Implemented Mode 4 H conter latching

3 files changed, 46 insertions, 18 deletions

diff --git a/sms.c b/sms.c
index 170f2ce..b74b6dd 100644
--- a/sms.c
+++ b/sms.c
@@ -12,8 +12,19 @@ static void *memory_io_write(uint32_t location, void *vcontext, uint8_t value)
 	z80_context *z80 = vcontext;
 	sms_context *sms = z80->system;
 	if (location & 1) {
+		uint8_t fuzzy_ctrl_0 = sms->io.ports[0].control, fuzzy_ctrl_1 = sms->io.ports[1].control;
 		sms->io.ports[0].control = (~value) << 5 & 0x60;
+		fuzzy_ctrl_0 |= sms->io.ports[0].control;
 		sms->io.ports[1].control = (~value) << 3 & 0x60;
+		fuzzy_ctrl_1 |= sms->io.ports[1].control;
+		if (
+			(fuzzy_ctrl_0 & 0x40 & (sms->io.ports[0].output ^ (value << 1)) & (value << 1))
+			|| (fuzzy_ctrl_0 & 0x40 & (sms->io.ports[1].output ^ (value >> 1)) & (value >> 1))
+		) {
+			//TH is an output and it went from 0 -> 1
+			vdp_run_context(sms->vdp, z80->current_cycle);
+			vdp_latch_hv(sms->vdp);
+		}
 		io_data_write(sms->io.ports, value << 1, z80->current_cycle);
 		io_data_write(sms->io.ports + 1, value >> 1, z80->current_cycle);
 	} else {
diff --git a/vdp.c b/vdp.c
index ae0f7ba..af04a05 100644
--- a/vdp.c
+++ b/vdp.c
@@ -2140,6 +2140,39 @@ void vdp_run_dma_done(vdp_context * context, uint32_t target_cycles)
 	}
 }
 
+static uint16_t get_ext_vcounter(vdp_context *context)
+{
+	uint16_t line= context->vcounter & 0xFF;
+	if (context->double_res) {
+		line <<= 1;
+		if (line & 0x100) {
+			line |= 1;
+		}
+	}
+	return line << 8;
+}
+
+void vdp_latch_hv(vdp_context *context)
+{
+	context->hv_latch = context->hslot | get_ext_vcounter(context);
+}
+
+uint16_t vdp_hv_counter_read(vdp_context * context)
+{
+	if ((context->regs[REG_MODE_2] & BIT_MODE_5) && (context->regs[REG_MODE_1] & BIT_HVC_LATCH)) {
+		return context->hv_latch;
+	}
+	uint16_t hv;
+	if (context->regs[REG_MODE_2] & BIT_MODE_5) {
+		hv = context->hslot;
+	} else {
+		hv = context->hv_latch & 0xFF;
+	}
+	hv |= get_ext_vcounter(context);
+	
+	return hv;
+}
+
 int vdp_control_port_write(vdp_context * context, uint16_t value)
 {
 	//printf("control port write: %X at %d\n", value, context->cycles);
@@ -2184,7 +2217,7 @@ int vdp_control_port_write(vdp_context * context, uint16_t value)
 			if (reg < (mode_5 ? VDP_REGS : 0xB)) {
 				//printf("register %d set to %X\n", reg, value & 0xFF);
 				if (reg == REG_MODE_1 && (value & BIT_HVC_LATCH) && !(context->regs[reg] & BIT_HVC_LATCH)) {
-					context->hv_latch = vdp_hv_counter_read(context);
+					vdp_latch_hv(context);
 				}
 				if (reg == REG_BG_COLOR) {
 					value &= 0x3F;
@@ -2388,23 +2421,6 @@ uint8_t vdp_data_port_read_pbc(vdp_context * context)
 	return context->prefetch;
 }
 
-uint16_t vdp_hv_counter_read(vdp_context * context)
-{
-	if ((context->regs[REG_MODE_2] & BIT_MODE_5) && (context->regs[REG_MODE_1] & BIT_HVC_LATCH)) {
-		return context->hv_latch;
-	}
-	uint32_t line= context->vcounter & 0xFF;
-	uint32_t linecyc = context->hslot;
-	linecyc &= 0xFF;
-	if (context->double_res) {
-		line <<= 1;
-		if (line & 0x100) {
-			line |= 1;
-		}
-	}
-	return (line << 8) | linecyc;
-}
-
 uint16_t vdp_test_port_read(vdp_context * context)
 {
 	//TODO: Find out what actually gets returned here
diff --git a/vdp.h b/vdp.h
index 59944b5..76fee6e 100644
--- a/vdp.h
+++ b/vdp.h
@@ -213,6 +213,7 @@ void vdp_test_port_write(vdp_context * context, uint16_t value);
 uint16_t vdp_control_port_read(vdp_context * context);
 uint16_t vdp_data_port_read(vdp_context * context);
 uint8_t vdp_data_port_read_pbc(vdp_context * context);
+void vdp_latch_hv(vdp_context *context);
 uint16_t vdp_hv_counter_read(vdp_context * context);
 uint16_t vdp_test_port_read(vdp_context * context);
 void vdp_adjust_cycles(vdp_context * context, uint32_t deduction);