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Properly emulate machine freeze when reading from VDP while configured for writes
author Michael Pavone <pavone@retrodev.com>
date Wed, 27 Apr 2016 23:57:00 -0700
parents bd4d698d995b
children 2bc27415565b
comparison
equal deleted inserted replaced
990:33a46d35b913 991:f9ee6f746cb4
6 #include "vdp.h" 6 #include "vdp.h"
7 #include "blastem.h" 7 #include "blastem.h"
8 #include <stdlib.h> 8 #include <stdlib.h>
9 #include <string.h> 9 #include <string.h>
10 #include "render.h" 10 #include "render.h"
11 #include "util.h"
11 12
12 #define NTSC_INACTIVE_START 224 13 #define NTSC_INACTIVE_START 224
13 #define PAL_INACTIVE_START 240 14 #define PAL_INACTIVE_START 240
14 #define BUF_BIT_PRIORITY 0x40 15 #define BUF_BIT_PRIORITY 0x40
15 #define MAP_BIT_PRIORITY 0x8000 16 #define MAP_BIT_PRIORITY 0x8000
1735 //Should these be cleared here? 1736 //Should these be cleared here?
1736 context->flags &= ~FLAG_READ_FETCHED; 1737 context->flags &= ~FLAG_READ_FETCHED;
1737 context->flags2 &= ~FLAG2_READ_PENDING; 1738 context->flags2 &= ~FLAG2_READ_PENDING;
1738 } 1739 }
1739 if (context->cd & 1) { 1740 if (context->cd & 1) {
1740 return 0; 1741 warning("Read from VDP data port while writes are configured, CPU is now frozen. VDP Address: %X, CD: %X\n", context->address, context->cd);
1741 } 1742 }
1743 uint32_t old_frame = context->frame;
1742 while (!(context->flags & FLAG_READ_FETCHED)) { 1744 while (!(context->flags & FLAG_READ_FETCHED)) {
1743 vdp_run_context(context, context->cycles + ((context->regs[REG_MODE_4] & BIT_H40) ? 16 : 20)); 1745 vdp_run_context(context, context->cycles + ((context->regs[REG_MODE_4] & BIT_H40) ? 16 : 20));
1746 if (context->frame != old_frame) {
1747 if (!headless) {
1748 //TODO: make pushing frames to renderer automatic so this doesn't need to be here
1749 wait_render_frame(context, 0);
1750 }
1751 old_frame = context->frame;
1752 }
1744 } 1753 }
1745 context->flags &= ~FLAG_READ_FETCHED; 1754 context->flags &= ~FLAG_READ_FETCHED;
1746 //Should this happen after the prefetch or after the read? 1755 //Should this happen after the prefetch or after the read?
1747 context->address += context->regs[REG_AUTOINC]; 1756 context->address += context->regs[REG_AUTOINC];
1748 return context->prefetch; 1757 return context->prefetch;