    001package ibxm;
    002
    003import java.io.*;
    004
    005public class ProTracker {
    006    public static boolean is_mod( byte[] header_1084_bytes ) {
    007        boolean is_mod;
    008        is_mod = false;
    009        if( calculate_num_channels( header_1084_bytes ) > 0 ) {
    010            is_mod = true;
    011        }
    012        return is_mod;
    013    }
    014
    015    public static Module load_mod( byte[] header_1084_bytes, DataInput data_input ) throws IOException {
    016        int num_channels, channel_idx, panning;
    017        int sequence_length, restart_idx, sequence_idx;
    018        int num_patterns, pattern_idx, instrument_idx;
    019        Module module;
    020        num_channels = calculate_num_channels( header_1084_bytes );
    021        if( num_channels < 1 ) {
    022            throw new IllegalArgumentException( "ProTracker: Unrecognised module format!" );
    023        }
    024        module = new Module();
    025        module.song_title = ascii_text( header_1084_bytes, 0, 20 );
    026        module.pal = ( num_channels == 4 );
    027        module.global_volume = 64;
    028        module.channel_gain = IBXM.FP_ONE * 3 / 8;
    029        module.default_speed = 6;
    030        module.default_tempo = 125;
    031        module.set_num_channels( num_channels );
    032        for( channel_idx = 0; channel_idx < num_channels; channel_idx++ ) {
    033            panning = 64;
    034            if( ( channel_idx & 0x03 ) == 0x01 || ( channel_idx & 0x03 ) == 0x02 ) {
    035                panning = 192;
    036            }
    037            module.set_initial_panning( channel_idx, panning );
    038        }
    039        sequence_length = header_1084_bytes[ 950 ] & 0x7F;
    040        restart_idx = header_1084_bytes[ 951 ] & 0x7F;
    041        if( restart_idx >= sequence_length ) {
    042            restart_idx = 0;
    043        }
    044        module.restart_sequence_index = restart_idx;
    045        module.set_sequence_length( sequence_length );
    046        for( sequence_idx = 0; sequence_idx < sequence_length; sequence_idx++ ) {
    047            module.set_sequence( sequence_idx, header_1084_bytes[ 952 + sequence_idx ] & 0x7F );
    048        }
    049        num_patterns = calculate_num_patterns( header_1084_bytes );
    050        module.set_num_patterns( num_patterns );
    051        for( pattern_idx = 0; pattern_idx < num_patterns; pattern_idx++ ) {
    052            module.set_pattern( pattern_idx, read_mod_pattern( data_input, num_channels ) );
    053        }
    054        module.set_num_instruments( 31 );
    055        for( instrument_idx = 1; instrument_idx <= 31; instrument_idx++ ) {
    056            module.set_instrument( instrument_idx, read_mod_instrument( header_1084_bytes, instrument_idx, data_input ) );
    057        }
    058        return module;
    059    }
    060
    061    private static int calculate_num_patterns( byte[] module_header ) {
    062        int num_patterns, order_entry, pattern_idx;
    063        num_patterns = 0;
    064        for( pattern_idx = 0; pattern_idx < 128; pattern_idx++ ) {
    065            order_entry = module_header[ 952 + pattern_idx ] & 0x7F;
    066            if( order_entry >= num_patterns ) {
    067                num_patterns = order_entry + 1;
    068            }
    069        }
    070        return num_patterns;
    071    }
    072
    073    private static int calculate_num_channels( byte[] module_header ) {
    074        int num_channels;
    075        switch( ( module_header[ 1082 ] << 8 ) | module_header[ 1083 ] ) {
    076            case 0x4b2e: /* M.K. */
    077            case 0x4b21: /* M!K! */
    078            case 0x542e: /* N.T. */
    079            case 0x5434: /* FLT4 */
    080                num_channels = 4;
    081                break;
    082            case 0x484e: /* xCHN */
    083                num_channels = module_header[ 1080 ] - 48;
    084                break;
    085            case 0x4348: /* xxCH */
    086                num_channels = ( ( module_header[ 1080 ] - 48 ) * 10 ) + ( module_header[ 1081 ] - 48 );
    087                break;
    088            default:
    089                /* Not recognised. */
    090                num_channels = 0;
    091                break;
    092        }
    093        return num_channels;
    094    }
    095
    096    private static Pattern read_mod_pattern( DataInput data_input, int num_channels ) throws IOException {
    097        int input_idx, output_idx;
    098        int period, instrument, effect, effect_param;
    099        Pattern pattern;
    100        byte[] input_pattern_data, output_pattern_data;
    101        pattern = new Pattern();
    102        pattern.num_rows = 64;
    103        input_pattern_data = new byte[ 64 * num_channels * 4 ];
    104        output_pattern_data = new byte[ 64 * num_channels * 5 ];
    105        data_input.readFully( input_pattern_data );
    106        input_idx = 0;
    107        output_idx = 0;
    108        while( input_idx < input_pattern_data.length ) {
    109            period = ( input_pattern_data[ input_idx ] & 0x0F ) << 8;
    110            period = period | ( input_pattern_data[ input_idx + 1 ] & 0xFF );
    111            output_pattern_data[ output_idx ] = to_key( period );
    112            instrument = input_pattern_data[ input_idx ] & 0x10;
    113            instrument = instrument | ( ( input_pattern_data[ input_idx + 2 ] & 0xF0 ) >> 4 );
    114            output_pattern_data[ output_idx + 1 ] = ( byte ) instrument;
    115            effect = input_pattern_data[ input_idx + 2 ] & 0x0F;
    116            effect_param = input_pattern_data[ input_idx + 3 ] & 0xFF;
    117            if( effect == 0x01 && effect_param == 0 ) {
    118                /* Portamento up of zero has no effect. */
    119                effect = 0;
    120            }
    121            if( effect == 0x02 && effect_param == 0 ) {
    122                /* Portamento down of zero has no effect. */
    123                effect = 0;
    124            }
    125            if( effect == 0x08 && num_channels == 4 ) {
    126                /* Some Amiga mods use effect 0x08 for reasons other than panning.*/
    127                effect = 0;
    128                effect_param = 0;
    129            }
    130            if( effect == 0x0A && effect_param == 0 ) {
    131                /* Volume slide of zero has no effect.*/
    132                effect = 0;
    133            }
    134            if( effect == 0x05 && effect_param == 0 ) {
    135                /* Porta + Volume slide of zero has no effect.*/
    136                effect = 0x03;
    137            }
    138            if( effect == 0x06 && effect_param == 0 ) {
    139                /* Vibrato + Volume slide of zero has no effect.*/
    140                effect = 0x04;
    141            }
    142            output_pattern_data[ output_idx + 3 ] = ( byte ) effect;
    143            output_pattern_data[ output_idx + 4 ] = ( byte ) effect_param;
    144            input_idx += 4;
    145            output_idx += 5;
    146        }
    147        pattern.set_pattern_data( output_pattern_data );
    148        return pattern;
    149    }
    150
    151    private static Instrument read_mod_instrument( byte[] mod_header, int idx, DataInput data_input ) throws IOException  {
    152        int header_offset, sample_data_length;
    153        int loop_start, loop_length, sample_idx, fine_tune;
    154        Instrument instrument;
    155        Sample sample;
    156        byte[] raw_sample_data;
    157        short[] sample_data;
    158        header_offset = ( idx - 1 ) * 30 + 20;
    159        instrument = new Instrument();
    160        instrument.name = ascii_text( mod_header, header_offset, 22 );
    161        sample = new Sample();
    162        sample_data_length = unsigned_short_be( mod_header, header_offset + 22 ) << 1;
    163        fine_tune = mod_header[ header_offset + 24 ] & 0x0F;
    164        if( fine_tune > 7 ) {
    165            fine_tune -= 16;
    166        }
    167        sample.transpose = ( fine_tune << IBXM.FP_SHIFT ) / 96;
    168        sample.volume = mod_header[ header_offset + 25 ] & 0x7F;
    169        loop_start = unsigned_short_be( mod_header, header_offset + 26 ) << 1;
    170        loop_length = unsigned_short_be( mod_header, header_offset + 28 ) << 1;
    171        if( loop_length < 4 ) {
    172            loop_length = 0;
    173        }
    174        raw_sample_data = new byte[ sample_data_length ];
    175        sample_data = new short[ sample_data_length ];
    176        try {
    177            data_input.readFully( raw_sample_data );
    178        } catch( EOFException e ) {
    179            System.out.println( "ProTracker: Instrument " + idx + " has samples missing." );
    180        }
    181        for( sample_idx = 0; sample_idx < raw_sample_data.length; sample_idx++ ) {
    182            sample_data[ sample_idx ] = ( short ) ( raw_sample_data[ sample_idx ] << 8 );
    183        }
    184        sample.set_sample_data( sample_data, loop_start, loop_length, false );
    185        instrument.set_num_samples( 1 );
    186        instrument.set_sample( 0, sample );
    187        return instrument;
    188    }
    189
    190    private static byte to_key( int period ) {
    191        int oct, key;
    192        if( period < 32 ) {
    193            key = 0;
    194        } else {
    195            oct = LogTable.log_2( 7256 ) - LogTable.log_2( period );
    196            if( oct < 0 ) {
    197                key = 0;
    198            } else {
    199                key = oct * 12;
    200                key = key >> ( IBXM.FP_SHIFT - 1 );
    201                key = ( key >> 1 ) + ( key & 1 );
    202            }
    203        }
    204        return ( byte ) key;
    205    }
    206
    207    private static int unsigned_short_be( byte[] buf, int offset ) {
    208        int value;
    209        value = ( buf[ offset ] & 0xFF ) << 8;
    210        value = value | ( buf[ offset + 1 ] & 0xFF );
    211        return value;
    212    }
    213
    214    private static String ascii_text( byte[] buffer, int offset, int length ) {
    215        int idx, chr;
    216        byte[] string_buffer;
    217        String string;
    218        string_buffer = new byte[ length ];
    219        for( idx = 0; idx < length; idx++ ) {
    220            chr = buffer[ offset + idx ];
    221            if( chr < 32 ) {
    222                chr = 32;
    223            }
    224            string_buffer[ idx ] = ( byte ) chr;
    225        }
    226        try {
    227            string = new String( string_buffer, 0, length, "ISO-8859-1" );
    228        } catch( UnsupportedEncodingException e ) {
    229            string = "";
    230        }
    231        return string;
    232    }
    233}
    234