Don't allow CPU backwards VPOSW writes if CPU is not in accurate mode.

diff --git a/custom.cpp b/custom.cpp
index dcc45bd3d68f6c6607c6b2642423ca6e66f63425..e2ab90971c2ebc35d9d07ba2042f086cef4b7f49 100644 (file)
--- a/custom.cpp
+++ b/custom.cpp
@@ -7936,7 +7936,9 @@ static void VHPOSW_delayed(uae_u32 v)
                write_log (_T("VHPOSW %04X PC=%08x\n"), v, M68K_GETPC);
 #endif
 
-       if ((currprefs.m68k_speed >= 0 && !currprefs.cachesize) || copper_access) {
+       bool cpu_accurate = currprefs.m68k_speed >= 0 && !currprefs.cachesize && currprefs.cpu_memory_cycle_exact;
+
+       if (cpu_accurate || copper_access) {
                enabled = true;
                int hpos = hpos_org;
                hnew = (v & 0xff);
@@ -7961,6 +7963,7 @@ static void VHPOSW_delayed(uae_u32 v)
                }
 
                if (hdiff) {
+                       bool fail = false;
                        if (hdiff & 1) {
                                vhposr_delay_offset = 1;
                        }
@@ -7973,6 +7976,8 @@ static void VHPOSW_delayed(uae_u32 v)
                        set_maxhpos(maxhpos);
                        if (newinc && hnew == maxhpos + 1) {
                                // 0000 -> 0001 (0 and 1 are part of previous line, vpos increases when hpos=1). No need to do anything
+                       } else if (hnew_org == 0 && hpos_org > 1) {
+                               fail = true;
                        } else if (hpos < maxhpos && hnew >= maxhpos) {
                                // maxhpos check skip: counter counts until it wraps around 0xFF->0x00
                                int hdiff2 = (0x100 - hnew) - (maxhpos - hpos);
@@ -7993,7 +7998,7 @@ static void VHPOSW_delayed(uae_u32 v)
                        }
 
                        int hpos2 = current_hpos_safe();
-                       if (hpos2 < 0 || hpos2 > 255) {
+                       if (hpos2 < 0 || hpos2 > 255 || fail) {
                                eventtab[ev_hsync].evtime = hsync_evtime;
                                eventtab[ev_hsync].oldcycles = hsync_oldcycles;
                                eventtab[ev_hsynch].evtime = hsynch_evtime;
@@ -8048,27 +8053,29 @@ static void VHPOSW_delayed(uae_u32 v)
        if (enabled && (hpos_org == 0 || hpos_org == 1)) {
                newvpos++;
        }
-       if (newvpos != oldvpos) {
-               vposw_change++;
+       if (newvpos > vpos || (newvpos <= maxvpos && vpos > maxvpos) || cpu_accurate || copper_access) {
+               if (newvpos != oldvpos) {
+                       vposw_change++;
 #ifdef DEBUGGER
-               if (hpos_org >= 0) {
-                       record_dma_hsync(hpos_org);
-                       if (debug_dma) {
-                               int vp = vpos;
-                               vpos = newvpos;
-                               record_dma_hsync(maxhpos);
-                               vpos = vp;
+                       if (hpos_org >= 0) {
+                               record_dma_hsync(hpos_org);
+                               if (debug_dma) {
+                                       int vp = vpos;
+                                       vpos = newvpos;
+                                       record_dma_hsync(maxhpos);
+                                       vpos = vp;
+                               }
                        }
-               }
 #endif
-       }
-       vpos = newvpos;
+               }
+               vpos = newvpos;
 #ifdef DEBUGGER
-       record_dma_denise(hnew, hdiw_denisecounter >> 2);
+               record_dma_denise(hnew, hdiw_denisecounter >> 2);
 #endif
-       vb_check();
-       decide_vline(hnew);
-       vhposw_modified = true;
+               vb_check();
+               decide_vline(hnew);
+               vhposw_modified = true;
+       }
 }
 
 static void VHPOSW_delayed1(uae_u32 v)