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-rw-r--r--trunk/src/lib/formats/ace_tap.c188
1 files changed, 188 insertions, 0 deletions
diff --git a/trunk/src/lib/formats/ace_tap.c b/trunk/src/lib/formats/ace_tap.c
new file mode 100644
index 00000000000..3cabe2e4ec4
--- /dev/null
+++ b/trunk/src/lib/formats/ace_tap.c
@@ -0,0 +1,188 @@
+/********************************************************************
+
+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 "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