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-rw-r--r--trunk/src/lib/formats/trs_cas.c134
1 files changed, 134 insertions, 0 deletions
diff --git a/trunk/src/lib/formats/trs_cas.c b/trunk/src/lib/formats/trs_cas.c
new file mode 100644
index 00000000000..dac68647699
--- /dev/null
+++ b/trunk/src/lib/formats/trs_cas.c
@@ -0,0 +1,134 @@
+/********************************************************************
+
+Support for TRS80 .cas cassette images
+
+********************************************************************/
+
+#include "formats/trs_cas.h"
+
+#define SILENCE 0
+#define SMPLO -32768
+#define SMPHI 32767
+
+
+static int cas_size;
+
+
+/*******************************************************************
+ Generate one high-low cycle of sample data
+********************************************************************/
+INLINE int trs80l2_cas_cycle(INT16 *buffer, int sample_pos, int silence, int high, int low)
+{
+ int i = 0;
+
+ if ( buffer )
+ {
+ while( i < silence )
+ {
+ buffer[ sample_pos + i ] = SILENCE;
+ i++;
+ }
+ while( i < silence + high)
+ {
+ buffer[ sample_pos + i ] = SMPHI;
+ i++;
+ }
+
+ while( i < silence + high + low )
+ {
+ buffer[ sample_pos + i ] = SMPLO;
+ i++;
+ }
+ }
+ return silence + high + low;
+}
+
+
+static int trs80l2_handle_cas(INT16 *buffer, const UINT8 *casdata)
+{
+ int data_pos, sample_count;
+
+ data_pos = 0;
+ sample_count = 0;
+
+ while( data_pos < cas_size )
+ {
+ UINT8 data = casdata[data_pos];
+ int i;
+
+ for ( i = 0; i < 8; i++ )
+ {
+ /* Signal code */
+ sample_count += trs80l2_cas_cycle( buffer, sample_count, 33, 6, 6 );
+
+ /* Bit code */
+ if ( data & 0x80 )
+ sample_count += trs80l2_cas_cycle( buffer, sample_count, 33, 6, 6 );
+ else
+ sample_count += trs80l2_cas_cycle( buffer, sample_count, 33 + 6 + 6, 0, 0 );
+
+ data <<= 1;
+ }
+
+ data_pos++;
+ }
+ return sample_count;
+}
+
+
+/*******************************************************************
+ Generate samples for the tape image
+********************************************************************/
+static int trs80l2_cas_fill_wave(INT16 *buffer, int sample_count, UINT8 *bytes)
+{
+ return trs80l2_handle_cas( buffer, bytes );
+}
+
+
+/*******************************************************************
+ Calculate the number of samples needed for this tape image
+********************************************************************/
+static int trs80l2_cas_to_wav_size(const UINT8 *casdata, int caslen)
+{
+ cas_size = caslen;
+
+ return trs80l2_handle_cas( NULL, casdata );
+}
+
+static const struct CassetteLegacyWaveFiller trs80l2_cas_legacy_fill_wave =
+{
+ trs80l2_cas_fill_wave, /* fill_wave */
+ -1, /* chunk_size */
+ 0, /* chunk_samples */
+ trs80l2_cas_to_wav_size, /* chunk_sample_calc */
+ 44100, /* sample_frequency */
+ 0, /* header_samples */
+ 0 /* trailer_samples */
+};
+
+
+static casserr_t trs80l2_cas_identify(cassette_image *cassette, struct CassetteOptions *opts)
+{
+ return cassette_legacy_identify(cassette, opts, &trs80l2_cas_legacy_fill_wave);
+}
+
+
+static casserr_t trs80l2_cas_load(cassette_image *cassette)
+{
+ return cassette_legacy_construct(cassette, &trs80l2_cas_legacy_fill_wave);
+}
+
+
+static const struct CassetteFormat trs80l2_cas_format =
+{
+ "cas",
+ trs80l2_cas_identify,
+ trs80l2_cas_load,
+ NULL
+};
+
+
+CASSETTE_FORMATLIST_START(trs80l2_cassette_formats)
+ CASSETTE_FORMAT(trs80l2_cas_format)
+CASSETTE_FORMATLIST_END
+