# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1493270172 25200
# Node ID 69c25e1188e53ab4f199b97054648c76f0354545
# Parent  87bbc4bec95800cca1a2159985c040552e576b15
Small tweak to how SAT cache updates are done. Mostly fixes the rotating cube scene in Overdrive 2

diff -r 87bbc4bec958 -r 69c25e1188e5 genesis.c
--- a/genesis.c	Wed Apr 26 21:55:12 2017 -0700
+++ b/genesis.c	Wed Apr 26 22:16:12 2017 -0700
@@ -1045,7 +1045,11 @@
 		}
 		for (int i = 0; i < VRAM_SIZE; i++)
 		{
-			write_vram_byte(gen->vdp, i, rand());
+			gen->vdp->vdpmem[i] = rand();
+		}
+		for (int i = 0; i < SAT_CACHE_SIZE; i++)
+		{
+			gen->vdp->sat_cache[i] = rand();
 		}
 		for (int i = 0; i < CRAM_SIZE; i++)
 		{
diff -r 87bbc4bec958 -r 69c25e1188e5 gst.c
--- a/gst.c	Wed Apr 26 21:55:12 2017 -0700
+++ b/gst.c	Wed Apr 26 22:16:12 2017 -0700
@@ -251,7 +251,8 @@
 		return 0;
 	}
 	for (int i = 0; i < VRAM_SIZE; i++) {
-		write_vram_byte(context, i, tmp_buf[i]);
+		context->vdpmem[i] = tmp_buf[i];
+		vdp_check_update_sat_byte(context, i, tmp_buf[i]);
 	}
 	return 1;
 }
diff -r 87bbc4bec958 -r 69c25e1188e5 vdp.c
--- a/vdp.c	Wed Apr 26 21:55:12 2017 -0700
+++ b/vdp.c	Wed Apr 26 22:16:12 2017 -0700
@@ -804,24 +804,22 @@
 	}
 }
 
-void write_vram_word(vdp_context *context, uint32_t address, uint8_t value)
+static void vdp_check_update_sat(vdp_context *context, uint32_t address, uint16_t value)
 {
-	if (!(address & 4)) {
-		uint32_t sat_address = mode5_sat_address(context);
-		if(address >= sat_address && address < (sat_address + SAT_CACHE_SIZE*2)) {
-			uint16_t cache_address = address - sat_address;
-			cache_address = (cache_address & 3) | (cache_address >> 1 & 0x1FC);
-			context->sat_cache[cache_address] = value >> 8;
-			context->sat_cache[cache_address^1] = value;
+	if (context->regs[REG_MODE_2] & BIT_MODE_5) {
+		if (!(address & 4)) {
+			uint32_t sat_address = mode5_sat_address(context);
+			if(address >= sat_address && address < (sat_address + SAT_CACHE_SIZE*2)) {
+				uint16_t cache_address = address - sat_address;
+				cache_address = (cache_address & 3) | (cache_address >> 1 & 0x1FC);
+				context->sat_cache[cache_address] = value >> 8;
+				context->sat_cache[cache_address^1] = value;
+			}
 		}
 	}
-	address = (address & 0x3FC) | (address >> 1 & 0xFC01) | (address >> 9 & 0x2);
-	address ^= 1;
-	//TODO: Support an option to actually have 128KB of VRAM
-	context->vdpmem[address] = value;
 }
 
-void write_vram_byte(vdp_context *context, uint32_t address, uint8_t value)
+void vdp_check_update_sat_byte(vdp_context *context, uint32_t address, uint8_t value)
 {
 	if (context->regs[REG_MODE_2] & BIT_MODE_5) {
 		if (!(address & 4)) {
@@ -832,6 +830,20 @@
 				context->sat_cache[cache_address] = value;
 			}
 		}
+	}
+}
+
+static void write_vram_word(vdp_context *context, uint32_t address, uint16_t value)
+{
+	address = (address & 0x3FC) | (address >> 1 & 0xFC01) | (address >> 9 & 0x2);
+	address ^= 1;
+	//TODO: Support an option to actually have 128KB of VRAM
+	context->vdpmem[address] = value;
+}
+
+static void write_vram_byte(vdp_context *context, uint32_t address, uint8_t value)
+{
+	if (context->regs[REG_MODE_2] & BIT_MODE_5) {
 		address &= 0xFFFF;
 	} else {
 		address = mode4_address_map[address & 0x3FFF];
@@ -854,14 +866,19 @@
 		switch (start->cd & 0xF)
 		{
 		case VRAM_WRITE:
-			//TODO: Support actually having 128K VRAM as an option
 			if ((context->regs[REG_MODE_2] & (BIT_128K_VRAM|BIT_MODE_5)) == (BIT_128K_VRAM|BIT_MODE_5)) {
+				vdp_check_update_sat(context, start->address, start->value);
 				write_vram_word(context, start->address, start->value);
 			} else if (start->partial) {
 				//printf("VRAM Write: %X to %X at %d (line %d, slot %d)\n", start->value, start->address ^ 1, context->cycles, context->cycles/MCLKS_LINE, (context->cycles%MCLKS_LINE)/16);
-				write_vram_byte(context, start->address ^ 1, start->partial == 2 ? start->value >> 8 : start->value);
+				uint8_t byte = start->partial == 2 ? start->value >> 8 : start->value;
+				if (start->partial > 1) {
+					vdp_check_update_sat_byte(context, start->address ^ 1, byte);
+				}
+				write_vram_byte(context, start->address ^ 1, byte);
 			} else {
 				//printf("VRAM Write High: %X to %X at %d (line %d, slot %d)\n", start->value >> 8, start->address, context->cycles, context->cycles/MCLKS_LINE, (context->cycles%MCLKS_LINE)/16);
+				vdp_check_update_sat(context, start->address, start->value);
 				write_vram_byte(context, start->address, start->value >> 8);
 				start->partial = 1;
 				//skip auto-increment and removal of entry from fifo
@@ -870,7 +887,7 @@
 			break;
 		case CRAM_WRITE: {
 			//printf("CRAM Write | %X to %X\n", start->value, (start->address/2) & (CRAM_SIZE-1));
-			if (start->partial == 1) {
+			if (start->partial == 3) {
 				uint16_t val;
 				if ((start->address & 1) && (context->regs[REG_MODE_2] & BIT_MODE_5)) {
 					val = (context->cram[start->address >> 1 & (CRAM_SIZE-1)] & 0xFF) | start->value << 8;
@@ -887,7 +904,7 @@
 		case VSRAM_WRITE:
 			if (((start->address/2) & 63) < VSRAM_SIZE) {
 				//printf("VSRAM Write: %X to %X @ vcounter: %d, hslot: %d, cycle: %d\n", start->value, context->address, context->vcounter, context->hslot, context->cycles);
-				if (start->partial == 1) {
+				if (start->partial == 3) {
 					if (start->address & 1) {
 						context->vsram[(start->address/2) & 63] &= 0xFF;
 						context->vsram[(start->address/2) & 63] |= start->value << 8;
@@ -2744,7 +2761,7 @@
 	} else {
 		cur->cd = (context->cd & 2) | 1;
 	}
-	cur->partial = 1;
+	cur->partial = 3;
 	if (context->fifo_read < 0) {
 		context->fifo_read = context->fifo_write;
 	}
diff -r 87bbc4bec958 -r 69c25e1188e5 vdp.h
--- a/vdp.h	Wed Apr 26 21:55:12 2017 -0700
+++ b/vdp.h	Wed Apr 26 22:16:12 2017 -0700
@@ -239,6 +239,6 @@
 void latch_mode(vdp_context * context);
 uint32_t vdp_cycles_to_frame_end(vdp_context * context);
 void write_cram(vdp_context * context, uint16_t address, uint16_t value);
-void write_vram_byte(vdp_context *context, uint32_t address, uint8_t value);
+void vdp_check_update_sat_byte(vdp_context *context, uint32_t address, uint8_t value);
 
 #endif //VDP_H_