Shift slot number to slot behavior mapping by six slots in H40 mode. This makes the line change slot align with the point at which the display turns on and off at the end of the active display area. Also fixed a regression in which an external slot got accidentally changed into a sprite draw slot

2 files changed, 88 insertions, 106 deletions

diff --git a/vdp.c b/vdp.c
index b064b10..c2512e0 100644
--- a/vdp.c
+++ b/vdp.c
@@ -24,7 +24,7 @@
 #define MCLKS_SLOT_H32  20
 #define VINT_SLOT_H40  4 //21 slots before HSYNC, 16 during, 10 after
 #define VINT_SLOT_H32  4  //old value was 23, but recent tests suggest the actual value is close to the H40 one
-#define HSYNC_SLOT_H40  234
+#define HSYNC_SLOT_H40  228
 #define HSYNC_END_H40  (HSYNC_SLOT_H40+17)
 #define HSYNC_END_H32   (33 * MCLKS_SLOT_H32)
 #define HBLANK_START_H40 178 //should be 179 according to Nemesis, but 178 seems to fit slightly better with my test ROM results
@@ -981,25 +981,25 @@ void vdp_advance_line(vdp_context *context)
 	case startcyc:\
 		read_map_scroll_a(column, context->vcounter, context);\
 		CHECK_LIMIT\
-	case (startcyc+1):\
+	case ((startcyc+1)&0xFF):\
 		external_slot(context);\
 		CHECK_LIMIT\
-	case (startcyc+2):\
+	case ((startcyc+2)&0xFF):\
 		render_map_1(context);\
 		CHECK_LIMIT\
-	case (startcyc+3):\
+	case ((startcyc+3)&0xFF):\
 		render_map_2(context);\
 		CHECK_LIMIT\
-	case (startcyc+4):\
+	case ((startcyc+4)&0xFF):\
 		read_map_scroll_b(column, context->vcounter, context);\
 		CHECK_LIMIT\
-	case (startcyc+5):\
+	case ((startcyc+5)&0xFF):\
 		read_sprite_x(context->vcounter, context);\
 		CHECK_LIMIT\
-	case (startcyc+6):\
+	case ((startcyc+6)&0xFF):\
 		render_map_3(context);\
 		CHECK_LIMIT\
-	case (startcyc+7):\
+	case ((startcyc+7)&0xFF):\
 		render_map_output(context->vcounter, column, context);\
 		CHECK_LIMIT
 
@@ -1029,7 +1029,7 @@ void vdp_advance_line(vdp_context *context)
 		CHECK_LIMIT\
 	case (startcyc+7):\
 		render_map_output(context->vcounter, column, context);\
-		if (column == 40 || (column == 32 && startcyc == 124)) {\
+		if (column == 32 && startcyc == 124) {\
 			vdp_advance_line(context);\
 		}\
 		CHECK_LIMIT
@@ -1041,7 +1041,7 @@ void vdp_advance_line(vdp_context *context)
 		if (context->flags & FLAG_DMA_RUN) { run_dma_src(context, context->hslot); } \
 		if (slot == 182) {\
 			context->hslot = 229;\
-			context->cycles += slot_cycles;\
+			context->cycles += h40_hsync_cycles[0];\
 		} else {\
 			context->hslot++;\
 			if (slot >= HSYNC_SLOT_H40 && slot < HSYNC_END_H40) {\
@@ -1075,55 +1075,21 @@ void vdp_h40(vdp_context * context, uint32_t target_cycles)
 	{
 	for (;;)
 	{
-	case 165:
-		external_slot(context);
-		CHECK_LIMIT
-	case 166:
-		external_slot(context);
-		CHECK_LIMIT
-	//sprite render to line buffer starts
-	case 167:
-		context->cur_slot = MAX_DRAWS-1;
-		memset(context->linebuf, 0, LINEBUF_SIZE);
-		if (context->vcounter == 0x1FF) {
-			external_slot(context);
-		} else {
-			render_sprite_cells(context);
-		}
-		CHECK_LIMIT
-	case 168:
-		if (context->vcounter == 0x1FF) {
-			external_slot(context);
-		} else {
-			render_sprite_cells(context);
-		}
-		CHECK_LIMIT
-	case 169:
-		if (context->vcounter == 0x1FF) {
-			external_slot(context);
-		} else {
-			render_sprite_cells(context);
-		}
-		CHECK_LIMIT
-	case 170:
-		if (context->vcounter == 0x1FF) {
-			external_slot(context);
-		} else {
-			render_sprite_cells(context);
-			if (context->vcounter == (context->latched_mode & BIT_PAL ? PAL_INACTIVE_START : NTSC_INACTIVE_START)) {
-				context->hslot++;
-				context->cycles += slot_cycles;
-				return;
-			}
-		}
-		CHECK_LIMIT
 	//sprite attribute table scan starts
-	case 171:
+	case 165:
 		context->sprite_index = 0x80;
 		context->slot_counter = MAX_SPRITES_LINE;
 		render_sprite_cells( context);
 		scan_sprite_table(context->vcounter, context);
 		CHECK_LIMIT
+	SPRITE_RENDER_H40(166)
+	SPRITE_RENDER_H40(167)
+	case 168:
+		external_slot(context);
+		CHECK_LIMIT
+	SPRITE_RENDER_H40(169)
+	SPRITE_RENDER_H40(170)
+	SPRITE_RENDER_H40(171)
 	SPRITE_RENDER_H40(172)
 	SPRITE_RENDER_H40(173)
 	SPRITE_RENDER_H40(174)
@@ -1134,13 +1100,13 @@ void vdp_h40(vdp_context * context, uint32_t target_cycles)
 	SPRITE_RENDER_H40(179)
 	SPRITE_RENDER_H40(180)
 	SPRITE_RENDER_H40(181)
+	//!HSYNC asserted
 	SPRITE_RENDER_H40(182)
 	SPRITE_RENDER_H40(229)
 	SPRITE_RENDER_H40(230)
 	SPRITE_RENDER_H40(231)
 	SPRITE_RENDER_H40(232)
 	SPRITE_RENDER_H40(233)
-	//!HSYNC asserted
 	SPRITE_RENDER_H40(234)
 	SPRITE_RENDER_H40(235)
 	SPRITE_RENDER_H40(236)
@@ -1149,13 +1115,7 @@ void vdp_h40(vdp_context * context, uint32_t target_cycles)
 	SPRITE_RENDER_H40(239)
 	SPRITE_RENDER_H40(240)
 	SPRITE_RENDER_H40(241)
-	SPRITE_RENDER_H40(242)
-	SPRITE_RENDER_H40(243)
-	SPRITE_RENDER_H40(244)
-	SPRITE_RENDER_H40(245)
-	SPRITE_RENDER_H40(246)
-	SPRITE_RENDER_H40(247)
-	case 248:
+	case 242:
 		address = (context->regs[REG_HSCROLL] & 0x3F) << 10;
 		mask = 0;
 		if (context->regs[REG_MODE_3] & 0x2) {
@@ -1173,34 +1133,32 @@ void vdp_h40(vdp_context * context, uint32_t target_cycles)
 		context->cycles += h40_hsync_cycles[14];
 		CHECK_ONLY
 	//!HSYNC high
-	SPRITE_RENDER_H40(249)
-	SPRITE_RENDER_H40(250)
-	SPRITE_RENDER_H40(251)
-	SPRITE_RENDER_H40(252)
-	case 253:
+	SPRITE_RENDER_H40(243)
+	SPRITE_RENDER_H40(244)
+	SPRITE_RENDER_H40(245)
+	SPRITE_RENDER_H40(246)
+	case 247:
 		read_map_scroll_a(0, context->vcounter, context);
 		CHECK_LIMIT
-	SPRITE_RENDER_H40(254)
-	case 255:
+	SPRITE_RENDER_H40(248)
+	case 249:
 		render_map_1(context);
 		scan_sprite_table(context->vcounter, context);//Just a guess
 		if (context->flags & FLAG_DMA_RUN) { run_dma_src(context, context->hslot); }
-		context->hslot = 0;
-		context->cycles += slot_cycles;
-		CHECK_ONLY
-	case 0:
+		CHECK_LIMIT
+	case 250:
 		render_map_2(context);
 		scan_sprite_table(context->vcounter, context);//Just a guess
 		CHECK_LIMIT
-	case 1:
+	case 251:
 		read_map_scroll_b(0, context->vcounter, context);
 		CHECK_LIMIT
-	SPRITE_RENDER_H40(2)
-	case 3:
+	SPRITE_RENDER_H40(252)
+	case 253:
 		render_map_3(context);
 		scan_sprite_table(context->vcounter, context);//Just a guess
 		CHECK_LIMIT
-	case 4:
+	case 254:
 		if (context->vcounter == (context->latched_mode & BIT_PAL ? PAL_INACTIVE_START : NTSC_INACTIVE_START)) {
 			context->flags2 |= FLAG2_VINT_PENDING;
 			context->pending_vint_start = context->cycles;
@@ -1214,26 +1172,53 @@ void vdp_h40(vdp_context * context, uint32_t target_cycles)
 		context->sprite_draws = MAX_DRAWS;
 		context->flags &= (~FLAG_CAN_MASK & ~FLAG_MASKED);
 		CHECK_LIMIT
-	COLUMN_RENDER_BLOCK(2, 5)
-	COLUMN_RENDER_BLOCK(4, 13)
-	COLUMN_RENDER_BLOCK(6, 21)
-	COLUMN_RENDER_BLOCK_REFRESH(8, 29)
-	COLUMN_RENDER_BLOCK(10, 37)
-	COLUMN_RENDER_BLOCK(12, 45)
-	COLUMN_RENDER_BLOCK(14, 53)
-	COLUMN_RENDER_BLOCK_REFRESH(16, 61)
-	COLUMN_RENDER_BLOCK(18, 69)
-	COLUMN_RENDER_BLOCK(20, 77)
-	COLUMN_RENDER_BLOCK(22, 85)
-	COLUMN_RENDER_BLOCK_REFRESH(24, 93)
-	COLUMN_RENDER_BLOCK(26, 101)
-	COLUMN_RENDER_BLOCK(28, 109)
-	COLUMN_RENDER_BLOCK(30, 117)
-	COLUMN_RENDER_BLOCK_REFRESH(32, 125)
-	COLUMN_RENDER_BLOCK(34, 133)
-	COLUMN_RENDER_BLOCK(36, 141)
-	COLUMN_RENDER_BLOCK(38, 149)
-	COLUMN_RENDER_BLOCK_REFRESH(40, 157)
+	COLUMN_RENDER_BLOCK(2, 255)
+	COLUMN_RENDER_BLOCK(4, 7)
+	COLUMN_RENDER_BLOCK(6, 15)
+	COLUMN_RENDER_BLOCK_REFRESH(8, 23)
+	COLUMN_RENDER_BLOCK(10, 31)
+	COLUMN_RENDER_BLOCK(12, 39)
+	COLUMN_RENDER_BLOCK(14, 47)
+	COLUMN_RENDER_BLOCK_REFRESH(16, 55)
+	COLUMN_RENDER_BLOCK(18, 63)
+	COLUMN_RENDER_BLOCK(20, 71)
+	COLUMN_RENDER_BLOCK(22, 79)
+	COLUMN_RENDER_BLOCK_REFRESH(24, 87)
+	COLUMN_RENDER_BLOCK(26, 95)
+	COLUMN_RENDER_BLOCK(28, 103)
+	COLUMN_RENDER_BLOCK(30, 111)
+	COLUMN_RENDER_BLOCK_REFRESH(32, 119)
+	COLUMN_RENDER_BLOCK(34, 127)
+	COLUMN_RENDER_BLOCK(36, 135)
+	COLUMN_RENDER_BLOCK(38, 143)
+	COLUMN_RENDER_BLOCK_REFRESH(40, 151)
+	case 159:
+		external_slot(context);
+		CHECK_LIMIT
+	case 160:
+		external_slot(context);
+		CHECK_LIMIT
+	//sprite render to line buffer starts
+	case 161:
+		context->cur_slot = MAX_DRAWS-1;
+		memset(context->linebuf, 0, LINEBUF_SIZE);
+		render_sprite_cells(context);
+		CHECK_LIMIT
+	case 162:
+		render_sprite_cells(context);
+		CHECK_LIMIT
+	case 163:
+		render_sprite_cells(context);
+		CHECK_LIMIT
+	case 164:
+		render_sprite_cells(context);
+		vdp_advance_line(context);
+		if (context->vcounter == (context->latched_mode & BIT_PAL ? PAL_INACTIVE_START : NTSC_INACTIVE_START)) {
+			context->hslot++;
+			context->cycles += slot_cycles;
+			return;
+		}
+		CHECK_LIMIT
 	}
 	default:
 		context->hslot++;
@@ -1445,12 +1430,7 @@ void vdp_run_context(vdp_context * context, uint32_t target_cycles)
 		uint8_t active_slot = context->vcounter < inactive_start || context->vcounter == 0x1FF;
 		uint8_t is_h40 = context->regs[REG_MODE_4] & BIT_H40;
 		if (context->vcounter == inactive_start) {
-			if (is_h40) {
-				//the first inactive line behaves as an active one for the first 4 slots
-				if (context->hslot > LINE_CHANGE_H40 && context->hslot < 171) {
-					active_slot = 1;
-				}
-			} else {
+			if (!is_h40) {
 				//the first inactive line behaves as an active one for the first few slots
 				if (context->hslot > LINE_CHANGE_H32 && context->hslot < 138) {
 					active_slot = 1;
@@ -1465,10 +1445,10 @@ void vdp_run_context(vdp_context * context, uint32_t target_cycles)
 			}
 		} else {
 			if (is_h40) {
-				if (context->hslot == 167) {
+				if (context->hslot == 161) {
 					context->cur_slot = MAX_DRAWS-1;
 					memset(context->linebuf, 0, LINEBUF_SIZE);
-				} else if (context->hslot == 171) {
+				} else if (context->hslot == 165) {
 					context->sprite_index = 0x80;
 					context->slot_counter = MAX_SPRITES_LINE;
 				}
@@ -1490,7 +1470,9 @@ void vdp_run_context(vdp_context * context, uint32_t target_cycles)
 			}
 			uint32_t inccycles;
 			if (is_h40) {
-				if (context->hslot < HSYNC_SLOT_H40 || context->hslot >= HSYNC_END_H40) {
+				if (context->hslot == 182) {
+					inccycles = h40_hsync_cycles[0];
+				} else if (context->hslot < HSYNC_SLOT_H40 || context->hslot >= HSYNC_END_H40) {
 					inccycles = MCLKS_SLOT_H40;
 				} else {
 					inccycles = h40_hsync_cycles[context->hslot-HSYNC_SLOT_H40];
diff --git a/vdp.h b/vdp.h
index 5b9288c..1e0de91 100644
--- a/vdp.h
+++ b/vdp.h
@@ -148,9 +148,9 @@ typedef struct {
 	uint16_t    vscroll_latch[2];
 	uint32_t    frame;
 	uint16_t    vcounter;
-	uint16_t    hslot; //hcounter/2
 	uint16_t    hscroll_a;
 	uint16_t    hscroll_b;
+	uint8_t     hslot; //hcounter/2
 	uint8_t     latched_mode;
 	uint8_t	    sprite_index;
 	uint8_t     sprite_draws;