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changeset 23:a085f17b79e9

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Implement hflip
author Michael Pavone <pavone@retrodev.com>
date Wed, 30 Mar 2016 20:31:04 -0700
parents 407725d9a02f
children 4c9dbfa30a66
files src/vdp.c src/vdp.h
diffstat 2 files changed, 13 insertions(+), 8 deletions(-) [+]
line wrap: on
line diff
--- a/src/vdp.c	Wed Mar 30 19:55:48 2016 -0700
+++ b/src/vdp.c	Wed Mar 30 20:31:04 2016 -0700
@@ -48,10 +48,11 @@
 				if (context->draw_counter) {
 					context->draw_counter--;
 					uint16_t pixels = context->vram[context->draw_source++];
-					for (int i = 0; i < 4; i++)
+					for (int i = context->hflip ? 0 : 12; i >= 0 && i < 16; i+= context->hflip ? 4 : -4)
 					{
-						uint8_t pixel = ((pixels >> ((3-i) * 4)) & 0xF) | context->palpriority;
-						context->drawbuffer[context->draw_dest++] = pixel;
+						uint8_t pixel = ((pixels >> i) & 0xF) | context->palpriority;
+						context->drawbuffer[context->draw_dest ^ (context->hflip << 2)] = pixel;
+						context->draw_dest++;
 					}
 				} else {
 					//00VV VVVV VVHH HHHH
@@ -71,7 +72,7 @@
 					}
 					context->palpriority = entry >> 9 & 0x70;
 					context->draw_counter = 2;
-					//TODO: handle horizontal flip
+					context->hflip = (entry & 0x800) != 0;
 				}
 				if (context->status & VDP_STATUS_SPRITE_SCAN) {
 					context->status |= VDP_STATUS_SRAM;
@@ -99,6 +100,10 @@
 								context->sprite_draws[context->current_draw].x = x + 8;
 								context->sprite_draws[context->current_draw].hflip = (atts & 0x800) != 0;
 								context->sprite_draws[context->current_draw].palpriority = 0x80 | (atts >> 9 & 0x50);
+								if (context->sprite_draws[context->current_draw].hflip) {
+									context->sprite_draws[context->current_draw].x -= 8;
+									context->sprite_draws[context->current_draw-1].x += 8;
+								}
 							}
 							context->current_draw++;
 							if (context->current_draw == 40) {
@@ -119,12 +124,11 @@
 					context->status |= VDP_STATUS_VRAM;
 					uint16_t pixels = context->vram[draw->source + (context->current_draw & 1)];
 					uint16_t x = draw->x - 16 + (context->hscroll & 7);
-					for (int i = 0; i < 4; i++, x++)
+					for (int i = draw->hflip ? 0 : 12; i >= 0 && i < 16; i+= draw->hflip ? 4 : -4, x++)
 					{
-						//TODO: handle horizontal flip
-						uint8_t pixel = (pixels >> ((3-i) * 4)) & 0xF;
+						uint8_t pixel = (pixels >> i) & 0xF;
 						if (pixel && x < 328 && ((draw->palpriority & 0x40) || !(context->drawbuffer[x] & 0x40))) {
-							context->drawbuffer[x] = pixel | draw->palpriority;
+							context->drawbuffer[x ^ (draw->hflip << 2)] = pixel | draw->palpriority;
 						}
 					}
 					if (context->current_draw & 1) {
--- a/src/vdp.h	Wed Mar 30 19:55:48 2016 -0700
+++ b/src/vdp.h	Wed Mar 30 20:31:04 2016 -0700
@@ -39,6 +39,7 @@
 	
 	uint8_t  fifo_dest;
 	uint8_t  draw_counter;
+	uint8_t  hflip;
 	uint8_t  palpriority;
 	uint8_t  current_draw;
 } vdp;