Accurate BPLCON2 invalid PFx value emulation.

diff --git a/drawing.cpp b/drawing.cpp
index 6c82bfb32d08ba975db203c1c8d761f12eb3122f..6326c0dfb12a594ba2aae1138b6390a115c349e6 100644 (file)
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -2177,16 +2177,12 @@ static void gen_pfield_tables (void)
 
                if (plane2 > 0)
                        plane2 += 8;
-               dblpf_ind1[i] = i >= 128 ? i & 0x7F : (plane1 == 0 ? plane2 : plane1);
-               dblpf_ind2[i] = i >= 128 ? i & 0x7F : (plane2 == 0 ? plane1 : plane2);
-
-               // Hack for OCS/ECS-only dualplayfield chipset bug.
-               // If PF2P2 is invalid (>5), playfield color becomes transparent but
-               // playfield still hides playfield under it! (if plfpri is set)
-               if (i & 64) {
-                       dblpf_ind2[i] = 0;
-                       dblpf_ind1[i] = 0;
-               }
+               // use OCS/ECS unused plane bits 6 and 7 for 
+               // dualplayfield BPLCON2 invalid value emulation.
+               int plane1x = (i & 0x40) ? 0 : plane1;
+               int plane2x = (i & 0x80) ? 0 : plane2;
+               dblpf_ind1[i] = plane1 == 0 ? plane2x : plane1x;
+               dblpf_ind2[i] = plane2 == 0 ? plane1x : plane2x;
 
                sprite_offs[i] = (i & 15) ? 0 : 2;
 
@@ -2295,29 +2291,30 @@ static void weird_bitplane_fix (int start, int end)
 
        start >>= sh;
        end >>= sh;
-       if (bplplanecnt == 5 && !bpldualpf && plf2pri > 5) {
-               /* emulate OCS/ECS only undocumented "SWIV" hardware feature */
-               for (int i = start; i < end; i++) {
-                       if (p[i] & 16)
-                               p[i] = 16;
+       if (!bpldualpf) {
+               // HAM is unaffected (probably because plane 5 is HAM control bit)
+               if (bplham)
+                       return;
+               if (bplplanecnt >= 5 && plf2pri >= 5) {
+                       // Emulate OCS/ECS only undocumented "SWIV" hardware feature:
+                       // PF2 >= 5 and bit in plane 5 set: other planes are ignored in color selection.
+                       for (int i = start; i < end; i++) {
+                               if (p[i] & 0x10)
+                                       p[i] = 0x10;
+                       }
                }
-       } 
-       if (bpldualpf && bpldualpfpri && plf2pri > 4) {
-               /* in dualplayfield mode this feature is even more strange.. */
+       } else if (plf1pri >= 5 || plf2pri >= 5) {
+               // If PFx is invalid (>=5), matching playfield's color becomes transparent
+               // (COLOR00). Priorities keep working normally: "transparent" playfield
+               // will still hide lower priority playfield behind it.
+               // Logo in Running man / Scoopex
+               uae_u8 mask1 = 0x01 | 0x04 | 0x10;
+               uae_u8 mask2 = 0x02 | 0x08 | 0x20;
                for (int i = start; i < end; i++) {
-                       // running man / scoopex
-                       if (p[i] & (2 | 8 | 32))
+                       if (plf1pri >= 5 && (p[i] & mask1))
                                p[i] |= 0x40;
-               }
-       }
-       if (bpldualpf && !bpldualpfpri && plf2pri > 4) {
-               for (int i = start; i < end; i++) {
-                       p[i] &= ~(2 | 8 | 32);
-               }
-       }
-       if (bpldualpf && plf1pri > 4) {
-               for (int i = start; i < end; i++) {
-                       p[i] = 0x40;
+                       if (plf2pri >= 5 && (p[i] & mask2))
+                               p[i] |= 0x80;
                }
        }
 }
@@ -2847,7 +2844,7 @@ static void do_color_changes (line_draw_func worker_border, line_draw_func worke
                // playfield
                if (nextpos_in_range > lastpos && lastpos >= playfield_start && lastpos < playfield_end) {
                        int t = nextpos_in_range <= playfield_end ? nextpos_in_range : playfield_end;
-                       if ((plf2pri > 4 || plf1pri > 4) && !(currprefs.chipset_mask & CSMASK_AGA))
+                       if ((plf2pri >= 5 || plf1pri >= 5) && !(currprefs.chipset_mask & CSMASK_AGA))
                                weird_bitplane_fix (lastpos, t);
                        if (bplxor && may_require_hard_way && worker_pfield != pfield_do_linetoscr_bordersprite_aga)
                                playfield_hard_way(worker_pfield, lastpos, t);
@@ -3012,10 +3009,10 @@ static void pfield_draw_line (struct vidbuffer *vb, int lineno, int gfx_ypos, in
                /* The problem is that we must call decode_ham() BEFORE we do the sprites. */
                if (dp_for_drawing->ham_seen) {
                        int ohposblank = hposblank;
-                       uae_u8 b0 = dp_for_drawing->bplcon0;
-                       uae_u8 b2 = dp_for_drawing->bplcon2;
-                       uae_u8 b3 = dp_for_drawing->bplcon3;
-                       uae_u8 b4 = dp_for_drawing->bplcon4;
+                       uae_u16 b0 = dp_for_drawing->bplcon0;
+                       uae_u16 b2 = dp_for_drawing->bplcon2;
+                       uae_u16 b3 = dp_for_drawing->bplcon3;
+                       uae_u16 b4 = dp_for_drawing->bplcon4;
                        init_ham_decoding ();
                        do_color_changes (dummy_worker, decode_ham, lineno);
                        if (have_color_changes) {