121 lines
2.8 KiB
C++
121 lines
2.8 KiB
C++
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// Nes_Emu 0.7.0. http://www.slack.net/~ant/
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#include "Nes_Cart.h"
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#include <stdlib.h>
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#include <string.h>
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/* Copyright (C) 2004-2006 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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more details. You should have received a copy of the GNU Lesser General
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Public License along with this module; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include "blargg_source.h"
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char const Nes_Cart::not_ines_file [] = "Not an iNES file";
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Nes_Cart::Nes_Cart()
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{
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prg_ = NULL;
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chr_ = NULL;
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clear();
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}
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Nes_Cart::~Nes_Cart()
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{
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clear();
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}
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void Nes_Cart::clear()
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{
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if ( prg_ )
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free( prg_ );
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prg_ = NULL;
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if ( chr_ )
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free( chr_ );
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chr_ = NULL;
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prg_size_ = 0;
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chr_size_ = 0;
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mapper = 0;
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}
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long Nes_Cart::round_to_bank_size( long n )
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{
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n += bank_size - 1;
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return n - n % bank_size;
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}
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const char * Nes_Cart::resize_prg( long size )
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{
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if ( size != prg_size_ )
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{
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// padding allows CPU to always read operands of instruction, which
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// might go past end of data
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void* p = realloc( prg_, round_to_bank_size( size ) + 2 );
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CHECK_ALLOC( p || !size );
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prg_ = (uint8_t*) p;
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prg_size_ = size;
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}
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return 0;
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}
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const char * Nes_Cart::resize_chr( long size )
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{
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if ( size != chr_size_ )
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{
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void* p = realloc( chr_, round_to_bank_size( size ) );
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CHECK_ALLOC( p || !size );
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chr_ = (uint8_t*) p;
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chr_size_ = size;
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}
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return 0;
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}
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// iNES reading
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struct ines_header_t {
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uint8_t signature [4];
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uint8_t prg_count; // number of 16K PRG banks
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uint8_t chr_count; // number of 8K CHR banks
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uint8_t flags; // MMMM FTBV Mapper low, Four-screen, Trainer, Battery, V mirror
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uint8_t flags2; // MMMM --XX Mapper high 4 bits
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uint8_t zero [8]; // if zero [7] is non-zero, treat flags2 as zero
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};
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BOOST_STATIC_ASSERT( sizeof (ines_header_t) == 16 );
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const char * Nes_Cart::load_ines( Auto_File_Reader in )
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{
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RETURN_ERR( in.open() );
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ines_header_t h;
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RETURN_ERR( in->read( &h, sizeof h ) );
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if ( 0 != memcmp( h.signature, "NES\x1A", 4 ) )
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return not_ines_file;
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if ( h.zero [7] ) // handle header defaced by a fucking idiot's handle
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h.flags2 = 0;
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set_mapper( h.flags, h.flags2 );
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if ( h.flags & 0x04 ) // skip trainer
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RETURN_ERR( in->skip( 512 ) );
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RETURN_ERR( resize_prg( h.prg_count * 16 * 1024L ) );
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RETURN_ERR( resize_chr( h.chr_count * 8 * 1024L ) );
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RETURN_ERR( in->read( prg(), prg_size() ) );
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RETURN_ERR( in->read( chr(), chr_size() ) );
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return 0;
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}
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