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author | 2015-11-08 12:56:12 +0100 | |
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committer | 2015-11-08 12:56:12 +0100 | |
commit | 7c19aac60e12d6f5ea301bdb34d7826a01e0b06f (patch) | |
tree | f310d86aa2c6bfc19d115307dedde4eb0cd52dad /src/lib/formats/ace_tap.cpp | |
parent | a57b46ae933badd7441ce1644711dbb851e2b504 (diff) |
Rename *.c -> *.cpp in our source (nw)
Diffstat (limited to 'src/lib/formats/ace_tap.cpp')
-rw-r--r-- | src/lib/formats/ace_tap.cpp | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/src/lib/formats/ace_tap.cpp b/src/lib/formats/ace_tap.cpp new file mode 100644 index 00000000000..3479d6ba1f5 --- /dev/null +++ b/src/lib/formats/ace_tap.cpp @@ -0,0 +1,193 @@ +// license:BSD-3-Clause +// copyright-holders:Wilbert Pol +/******************************************************************** + +Support for Jupiter Ace .tap cassette images + +For more information see: +- http://www.jupiter-ace.co.uk/faq_ace_tap_format.html +- http://www.jupiter-ace.co.uk/doc_AceTapeFormat.html + +********************************************************************/ + +#include <assert.h> + +#include "ace_tap.h" + + +#define SMPLO -32768 +#define SILENCE 0 +#define SMPHI 32767 + + +static int cas_size; + + +/******************************************************************* + Generate one high-low cycle of sample data +********************************************************************/ +INLINE int ace_tap_cycle(INT16 *buffer, int sample_pos, int high, int low) +{ + int i = 0; + + if ( buffer ) + { + while( i < high) + { + buffer[ sample_pos + i ] = SMPHI; + i++; + } + + while( i < high + low ) + { + buffer[ sample_pos + i ] = SMPLO; + i++; + } + } + return high + low; +} + + +INLINE int ace_tap_silence(INT16 *buffer, int sample_pos, int samples) +{ + int i = 0; + + if ( buffer ) + { + while( i < samples ) + { + buffer[ sample_pos + i ] = SILENCE; + i++; + } + } + return samples; +} + + +INLINE int ace_tap_byte(INT16 *buffer, int sample_pos, UINT8 data) +{ + int i, samples; + + samples = 0; + for ( i = 0; i < 8; i++ ) + { + if ( data & 0x80 ) + samples += ace_tap_cycle( buffer, sample_pos + samples, 21, 22 ); + else + samples += ace_tap_cycle( buffer, sample_pos + samples, 10, 11 ); + + data <<= 1; + } + return samples; +} + + +static int ace_handle_tap(INT16 *buffer, const UINT8 *casdata) +{ + int data_pos, sample_count; + + /* Make sure the file starts with a valid header */ + if ( cas_size < 0x1C ) + return -1; + if ( casdata[0] != 0x1A || casdata[1] != 0x00 ) + return -1; + + data_pos = 0; + sample_count = 0; + + while( data_pos < cas_size ) + { + UINT16 block_size; + int i; + + /* Handle a block of tape data */ + block_size = casdata[data_pos] + ( casdata[data_pos + 1] << 8 ); + data_pos += 2; + + /* Make sure there are enough bytes left */ + if ( data_pos > cas_size ) + return -1; + + /* 2 seconds silence */ + sample_count += ace_tap_silence( buffer, sample_count, 2 * 44100 ); + + /* Add pilot tone samples: 4096 for header, 512 for data */ + for( i = ( block_size == 0x001A ) ? 4096 : 512; i; i-- ) + sample_count += ace_tap_cycle( buffer, sample_count, 27, 27 ); + + /* Sync samples */ + sample_count += ace_tap_cycle( buffer, sample_count, 8, 11 ); + + /* Output block type identification byte */ + sample_count += ace_tap_byte( buffer, sample_count, ( block_size != 0x001A ) ? 0xFF : 0x00 ); + + /* Data samples */ + for ( ; block_size ; data_pos++, block_size-- ) + sample_count += ace_tap_byte( buffer, sample_count, casdata[data_pos] ); + + /* End mark samples */ + sample_count += ace_tap_cycle( buffer, sample_count, 12, 57 ); + + /* 3 seconds silence */ + sample_count += ace_tap_silence( buffer, sample_count, 3 * 44100 ); + } + return sample_count; +} + + +/******************************************************************* + Generate samples for the tape image +********************************************************************/ +static int ace_tap_fill_wave(INT16 *buffer, int sample_count, UINT8 *bytes) +{ + return ace_handle_tap( buffer, bytes ); +} + + +/******************************************************************* + Calculate the number of samples needed for this tape image +********************************************************************/ +static int ace_tap_to_wav_size(const UINT8 *casdata, int caslen) +{ + cas_size = caslen; + + return ace_handle_tap( NULL, casdata ); +} + + +static const struct CassetteLegacyWaveFiller ace_legacy_fill_wave = +{ + ace_tap_fill_wave, /* fill_wave */ + -1, /* chunk_size */ + 0, /* chunk_samples */ + ace_tap_to_wav_size, /* chunk_sample_calc */ + 44100, /* sample_frequency */ + 0, /* header_samples */ + 0 /* trailer_samples */ +}; + + +static casserr_t ace_tap_identify(cassette_image *cassette, struct CassetteOptions *opts) +{ + return cassette_legacy_identify(cassette, opts, &ace_legacy_fill_wave); +} + + +static casserr_t ace_tap_load(cassette_image *cassette) +{ + return cassette_legacy_construct(cassette, &ace_legacy_fill_wave); +} + + +static const struct CassetteFormat ace_tap_format = +{ + "tap", + ace_tap_identify, + ace_tap_load, + NULL +}; + + +CASSETTE_FORMATLIST_START(ace_cassette_formats) + CASSETTE_FORMAT(ace_tap_format) +CASSETTE_FORMATLIST_END |