games/md: vdp window fix, added ym2612 timers

4 files changed, 42 insertions, 4 deletions

diff --git a/sys/src/games/md/dat.h b/sys/src/games/md/dat.h
index 3df16bb2c..33467024e 100644
--- a/sys/src/games/md/dat.h
+++ b/sys/src/games/md/dat.h
@@ -22,7 +22,7 @@ extern u32int cramc[64];
 extern u16int vdpstat;
 extern int vdpx, vdpy;
 
-extern u8int ym[512];
+extern u8int ym[512], ymstat;
 
 enum {
 	MODE1   = 0x00,
diff --git a/sys/src/games/md/mem.c b/sys/src/games/md/mem.c
index e874d7f24..a1474934e 100644
--- a/sys/src/games/md/mem.c
+++ b/sys/src/games/md/mem.c
@@ -328,7 +328,7 @@ z80read(u16int a)
 	case 1:
 		return zram[a & 0x1fff];
 	case 2:
-		return 0;
+		return ymstat;
 	case 3:
 		if(a >= 0x7f00){
 			v = memread(0xc00000 | a & 0x7e);
diff --git a/sys/src/games/md/vdp.c b/sys/src/games/md/vdp.c
index 8230a8cdd..a16f08841 100644
--- a/sys/src/games/md/vdp.c
+++ b/sys/src/games/md/vdp.c
@@ -144,7 +144,8 @@ planeinit(void)
 	}
 	if(rwin > lwin){
 		p = pctxt + 2;
-		p->tx = p->ty = 0;
+		p->tx = lwin >> 3 & pctxt[2].w - 1;
+		p->tnx = lwin & 7;
 		p->tny = vdpy & 7;
 		p->ty = vdpy >> 3 & pctxt[2].h - 1;
 		tile(p);
@@ -306,7 +307,10 @@ vdpstep(void)
 			pri = 0;
 			planes();
 			sprites();
-			pixeldraw(vdpx, vdpy, cramc[col]);
+			if((reg[MODE2] & 0x40) != 0 && (vdpx >= 8 || (reg[MODE1] & 0x20) == 0))
+				pixeldraw(vdpx, vdpy, cramc[col]);
+			else
+				pixeldraw(vdpx, vdpy, 0);
 		}else
 			pixeldraw(vdpx, vdpy, 0xcccccc);
 	if(++vdpx >= xmax){
diff --git a/sys/src/games/md/ym.c b/sys/src/games/md/ym.c
index 835c1881d..16389a693 100644
--- a/sys/src/games/md/ym.c
+++ b/sys/src/games/md/ym.c
@@ -35,13 +35,42 @@ struct fm {
 	u8int st, alg, en, fbs;
 	float samp;
 } fms[6];
+u8int ymstat;
 static u32int cyc;
+static u16int tima;
+static u8int timb;
 
 static short sbuf[2 * 2000], *sbufp;
 static int fd;
 static int sint[256], expt[256];
 
 static void
+timers(void)
+{
+	u8int m;
+	static u8int bdiv;
+
+	m = ym[0x27];
+	if((m & 1) != 0){
+		tima = (tima + 1) & 0x3ff;
+		if(tima == 0 && (m & 4) != 0){
+			ymstat |= 2;
+			tima = ym[0x24] | ym[0x25] << 8 & 0x300;
+		}
+	}
+	if(++bdiv == 8){
+		bdiv = 0;
+		if((m & 2) != 0){
+			timb++;
+			if(timb == 0 && (m & 8) != 0){
+				ymstat |= 1;
+				timb = ym[0x26];
+			}
+		}
+	}
+}
+
+static void
 calcfreq(int n)
 {
 	int i, fr;
@@ -129,6 +158,10 @@ ymwrite(u8int a, u8int v, u8int c)
 		ch = c + (a & 3);
 		switch(a){
 		case MODE:
+			if((v & 0x10) != 0)
+				ymstat &= ~2;
+			if((v & 0x20) != 0)
+				ymstat &= ~1;
 			calcfreq(2);
 			calcfreq(5);
 			break;
@@ -359,6 +392,7 @@ ymstep(void)
 			if(++ymcyc == 3){
 				cyc++;
 				ymcyc = 0;
+				timers();
 			}
 		}
 		ymop = 0;