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diff vdp.c @ 981:902c53d9c16f

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Half assed, prefetch based open bus value emulation. Gets BlastEm up to 119/122 in VDP FIFO Testing
author Michael Pavone <pavone@retrodev.com>
date Sun, 24 Apr 2016 02:19:48 -0700
parents 928442068afe
children 14d2f3b0e45d
line wrap: on
line diff
--- a/vdp.c	Sun Apr 24 01:24:38 2016 -0700
+++ b/vdp.c	Sun Apr 24 02:19:48 2016 -0700
@@ -1694,9 +1694,8 @@
 uint16_t vdp_control_port_read(vdp_context * context)
 {
 	context->flags &= ~FLAG_PENDING;
-	//TODO: Open bus emulation
 	//Bits 15-10 are not fixed like Charles MacDonald's doc suggests, but instead open bus values that reflect 68K prefetch
-	uint16_t value = 0;
+	uint16_t value = get_open_bus_value() & 0xFC00;
 	if (context->fifo_read < 0) {
 		value |= 0x200;
 	}