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https://github.com/holub/mame
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149 lines
3.6 KiB
C
149 lines
3.6 KiB
C
/********************************************************************
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Support for EACA Colour Genie .cas cassette images
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Current state: Not working. Only the sync signal and 0x66 byte get
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recognized.
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********************************************************************/
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#include "formats/cgen_cas.h"
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#define TAPE_HEADER "Colour Genie - Virtual Tape File"
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#define SMPLO -32768
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#define SMPHI 32767
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static int cas_size;
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static int level;
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static int cgenie_output_byte(INT16 *buffer, int sample_count, UINT8 data)
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{
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int i;
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int samples = 0;
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for ( i = 0; i < 8; i++ )
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{
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/* Output bit boundary */
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level ^= 1;
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if ( buffer )
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buffer[ sample_count + samples ] = level ? SMPHI : SMPLO;
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samples++;
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/* Output bit */
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if ( data & 0x80 )
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level ^= 1;
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if ( buffer )
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buffer[ sample_count + samples ] = level ? SMPHI : SMPLO;
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samples++;
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data <<= 1;
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}
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return samples;
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}
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static int cgenie_handle_cas(INT16 *buffer, const UINT8 *casdata)
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{
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int i, data_pos, sample_count;
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data_pos = 0;
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sample_count = 0;
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level = 0;
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/* Check for presence of optional header */
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if ( ! memcmp( casdata, TAPE_HEADER, sizeof(TAPE_HEADER) - 1 ) )
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{
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/* Search for 0x00 or end of file */
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while ( data_pos < cas_size && casdata[data_pos] )
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data_pos++;
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/* If we're at the end of the file it's not a valid .cas file */
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if ( data_pos == cas_size )
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return -1;
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/* Skip the 0x00 byte */
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data_pos++;
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}
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/* If we're at the end of the file it's not a valid .cas file */
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if ( data_pos == cas_size )
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return -1;
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/* Check for beginning of tape file marker */
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if ( casdata[data_pos] != 0x66 )
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return -1;
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/* Create header */
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for ( i = 0; i < 256; i++ )
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sample_count += cgenie_output_byte( buffer, sample_count, 0xaa );
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/* Start outputting data */
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while( data_pos < cas_size )
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{
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sample_count += cgenie_output_byte( buffer, sample_count, casdata[data_pos] );
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data_pos++;
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}
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sample_count += cgenie_output_byte( buffer, sample_count, 0x00 );
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return sample_count;
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}
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/*******************************************************************
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Generate samples for the tape image
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********************************************************************/
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static int cgenie_cas_fill_wave(INT16 *buffer, int sample_count, UINT8 *bytes)
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{
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return cgenie_handle_cas( buffer, bytes );
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}
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/*******************************************************************
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Calculate the number of samples needed for this tape image
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********************************************************************/
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static int cgenie_cas_to_wav_size(const UINT8 *casdata, int caslen)
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{
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cas_size = caslen;
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return cgenie_handle_cas( NULL, casdata );
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}
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static const struct CassetteLegacyWaveFiller cgenie_cas_legacy_fill_wave =
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{
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cgenie_cas_fill_wave, /* fill_wave */
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-1, /* chunk_size */
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0, /* chunk_samples */
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cgenie_cas_to_wav_size, /* chunk_sample_calc */
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2400, /* sample_frequency */
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0, /* header_samples */
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0 /* trailer_samples */
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};
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static casserr_t cgenie_cas_identify(cassette_image *cassette, struct CassetteOptions *opts)
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{
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return cassette_legacy_identify(cassette, opts, &cgenie_cas_legacy_fill_wave);
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}
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static casserr_t cgenie_cas_load(cassette_image *cassette)
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{
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return cassette_legacy_construct(cassette, &cgenie_cas_legacy_fill_wave);
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}
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static const struct CassetteFormat cgenie_cas_format =
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{
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"cas",
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cgenie_cas_identify,
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cgenie_cas_load,
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NULL
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};
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CASSETTE_FORMATLIST_START(cgenie_cassette_formats)
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CASSETTE_FORMAT(cgenie_cas_format)
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CASSETTE_FORMATLIST_END
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