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405 lines
9.8 KiB
C++
405 lines
9.8 KiB
C++
// Game_Music_Emu 0.6.0. http://www.slack.net/~ant/
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#include "Ay_Emu.h"
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#include "blargg_endian.h"
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#include <string.h>
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/* Copyright (C) 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 more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "blargg_source.h"
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long const spectrum_clock = 3546900;
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long const cpc_clock = 2000000;
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unsigned const ram_start = 0x4000;
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int const osc_count = Ay_Apu::osc_count + 1;
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Ay_Emu::Ay_Emu()
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{
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beeper_output = 0;
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set_type( gme_ay_type );
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static const char* const names [osc_count] = {
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"Wave 1", "Wave 2", "Wave 3", "Beeper"
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};
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set_voice_names( names );
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static int const types [osc_count] = {
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wave_type | 0, wave_type | 1, wave_type | 2, mixed_type | 0
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};
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set_voice_types( types );
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set_silence_lookahead( 6 );
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}
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Ay_Emu::~Ay_Emu() { }
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// Track info
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static byte const* get_data( Ay_Emu::file_t const& file, byte const* ptr, int min_size )
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{
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long pos = ptr - (byte const*) file.header;
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long file_size = file.end - (byte const*) file.header;
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assert( (unsigned long) pos <= (unsigned long) file_size - 2 );
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int offset = (BOOST::int16_t) get_be16( ptr );
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if ( !offset || blargg_ulong (pos + offset) > blargg_ulong (file_size - min_size) )
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return 0;
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return ptr + offset;
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}
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static blargg_err_t parse_header( byte const* in, long size, Ay_Emu::file_t* out )
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{
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typedef Ay_Emu::header_t header_t;
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out->header = (header_t const*) in;
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out->end = in + size;
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if ( size < Ay_Emu::header_size )
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return gme_wrong_file_type;
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header_t const& h = *(header_t const*) in;
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if ( memcmp( h.tag, "ZXAYEMUL", 8 ) )
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return gme_wrong_file_type;
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out->tracks = get_data( *out, h.track_info, (h.max_track + 1) * 4 );
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if ( !out->tracks )
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return "Missing track data";
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return 0;
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}
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static void copy_ay_fields( Ay_Emu::file_t const& file, track_info_t* out, int track )
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{
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Gme_File::copy_field_( out->song, (char const*) get_data( file, file.tracks + track * 4, 1 ) );
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byte const* track_info = get_data( file, file.tracks + track * 4 + 2, 6 );
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if ( track_info )
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out->length = get_be16( track_info + 4 ) * (1000L / 50); // frames to msec
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Gme_File::copy_field_( out->author, (char const*) get_data( file, file.header->author, 1 ) );
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Gme_File::copy_field_( out->comment, (char const*) get_data( file, file.header->comment, 1 ) );
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}
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blargg_err_t Ay_Emu::track_info_( track_info_t* out, int track ) const
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{
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copy_ay_fields( file, out, track );
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return 0;
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}
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struct Ay_File : Gme_Info_
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{
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Ay_Emu::file_t file;
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Ay_File() { set_type( gme_ay_type ); }
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blargg_err_t load_mem_( byte const* begin, long size )
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{
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RETURN_ERR( parse_header( begin, size, &file ) );
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set_track_count( file.header->max_track + 1 );
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return 0;
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}
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blargg_err_t track_info_( track_info_t* out, int track ) const
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{
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copy_ay_fields( file, out, track );
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return 0;
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}
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};
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static Music_Emu* new_ay_emu () { return BLARGG_NEW Ay_Emu ; }
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static Music_Emu* new_ay_file() { return BLARGG_NEW Ay_File; }
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static gme_type_t_ const gme_ay_type_ = { "ZX Spectrum", 0, &new_ay_emu, &new_ay_file, "AY", 1 };
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gme_type_t const gme_ay_type = &gme_ay_type_;
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// Setup
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blargg_err_t Ay_Emu::load_mem_( byte const* in, long size )
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{
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assert( offsetof (header_t,track_info [2]) == header_size );
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RETURN_ERR( parse_header( in, size, &file ) );
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set_track_count( file.header->max_track + 1 );
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if ( file.header->vers > 2 )
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set_warning( "Unknown file version" );
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set_voice_count( osc_count );
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apu.volume( gain() );
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return setup_buffer( spectrum_clock );
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}
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void Ay_Emu::update_eq( blip_eq_t const& eq )
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{
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apu.treble_eq( eq );
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}
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void Ay_Emu::set_voice( int i, Blip_Buffer* center, Blip_Buffer*, Blip_Buffer* )
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{
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if ( i >= Ay_Apu::osc_count )
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beeper_output = center;
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else
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apu.osc_output( i, center );
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}
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// Emulation
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void Ay_Emu::set_tempo_( double t )
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{
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play_period = blip_time_t (clock_rate() / 50 / t);
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}
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blargg_err_t Ay_Emu::start_track_( int track )
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{
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RETURN_ERR( Classic_Emu::start_track_( track ) );
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memset( mem.ram + 0x0000, 0xC9, 0x100 ); // fill RST vectors with RET
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memset( mem.ram + 0x0100, 0xFF, 0x4000 - 0x100 );
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memset( mem.ram + ram_start, 0x00, sizeof mem.ram - ram_start );
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memset( mem.padding1, 0xFF, sizeof mem.padding1 );
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memset( mem.ram + 0x10000, 0xFF, sizeof mem.ram - 0x10000 );
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// locate data blocks
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byte const* const data = get_data( file, file.tracks + track * 4 + 2, 14 );
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if ( !data ) return "File data missing";
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byte const* const more_data = get_data( file, data + 10, 6 );
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if ( !more_data ) return "File data missing";
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byte const* blocks = get_data( file, data + 12, 8 );
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if ( !blocks ) return "File data missing";
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// initial addresses
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cpu::reset( mem.ram );
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r.sp = get_be16( more_data );
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r.b.a = r.b.b = r.b.d = r.b.h = data [8];
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r.b.flags = r.b.c = r.b.e = r.b.l = data [9];
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r.alt.w = r.w;
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r.ix = r.iy = r.w.hl;
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unsigned addr = get_be16( blocks );
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if ( !addr ) return "File data missing";
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unsigned init = get_be16( more_data + 2 );
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if ( !init )
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init = addr;
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// copy blocks into memory
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do
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{
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blocks += 2;
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unsigned len = get_be16( blocks ); blocks += 2;
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if ( addr + len > 0x10000 )
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{
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set_warning( "Bad data block size" );
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len = 0x10000 - addr;
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}
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check( len );
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byte const* in = get_data( file, blocks, 0 ); blocks += 2;
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if ( len > blargg_ulong (file.end - in) )
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{
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set_warning( "Missing file data" );
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len = file.end - in;
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}
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//debug_printf( "addr: $%04X, len: $%04X\n", addr, len );
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if ( addr < ram_start && addr >= 0x400 ) // several tracks use low data
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debug_printf( "Block addr in ROM\n" );
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memcpy( mem.ram + addr, in, len );
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if ( file.end - blocks < 8 )
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{
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set_warning( "Missing file data" );
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break;
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}
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}
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while ( (addr = get_be16( blocks )) != 0 );
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// copy and configure driver
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static byte const passive [] = {
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0xF3, // DI
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0xCD, 0, 0, // CALL init
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0xED, 0x5E, // LOOP: IM 2
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0xFB, // EI
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0x76, // HALT
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0x18, 0xFA // JR LOOP
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};
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static byte const active [] = {
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0xF3, // DI
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0xCD, 0, 0, // CALL init
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0xED, 0x56, // LOOP: IM 1
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0xFB, // EI
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0x76, // HALT
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0xCD, 0, 0, // CALL play
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0x18, 0xF7 // JR LOOP
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};
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memcpy( mem.ram, passive, sizeof passive );
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unsigned play_addr = get_be16( more_data + 4 );
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//debug_printf( "Play: $%04X\n", play_addr );
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if ( play_addr )
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{
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memcpy( mem.ram, active, sizeof active );
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mem.ram [ 9] = play_addr;
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mem.ram [10] = play_addr >> 8;
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}
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mem.ram [2] = init;
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mem.ram [3] = init >> 8;
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mem.ram [0x38] = 0xFB; // Put EI at interrupt vector (followed by RET)
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memcpy( mem.ram + 0x10000, mem.ram, 0x80 ); // some code wraps around (ugh)
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beeper_delta = int (apu.amp_range * 0.65);
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last_beeper = 0;
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apu.reset();
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next_play = play_period;
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// start at spectrum speed
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change_clock_rate( spectrum_clock );
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set_tempo( tempo() );
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spectrum_mode = false;
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cpc_mode = false;
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cpc_latch = 0;
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return 0;
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}
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// Emulation
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void Ay_Emu::cpu_out_misc( cpu_time_t time, unsigned addr, int data )
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{
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if ( !cpc_mode )
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{
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switch ( addr & 0xFEFF )
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{
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case 0xFEFD:
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spectrum_mode = true;
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apu_addr = data & 0x0F;
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return;
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case 0xBEFD:
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spectrum_mode = true;
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apu.write( time, apu_addr, data );
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return;
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}
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}
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if ( !spectrum_mode )
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{
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switch ( addr >> 8 )
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{
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case 0xF6:
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switch ( data & 0xC0 )
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{
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case 0xC0:
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apu_addr = cpc_latch & 0x0F;
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goto enable_cpc;
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case 0x80:
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apu.write( time, apu_addr, cpc_latch );
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goto enable_cpc;
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}
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break;
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case 0xF4:
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cpc_latch = data;
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goto enable_cpc;
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}
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}
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debug_printf( "Unmapped OUT: $%04X <- $%02X\n", addr, data );
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return;
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enable_cpc:
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if ( !cpc_mode )
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{
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cpc_mode = true;
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change_clock_rate( cpc_clock );
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set_tempo( tempo() );
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}
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}
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void ay_cpu_out( Ay_Cpu* cpu, cpu_time_t time, unsigned addr, int data )
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{
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Ay_Emu& emu = STATIC_CAST(Ay_Emu&,*cpu);
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if ( (addr & 0xFF) == 0xFE && !emu.cpc_mode )
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{
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int delta = emu.beeper_delta;
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data &= 0x10;
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if ( emu.last_beeper != data )
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{
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emu.last_beeper = data;
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emu.beeper_delta = -delta;
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emu.spectrum_mode = true;
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if ( emu.beeper_output )
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emu.apu.synth_.offset( time, delta, emu.beeper_output );
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}
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}
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else
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{
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emu.cpu_out_misc( time, addr, data );
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}
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}
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int ay_cpu_in( Ay_Cpu*, unsigned addr )
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{
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// keyboard read and other things
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if ( (addr & 0xFF) == 0xFE )
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return 0xFF; // other values break some beeper tunes
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debug_printf( "Unmapped IN : $%04X\n", addr );
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return 0xFF;
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}
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blargg_err_t Ay_Emu::run_clocks( blip_time_t& duration, int )
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{
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set_time( 0 );
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if ( !(spectrum_mode | cpc_mode) )
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duration /= 2; // until mode is set, leave room for halved clock rate
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while ( time() < duration )
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{
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cpu::run( min( duration, (blip_time_t) next_play ) );
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if ( time() >= next_play )
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{
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next_play += play_period;
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if ( r.iff1 )
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{
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if ( mem.ram [r.pc] == 0x76 )
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r.pc++;
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r.iff1 = r.iff2 = 0;
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mem.ram [--r.sp] = uint8_t (r.pc >> 8);
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mem.ram [--r.sp] = uint8_t (r.pc);
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r.pc = 0x38;
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cpu::adjust_time( 12 );
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if ( r.im == 2 )
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{
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cpu::adjust_time( 6 );
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unsigned addr = r.i * 0x100u + 0xFF;
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r.pc = mem.ram [(addr + 1) & 0xFFFF] * 0x100u + mem.ram [addr];
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}
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}
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}
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}
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duration = time();
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next_play -= duration;
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check( next_play >= 0 );
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adjust_time( -duration );
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apu.end_frame( duration );
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return 0;
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}
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