# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1482871417 28800
# Node ID 1913f9c280033865cc28cfcf63c95b74af6ccfab
# Parent  e9369d6f0101c6ca4b163fd7ba77829e80201211
Less broken Mode 4 implementation

diff -r e9369d6f0101 -r 1913f9c28003 vdp.c
--- a/vdp.c	Tue Dec 27 11:31:17 2016 -0800
+++ b/vdp.c	Tue Dec 27 12:43:37 2016 -0800
@@ -1246,9 +1246,9 @@
 			if (context->regs[REG_MODE_1] & BIT_SPRITE_8PX) {
 				sprite_src += 8;
 			}
-			uint8_t *bg_src = context->tmp_buf_a + (((col & 1) * 8 + (context->hscroll_a & 0x7)) & 0x15);
-			for (int i = 0; i < 8; i++, bg_src++, sprite_src++)
+			for (int i = 0; i < 8; i++, sprite_src++)
 			{
+				uint8_t *bg_src = context->tmp_buf_a + ((8 + i + col * 8 - (context->hscroll_a & 0x7)) & 15);
 				if ((*bg_src & 0x4F) > 0x40) {
 					//background plane has priority and is opaque
 					if (context->debug) {
@@ -1895,6 +1895,8 @@
 	case 253:
 		external_slot(context);
 		scan_sprite_table_mode4(context->vcounter, context);//Just a guess
+		context->buf_a_off = 8;
+		memset(context->tmp_buf_a, 0, 8);
 		//reverse context slot counter so it counts the number of sprite slots
 		//filled rather than the number of available slots
 		//context->slot_counter = MAX_SPRITES_LINE - context->slot_counter;