.c
index 1656f3f..891ef78 100644
--- a/src/vid_svga.c
+++ b/src/vid_svga.c
@@ -921,6 +921,7 @@ uint8_t svga_read(uint32_t addr, void *p)
 {
         svga_t *svga = (svga_t *)p;
         uint8_t temp, temp2, temp3, temp4;
+        uint32_t latch_addr;
         int readplane = svga->readplane;
         
         cycles -= video_timing_b;
@@ -931,6 +932,8 @@ uint8_t svga_read(uint32_t addr, void *p)
         addr &= svga->banked_mask;
         addr += svga->read_bank;
 
+        latch_addr = (addr << 2) & 0x7fffff;
+        
 //        pclog("%05X %i %04X:%04X %02X %02X %i\n",addr,svga->chain4,CS,pc, vram[addr & 0x7fffff], vram[(addr << 2) & 0x7fffff], svga->readmode);
 //        pclog("%i\n", svga->readmode);
         if (svga->chain4 || svga->fb_only) 
@@ -953,11 +956,17 @@ uint8_t svga_read(uint32_t addr, void *p)
         
         if (addr >= svga->vram_limit)
            return 0xff;
-           
-        svga->la = svga->vram[addr];
-        svga->lb = svga->vram[addr | 0x1];
-        svga->lc = svga->vram[addr | 0x2];
-        svga->ld = svga->vram[addr | 0x3];
+        
+        if (latch_addr < svga->vram_limit)
+        {   
+                svga->la = svga->vram[latch_addr];
+                svga->lb = svga->vram[latch_addr | 0x1];
+                svga->lc = svga->vram[latch_addr | 0x2];
+                svga->ld = svga->vram[latch_addr | 0x3];
+        }
+        else
+                svga->la = svga->lb = svga->lc = svga->ld = 0xff;
+
         if (svga->readmode)
         {
                 temp   = (svga->colournocare & 1)  ? 0xff : 0;