core vdp, implement partial line blanking

pico/draw.c

@@ -1987,7 +1987,7 @@ static void DrawBlankedLine(int line, int offs, int sh, int bgc)
   est->DrawLineDest = (char *)est->DrawLineDest + DrawLineDestIncrement;
 }
 
-static void PicoLine(int line, int offs, int sh, int bgc)
+static void PicoLine(int line, int offs, int sh, int bgc, int off, int on)
 {
   struct PicoEState *est = &Pico.est;
   int skip = skip_next_line;
@@ -2006,8 +2006,17 @@ static void PicoLine(int line, int offs, int sh, int bgc)
 
   // Draw screen:
   BackFill(bgc, sh, est);
-  if (Pico.video.reg[1]&0x40)
+  if (Pico.video.reg[1]&0x40) {
+    int width = (Pico.video.reg[12]&1) ? 320 : 256;
     DrawDisplay(sh);
+    // partial line blanking (display on or off inside the line)
+    if (unlikely(off|on)) {
+      if (off > 0)
+        memset(est->HighCol+8 + off, bgc, width-off);
+      if (on > 0)
+        memset(est->HighCol+8, bgc, on);
+    }
+  }
 
   if (FinalizeLine != NULL)
     FinalizeLine(sh, line, est);
@@ -2019,7 +2028,7 @@ static void PicoLine(int line, int offs, int sh, int bgc)
   est->DrawLineDest = (char *)est->DrawLineDest + DrawLineDestIncrement;
 }
 
-void PicoDrawSync(int to, int blank_last_line, int limit_sprites)
+void PicoDrawSync(int to, int off, int on)
 {
   struct PicoEState *est = &Pico.est;
   int line, offs = 0;
@@ -2035,7 +2044,7 @@ void PicoDrawSync(int to, int blank_last_line, int limit_sprites)
   }
   if (est->DrawScanline <= to &&
                 (est->rendstatus & (PDRAW_DIRTY_SPRITES|PDRAW_PARSE_SPRITES)))
-    ParseSprites(to + 1, limit_sprites);
+    ParseSprites(to + 1, on);
   else if (!(est->rendstatus & PDRAW_SYNC_NEEDED)) {
     // nothing has changed in VDP/VRAM and buffer is the same -> no sync needed
     int count = to+1 - est->DrawScanline;
@@ -2046,14 +2055,22 @@ void PicoDrawSync(int to, int blank_last_line, int limit_sprites)
   }
 
   for (line = est->DrawScanline; line < to; line++)
-    PicoLine(line, offs, sh, bgc);
+    PicoLine(line, offs, sh, bgc, 0, 0);
 
   // last line
   if (line <= to)
   {
-    if (blank_last_line)
+    int width2 = (Pico.video.reg[12]&1) ? 160 : 128;
+
+    // technically, VDP starts active display output at slot 12
+    if (unlikely(on|off) && (off >= width2 ||
+          // hack for timing inaccuracy, if on/off near borders
+          (off && off <= 24) || (on < width2 && on >= width2-24)))
       DrawBlankedLine(line, offs, sh, bgc);
-    else PicoLine(line, offs, sh, bgc);
+    else {
+      if (on > width2) on = 0; // on, before start of line?
+      PicoLine(line, offs, sh, bgc, 2*off, 2*on);
+    }
     line++;
   }
   est->DrawScanline = line;

pico/videoport.c

@@ -138,8 +138,9 @@ void PicoVideoInit(void)
 }
 
 
-static int blankline;           // display disabled for this line
+static int linedisabled;    // display disabled on this line
-static int limitsprites;
+static int lineenabled;     // display enabled on this line
+static int lineoffset;      // offset at which dis/enable took place
 
 u32 SATaddr, SATmask;       // VRAM addr of sprite attribute table
 
@@ -811,8 +812,9 @@ static inline int InHblank(int offs)
 
 void PicoVideoSync(int skip)
 {
+  struct VdpFIFO *vf = &VdpFIFO;
   int lines = Pico.video.reg[1]&0x08 ? 240 : 224;
-  int last = Pico.m.scanline - ((skip > 0) || blankline == Pico.m.scanline);
+  int last = Pico.m.scanline - (skip > 0);
 
   if (!(PicoIn.opt & POPT_ALT_RENDERER) && !PicoIn.skipFrame) {
     if (last >= lines)
@@ -821,13 +823,22 @@ void PicoVideoSync(int skip)
       Pico.est.rendstatus |= PDRAW_SYNC_NEXT;
 
     //elprintf(EL_ANOMALY, "sync");
-    if (blankline >= 0 && blankline < last) {
+    if (unlikely(linedisabled >= 0 && linedisabled <= last)) {
-      PicoDrawSync(blankline, 1, 0);
+      if (Pico.est.DrawScanline <= linedisabled) {
-      blankline = -1;
+        int sl = vf->fifo_hcounts[lineoffset/clkdiv];
+        PicoDrawSync(linedisabled, sl ? sl : 1, 0);
       }
-    PicoDrawSync(last, 0, last == limitsprites);
+      linedisabled = -1;
-    if (last >= limitsprites)
+    }
-      limitsprites = -1;
+    if (unlikely(lineenabled >= 0 && lineenabled <= last)) {
+      if (Pico.est.DrawScanline <= lineenabled) {
+        int sl = vf->fifo_hcounts[lineoffset/clkdiv];
+        PicoDrawSync(lineenabled, 0, sl ? sl : 1);
+      }
+      lineenabled = -1;
+    }
+    if (Pico.est.DrawScanline <= last)
+      PicoDrawSync(last, 0, 0);
   }
   if (skip >= 0)
     Pico.est.rendstatus |= PDRAW_SYNC_NEEDED;
@@ -911,19 +922,18 @@ PICO_INTERNAL_ASM void PicoVideoWrite(u32 a,unsigned short d)
         d &= 0xff;
         if (num == 0 && !(pvid->reg[0]&2) && (d&2))
           pvid->hv_latch = PicoVideoRead(0x08);
-        if (num == 1 && ((pvid->reg[1]^d)&0x40)) {
-          PicoVideoFIFOMode(d & 0x40, pvid->reg[12]&1);
-          // handle line blanking before line rendering
-          if (InHblank(93)) {
-            // sprite rendering is limited if display is disabled and reenabled
-            // in HBLANK of the same scanline (Overdrive)
-            limitsprites = (d&0x40) && blankline == Pico.m.scanline ? Pico.m.scanline : -1;
-            blankline = (d&0x40) ? -1 : Pico.m.scanline;
-          }
-        }
         if (num == 12 && ((pvid->reg[12]^d)&0x01))
           PicoVideoFIFOMode(pvid->reg[1]&0x40, d & 1);
-        if (((1<<num) & 0x738ff) && pvid->reg[num] != d)
+
+        if (num == 1 && ((pvid->reg[1]^d)&0x40)) {
+          PicoVideoFIFOMode(d & 0x40, pvid->reg[12]&1);
+          // handle line blanking before line rendering. Only the last switch
+          // before the 1st sync for other reasons is honoured.
+          PicoVideoSync(1);
+          lineenabled = (d&0x40) ? Pico.m.scanline : -1;
+          linedisabled = (d&0x40) ? -1 : Pico.m.scanline;
+          lineoffset = SekCyclesDone() - Pico.t.m68c_line_start;
+	} else if (((1<<num) & 0x738ff) && pvid->reg[num] != d)
           // VDP regs 0-7,11-13,16-18 influence rendering, ignore all others
           PicoVideoSync(InHblank(93)); // Toy Story
         pvid->reg[num] = d;