kopia lustrzana https://github.com/Jean-MarcHarvengt/MCUME
193 wiersze
5.0 KiB
C
Executable File
193 wiersze
5.0 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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** map050.c
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**
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** Mapper #50 (SMB2j - 3rd discovered variation)
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** Implementation by Firebug
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** Mapper information courtesy of Kevin Horton
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** $Id: map050.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 #50 IRQ reset routine */
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/********************************/
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static void map50_irq_reset (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 #50: 3rd discovered variation of SMB2j cart bootleg */
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/**************************************************************/
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static void map50_init (void)
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{
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/* Set the hardwired pages */
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mmc_bankrom (8, 0x6000, 0x0F);
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mmc_bankrom (8, 0x8000, 0x08);
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mmc_bankrom (8, 0xA000, 0x09);
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mmc_bankrom (8, 0xE000, 0x0B);
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/* Reset the IRQ counter */
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map50_irq_reset ();
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/* Done */
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return;
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}
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/****************************************/
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/* Mapper #50 callback for IRQ handling */
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/****************************************/
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static void map50_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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/* IRQ line is hooked to Q12 of the counter */
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if (irq.counter & 0x1000)
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{
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/* Trigger the IRQ */
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nes_irq ();
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/* Reset the counter */
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map50_irq_reset ();
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}
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}
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}
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/******************************************/
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/* Mapper #50 write handler ($4000-$5FFF) */
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/******************************************/
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static void map50_write (uint32 address, uint8 value)
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{
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uint8 selectable_bank;
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/* For address to be decoded, A5 must be high and A6 low */
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if ((address & 0x60) != 0x20) return;
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/* A8 low = $C000-$DFFF page selection */
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/* A8 high = IRQ timer toggle */
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if (address & 0x100)
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{
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/* IRQ settings */
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if (value & 0x01) irq.enabled = true;
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else map50_irq_reset ();
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}
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else
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{
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/* Stupid data line swapping */
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selectable_bank = 0x00;
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if (value & 0x08) selectable_bank |= 0x08;
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if (value & 0x04) selectable_bank |= 0x02;
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if (value & 0x02) selectable_bank |= 0x01;
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if (value & 0x01) selectable_bank |= 0x04;
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mmc_bankrom (8, 0xC000, selectable_bank);
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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 map50_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 map50_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 map50_memwrite [] =
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{
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{ 0x4000, 0x5FFF, map50_write },
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{ -1, -1, NULL }
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};
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const mapintf_t map50_intf =
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{
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50, /* Mapper number */
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"SMB2j (3rd discovered variant)", /* Mapper name */
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map50_init, /* Initialization routine */
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NULL, /* VBlank callback */
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map50_hblank, /* HBlank callback */
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map50_getstate, /* Get state (SNSS) */
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map50_setstate, /* Set state (SNSS) */
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NULL, /* Memory read structure */
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map50_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: map050.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 2000/12/27 19:22:13 firebug
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** initial revision
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**
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**
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*/
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