kopia lustrzana https://github.com/Jean-MarcHarvengt/MCUME
174 wiersze
4.6 KiB
C
Executable File
174 wiersze
4.6 KiB
C
Executable File
/*
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** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
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**
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**
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** This program is free software; you can redistribute it and/or
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** modify it under the terms of version 2 of the GNU Library General
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** Public License as published by the Free Software Foundation.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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** Library General Public License for more details. To obtain a
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** copy of the GNU Library General Public License, write to the Free
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** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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**
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** Any permitted reproduction of these routines, in whole or in part,
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** must bear this legend.
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**
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**
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** map073.c
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**
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** Mapper #73 (Konami VRC3)
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** Implementation by Firebug
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** $Id: map073.c,v 1.2 2001/04/27 14:37:11 neil Exp $
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**
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*/
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#include "noftypes.h"
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#include "nes_mmc.h"
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#include "nes.h"
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#include "libsnss.h"
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#include "log.h"
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static struct
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{
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bool enabled;
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uint32 counter;
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} irq;
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/**************************/
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/* Mapper #73: Salamander */
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/**************************/
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static void map73_init (void)
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{
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/* Turn off IRQs */
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irq.enabled = false;
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irq.counter = 0x0000;
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/* Done */
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return;
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}
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/****************************************/
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/* Mapper #73 callback for IRQ handling */
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/****************************************/
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static void map73_hblank (int vblank)
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{
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/* Counter is M2 based so it doesn't matter whether */
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/* the PPU is in its VBlank period or not */
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UNUSED (vblank);
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/* Increment the counter if it is enabled and check for strike */
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if (irq.enabled)
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{
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/* Is there a constant for cycles per scanline? */
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/* If so, someone ought to substitute it here */
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irq.counter = irq.counter + 114;
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/* Counter triggered on overflow into Q16 */
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if (irq.counter & 0x10000)
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{
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/* Clip to sixteen-bit word */
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irq.counter &= 0xFFFF;
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/* Trigger the IRQ */
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nes_irq ();
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/* Shut off IRQ counter */
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irq.enabled = false;
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}
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}
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}
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/******************************************/
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/* Mapper #73 write handler ($8000-$FFFF) */
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/******************************************/
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static void map73_write (uint32 address, uint8 value)
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{
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switch (address & 0xF000)
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{
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case 0x8000: irq.counter &= 0xFFF0;
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irq.counter |= (uint32) (value);
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break;
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case 0x9000: irq.counter &= 0xFF0F;
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irq.counter |= (uint32) (value << 4);
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break;
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case 0xA000: irq.counter &= 0xF0FF;
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irq.counter |= (uint32) (value << 8);
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break;
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case 0xB000: irq.counter &= 0x0FFF;
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irq.counter |= (uint32) (value << 12);
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break;
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case 0xC000: if (value & 0x02) irq.enabled = true;
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else irq.enabled = false;
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break;
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case 0xF000: mmc_bankrom (16, 0x8000, value);
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default: break;
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}
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/* Done */
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return;
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}
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/****************************************************/
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/* Shove extra mapper information into a SNSS block */
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/****************************************************/
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static void map73_setstate (SnssMapperBlock *state)
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{
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/* TODO: Store SNSS information */
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UNUSED (state);
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/* Done */
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return;
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}
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/*****************************************************/
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/* Pull extra mapper information out of a SNSS block */
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/*****************************************************/
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static void map73_getstate (SnssMapperBlock *state)
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{
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/* TODO: Retrieve SNSS information */
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UNUSED (state);
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/* Done */
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return;
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}
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static const map_memwrite map73_memwrite [] =
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{
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{ 0x8000, 0xFFFF, map73_write },
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{ -1, -1, NULL }
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};
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const mapintf_t map73_intf =
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{
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73, /* Mapper number */
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"Konami VRC3", /* Mapper name */
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map73_init, /* Initialization routine */
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NULL, /* VBlank callback */
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map73_hblank, /* HBlank callback */
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map73_getstate, /* Get state (SNSS) */
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map73_setstate, /* Set state (SNSS) */
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NULL, /* Memory read structure */
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map73_memwrite, /* Memory write structure */
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NULL /* External sound device */
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};
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/*
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** $Log: map073.c,v $
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** Revision 1.2 2001/04/27 14:37:11 neil
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** wheeee
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**
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** Revision 1.1 2001/04/27 12:54:40 neil
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** blah
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**
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** Revision 1.1 2001/04/27 10:57:41 neil
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** wheee
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**
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** Revision 1.1 2000/12/30 06:35:05 firebug
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** Initial revision
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**
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**
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*/
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