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