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Ay_Emu.cpp
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Ay_Emu.cpp
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// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
#include "Ay_Emu.h"
#include "blargg_endian.h"
#include <string.h>
/* Copyright (C) 2006 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details. You should have received a copy of the GNU Lesser General Public
License along with this module; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
#include "blargg_source.h"
long const spectrum_clock = 3546900;
long const cpc_clock = 2000000;
unsigned const ram_start = 0x4000;
int const osc_count = Ay_Apu::osc_count + 1;
Ay_Emu::Ay_Emu()
{
beeper_output = 0;
set_type( gme_ay_type );
static const char* const names [osc_count] = {
"Wave 1", "Wave 2", "Wave 3", "Beeper"
};
set_voice_names( names );
static int const types [osc_count] = {
wave_type | 0, wave_type | 1, wave_type | 2, mixed_type | 0
};
set_voice_types( types );
set_silence_lookahead( 6 );
}
Ay_Emu::~Ay_Emu() { }
// Track info
static byte const* get_data( Ay_Emu::file_t const& file, byte const* ptr, int min_size )
{
long pos = ptr - (byte const*) file.header;
long file_size = file.end - (byte const*) file.header;
assert( (unsigned long) pos <= (unsigned long) file_size - 2 );
int offset = (BOOST::int16_t) get_be16( ptr );
if ( !offset || blargg_ulong (pos + offset) > blargg_ulong (file_size - min_size) )
return 0;
return ptr + offset;
}
static blargg_err_t parse_header( byte const* in, long size, Ay_Emu::file_t* out )
{
typedef Ay_Emu::header_t header_t;
out->header = (header_t const*) in;
out->end = in + size;
if ( size < Ay_Emu::header_size )
return gme_wrong_file_type;
header_t const& h = *(header_t const*) in;
if ( memcmp( h.tag, "ZXAYEMUL", 8 ) )
return gme_wrong_file_type;
out->tracks = get_data( *out, h.track_info, (h.max_track + 1) * 4 );
if ( !out->tracks )
return "Missing track data";
return 0;
}
static void copy_ay_fields( Ay_Emu::file_t const& file, track_info_t* out, int track )
{
Gme_File::copy_field_( out->song, (char const*) get_data( file, file.tracks + track * 4, 1 ) );
byte const* track_info = get_data( file, file.tracks + track * 4 + 2, 6 );
if ( track_info )
out->length = get_be16( track_info + 4 ) * (1000L / 50); // frames to msec
Gme_File::copy_field_( out->author, (char const*) get_data( file, file.header->author, 1 ) );
Gme_File::copy_field_( out->comment, (char const*) get_data( file, file.header->comment, 1 ) );
}
blargg_err_t Ay_Emu::track_info_( track_info_t* out, int track ) const
{
copy_ay_fields( file, out, track );
return 0;
}
struct Ay_File : Gme_Info_
{
Ay_Emu::file_t file;
Ay_File() { set_type( gme_ay_type ); }
blargg_err_t load_mem_( byte const* begin, long size )
{
RETURN_ERR( parse_header( begin, size, &file ) );
set_track_count( file.header->max_track + 1 );
return 0;
}
blargg_err_t track_info_( track_info_t* out, int track ) const
{
copy_ay_fields( file, out, track );
return 0;
}
};
static Music_Emu* new_ay_emu () { return BLARGG_NEW Ay_Emu ; }
static Music_Emu* new_ay_file() { return BLARGG_NEW Ay_File; }
static gme_type_t_ const gme_ay_type_ = { "ZX Spectrum", 0, &new_ay_emu, &new_ay_file, "AY", 1 };
gme_type_t const gme_ay_type = &gme_ay_type_;
// Setup
blargg_err_t Ay_Emu::load_mem_( byte const* in, long size )
{
assert( offsetof (header_t,track_info [2]) == header_size );
RETURN_ERR( parse_header( in, size, &file ) );
set_track_count( file.header->max_track + 1 );
if ( file.header->vers > 2 )
set_warning( "Unknown file version" );
set_voice_count( osc_count );
apu.volume( gain() );
return setup_buffer( spectrum_clock );
}
void Ay_Emu::update_eq( blip_eq_t const& eq )
{
apu.treble_eq( eq );
}
void Ay_Emu::set_voice( int i, Blip_Buffer* center, Blip_Buffer*, Blip_Buffer* )
{
if ( i >= Ay_Apu::osc_count )
beeper_output = center;
else
apu.osc_output( i, center );
}
// Emulation
void Ay_Emu::set_tempo_( double t )
{
play_period = blip_time_t (clock_rate() / 50 / t);
}
blargg_err_t Ay_Emu::start_track_( int track )
{
RETURN_ERR( Classic_Emu::start_track_( track ) );
memset( mem.ram + 0x0000, 0xC9, 0x100 ); // fill RST vectors with RET
memset( mem.ram + 0x0100, 0xFF, 0x4000 - 0x100 );
memset( mem.ram + ram_start, 0x00, sizeof mem.ram - ram_start );
memset( mem.padding1, 0xFF, sizeof mem.padding1 );
memset( mem.ram + 0x10000, 0xFF, sizeof mem.ram - 0x10000 );
// locate data blocks
byte const* const data = get_data( file, file.tracks + track * 4 + 2, 14 );
if ( !data ) return "File data missing";
byte const* const more_data = get_data( file, data + 10, 6 );
if ( !more_data ) return "File data missing";
byte const* blocks = get_data( file, data + 12, 8 );
if ( !blocks ) return "File data missing";
// initial addresses
cpu::reset( mem.ram );
r.sp = get_be16( more_data );
r.b.a = r.b.b = r.b.d = r.b.h = data [8];
r.b.flags = r.b.c = r.b.e = r.b.l = data [9];
r.alt.w = r.w;
r.ix = r.iy = r.w.hl;
unsigned addr = get_be16( blocks );
if ( !addr ) return "File data missing";
unsigned init = get_be16( more_data + 2 );
if ( !init )
init = addr;
// copy blocks into memory
do
{
blocks += 2;
unsigned len = get_be16( blocks ); blocks += 2;
if ( addr + len > 0x10000 )
{
set_warning( "Bad data block size" );
len = 0x10000 - addr;
}
check( len );
byte const* in = get_data( file, blocks, 0 ); blocks += 2;
if ( len > blargg_ulong (file.end - in) )
{
set_warning( "Missing file data" );
len = file.end - in;
}
//debug_printf( "addr: $%04X, len: $%04X\n", addr, len );
if ( addr < ram_start && addr >= 0x400 ) // several tracks use low data
debug_printf( "Block addr in ROM\n" );
memcpy( mem.ram + addr, in, len );
if ( file.end - blocks < 8 )
{
set_warning( "Missing file data" );
break;
}
}
while ( (addr = get_be16( blocks )) != 0 );
// copy and configure driver
static byte const passive [] = {
0xF3, // DI
0xCD, 0, 0, // CALL init
0xED, 0x5E, // LOOP: IM 2
0xFB, // EI
0x76, // HALT
0x18, 0xFA // JR LOOP
};
static byte const active [] = {
0xF3, // DI
0xCD, 0, 0, // CALL init
0xED, 0x56, // LOOP: IM 1
0xFB, // EI
0x76, // HALT
0xCD, 0, 0, // CALL play
0x18, 0xF7 // JR LOOP
};
memcpy( mem.ram, passive, sizeof passive );
unsigned play_addr = get_be16( more_data + 4 );
//debug_printf( "Play: $%04X\n", play_addr );
if ( play_addr )
{
memcpy( mem.ram, active, sizeof active );
mem.ram [ 9] = play_addr;
mem.ram [10] = play_addr >> 8;
}
mem.ram [2] = init;
mem.ram [3] = init >> 8;
mem.ram [0x38] = 0xFB; // Put EI at interrupt vector (followed by RET)
memcpy( mem.ram + 0x10000, mem.ram, 0x80 ); // some code wraps around (ugh)
beeper_delta = int (apu.amp_range * 0.65);
last_beeper = 0;
apu.reset();
next_play = play_period;
// start at spectrum speed
change_clock_rate( spectrum_clock );
set_tempo( tempo() );
spectrum_mode = false;
cpc_mode = false;
cpc_latch = 0;
return 0;
}
// Emulation
void Ay_Emu::cpu_out_misc( cpu_time_t time, unsigned addr, int data )
{
if ( !cpc_mode )
{
switch ( addr & 0xFEFF )
{
case 0xFEFD:
spectrum_mode = true;
apu_addr = data & 0x0F;
return;
case 0xBEFD:
spectrum_mode = true;
apu.write( time, apu_addr, data );
return;
}
}
if ( !spectrum_mode )
{
switch ( addr >> 8 )
{
case 0xF6:
switch ( data & 0xC0 )
{
case 0xC0:
apu_addr = cpc_latch & 0x0F;
goto enable_cpc;
case 0x80:
apu.write( time, apu_addr, cpc_latch );
goto enable_cpc;
}
break;
case 0xF4:
cpc_latch = data;
goto enable_cpc;
}
}
debug_printf( "Unmapped OUT: $%04X <- $%02X\n", addr, data );
return;
enable_cpc:
if ( !cpc_mode )
{
cpc_mode = true;
change_clock_rate( cpc_clock );
set_tempo( tempo() );
}
}
void ay_cpu_out( Ay_Cpu* cpu, cpu_time_t time, unsigned addr, int data )
{
Ay_Emu& emu = STATIC_CAST(Ay_Emu&,*cpu);
if ( (addr & 0xFF) == 0xFE && !emu.cpc_mode )
{
int delta = emu.beeper_delta;
data &= 0x10;
if ( emu.last_beeper != data )
{
emu.last_beeper = data;
emu.beeper_delta = -delta;
emu.spectrum_mode = true;
if ( emu.beeper_output )
emu.apu.synth_.offset( time, delta, emu.beeper_output );
}
}
else
{
emu.cpu_out_misc( time, addr, data );
}
}
int ay_cpu_in( Ay_Cpu*, unsigned addr )
{
// keyboard read and other things
if ( (addr & 0xFF) == 0xFE )
return 0xFF; // other values break some beeper tunes
debug_printf( "Unmapped IN : $%04X\n", addr );
return 0xFF;
}
blargg_err_t Ay_Emu::run_clocks( blip_time_t& duration, int )
{
set_time( 0 );
if ( !(spectrum_mode | cpc_mode) )
duration /= 2; // until mode is set, leave room for halved clock rate
while ( time() < duration )
{
cpu::run( min( duration, (blip_time_t) next_play ) );
if ( time() >= next_play )
{
next_play += play_period;
if ( r.iff1 )
{
if ( mem.ram [r.pc] == 0x76 )
r.pc++;
r.iff1 = r.iff2 = 0;
mem.ram [--r.sp] = uint8_t (r.pc >> 8);
mem.ram [--r.sp] = uint8_t (r.pc);
r.pc = 0x38;
cpu::adjust_time( 12 );
if ( r.im == 2 )
{
cpu::adjust_time( 6 );
unsigned addr = r.i * 0x100u + 0xFF;
r.pc = mem.ram [(addr + 1) & 0xFFFF] * 0x100u + mem.ram [addr];
}
}
}
}
duration = time();
next_play -= duration;
check( next_play >= 0 );
adjust_time( -duration );
apu.end_frame( duration );
return 0;
}

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