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+// license:BSD-3-Clause
+// copyright-holders:Robbbert
+/********************************************************************
+
+Support for Sanyo PHC25 cassette images
+
+phc images consist of 5 sections
+1. 10 A5 bytes
+2. 6 name of the program
+3. The basic program file. Each line is delimited by null. This
+ section is terminated by 3 nulls (1 of them for the preceeding
+ line, the other 2 indicate the end).
+4. The line numbers and pointers to them. It ends at the image size-1
+5. A 1-byte trailer of FF which we do not pass on
+
+Each byte after conversion becomes a start bit, bit 0,1,etc to 7,
+then 4 stop bits.
+
+An actual tape consists of 6 sections
+a. 2.656secs of silence
+b. 4.862secs of high bits
+c. The header which is parts 1 and 2 above
+d. 0.652secs of high bits
+e. The main program which is parts 3 and 4 above
+f. 1.771secs of silence
+
+We don't emulate the full silence and high-bits periods, only just
+enough to make it work.
+
+********************************************************************/
+
+#include <assert.h>
+
+#include "phc25_cas.h"
+
+#define WAVEENTRY_LOW -32768
+#define WAVEENTRY_HIGH 32767
+
+#define PHC25_WAV_FREQUENCY 9600
+#define PHC25_HEADER_BYTES 16
+
+// image size
+static int phc25_image_size;
+
+static int phc25_put_samples(INT16 *buffer, int sample_pos, int count, int level)
+{
+ if (buffer)
+ {
+ for (int i=0; i<count; i++)
+ buffer[sample_pos + i] = level;
+ }
+
+ return count;
+}
+
+static int phc25_output_bit(INT16 *buffer, int sample_pos, bool bit)
+{
+ int samples = 0;
+
+ if (bit)
+ {
+ samples += phc25_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_LOW);
+ samples += phc25_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_HIGH);
+ samples += phc25_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_LOW);
+ samples += phc25_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_HIGH);
+ }
+ else
+ {
+ samples += phc25_put_samples(buffer, sample_pos + samples, 4, WAVEENTRY_LOW);
+ samples += phc25_put_samples(buffer, sample_pos + samples, 4, WAVEENTRY_HIGH);
+ }
+
+ return samples;
+}
+
+static int phc25_output_byte(INT16 *buffer, int sample_pos, UINT8 byte)
+{
+ int samples = 0;
+ UINT8 i;
+
+ /* start */
+ samples += phc25_output_bit (buffer, sample_pos + samples, 0);
+
+ /* data */
+ for (i = 0; i<8; i++)
+ samples += phc25_output_bit (buffer, sample_pos + samples, (byte >> i) & 1);
+
+ /* stop */
+ for (i = 0; i<4; i++)
+ samples += phc25_output_bit (buffer, sample_pos + samples, 1);
+
+ return samples;
+}
+
+static int phc25_handle_cassette(INT16 *buffer, const UINT8 *bytes)
+{
+ UINT32 sample_count = 0;
+ UINT32 byte_count = 0;
+ UINT32 i;
+
+ // silence
+// sample_count += phc25_put_samples(buffer, 6640, 2, WAVEENTRY_HIGH);
+
+ /* start */
+// for (i=0; i<12155; i++)
+ for (i=0; i<2155; i++)
+ sample_count += phc25_output_bit(buffer, sample_count, 1);
+
+ /* header */
+ for (int i=0; i<PHC25_HEADER_BYTES; i++)
+ sample_count += phc25_output_byte(buffer, sample_count, bytes[i]);
+
+ byte_count = PHC25_HEADER_BYTES;
+
+ /* pause */
+ for (i=0; i<1630; i++)
+ sample_count += phc25_output_bit(buffer, sample_count, 1);
+
+ /* data */
+ for (i=byte_count; i<phc25_image_size-1; i++)
+ sample_count += phc25_output_byte(buffer, sample_count, bytes[i]);
+
+ // silence
+ sample_count += phc25_put_samples(buffer, 1000, 2, WAVEENTRY_HIGH);
+
+ return sample_count;
+}
+
+
+/*******************************************************************
+ Generate samples for the tape image
+********************************************************************/
+
+static int phc25_cassette_fill_wave(INT16 *buffer, int length, UINT8 *bytes)
+{
+ return phc25_handle_cassette(buffer, bytes);
+}
+
+/*******************************************************************
+ Calculate the number of samples needed for this tape image
+********************************************************************/
+
+static int phc25_cassette_calculate_size_in_samples(const UINT8 *bytes, int length)
+{
+ phc25_image_size = length;
+
+ return phc25_handle_cassette(NULL, bytes);
+}
+
+static const struct CassetteLegacyWaveFiller phc25_legacy_fill_wave =
+{
+ phc25_cassette_fill_wave, /* fill_wave */
+ -1, /* chunk_size */
+ 0, /* chunk_samples */
+ phc25_cassette_calculate_size_in_samples, /* chunk_sample_calc */
+ PHC25_WAV_FREQUENCY, /* sample_frequency */
+ 0, /* header_samples */
+ 0 /* trailer_samples */
+};
+
+static casserr_t phc25_cassette_identify(cassette_image *cassette, struct CassetteOptions *opts)
+{
+ return cassette_legacy_identify(cassette, opts, &phc25_legacy_fill_wave);
+}
+
+static casserr_t phc25_cassette_load(cassette_image *cassette)
+{
+ return cassette_legacy_construct(cassette, &phc25_legacy_fill_wave);
+}
+
+static const struct CassetteFormat phc25_cassette_image_format =
+{
+ "phc",
+ phc25_cassette_identify,
+ phc25_cassette_load,
+ NULL
+};
+
+CASSETTE_FORMATLIST_START(phc25_cassette_formats)
+ CASSETTE_FORMAT(phc25_cassette_image_format)
+CASSETTE_FORMATLIST_END