// license:BSD-3-Clause // copyright-holders:Barry Rodewald /* * * Sharp X1 TAP image format * * "New" header format: * 0x00: Index - must be "TAPE" (4 bytes) * 0x04: Image title. (null-terminated string, 17 bytes) * 0x15: Reserved (5 bytes) * 0x1a: Write protect (bit 4, 1 byte) * 0x1b: Format (bit 0, 1 byte) * if bit 0 is high, uses "speed limit sampling method" * 0x1c: Sample rate, per bit (in Hz, 4 bytes) * 0x20: Tape data size, in bits (4 bytes) * 0x24: Tape position (4 bytes, usually 0) * 0x28: Tape data (data size / 8) * * "Old" header format: * 0x00: Sampling rate (4 bytes) * */ #include #include "x1_tap.h" #define WAVE_HIGH 0x5a9e #define WAVE_LOW -0x5a9e static int cas_size; static int samplerate; static int new_format; static int x1_fill_wave(int16_t* buffer, uint8_t data, int sample_pos) { int x; int sample_count = 0; // one byte = 8 samples for(x=0;x<8;x++) { if(buffer) buffer[sample_pos+x] = (data & (1 << (7-x))) ? WAVE_HIGH : WAVE_LOW; sample_count++; } return sample_count; } static int x1_handle_tap(int16_t* buffer, const uint8_t* casdata) { int sample_count = 0; int data_pos = new_format ? 0x28 : 0x04; if (samplerate != 8000) { LOG_FORMATS("TAP: images that are not 8000Hz are not yet supported\n"); return -1; } while (sample_count < cas_size) { sample_count += x1_fill_wave(buffer, casdata[data_pos], sample_count); data_pos++; } return sample_count; } /******************************************************************* Calculate the number of samples needed for this tape image ********************************************************************/ static int x1_cas_to_wav_size (const uint8_t *casdata, int caslen) { uint32_t ret; if (!memcmp(casdata, "TAPE", 4)) // new TAP format { ret = casdata[0x20] | (casdata[0x21] << 8) | (casdata[0x22] << 16) | (casdata[0x23] << 24); cas_size = ret; samplerate = casdata[0x1c] | (casdata[0x1d] << 8) | (casdata[0x1e] << 16) | (casdata[0x1f] << 24); new_format = 1; } else // old TAP format { ret = (caslen - 4) * 8; // each byte = 8 samples cas_size = ret; samplerate = casdata[0x00] | (casdata[0x01] << 8) | (casdata[0x02] << 16) | (casdata[0x03] << 24); new_format = 0; } return ret; } /******************************************************************* Generate samples for the tape image ********************************************************************/ static int x1_cas_fill_wave(int16_t *buffer, int sample_count, uint8_t *bytes) { return x1_handle_tap(buffer,bytes); } static const struct CassetteLegacyWaveFiller x1_legacy_fill_wave = { x1_cas_fill_wave, /* fill_wave */ -1, /* chunk_size */ 0, /* chunk_samples */ x1_cas_to_wav_size, /* chunk_sample_calc */ 8000, /* sample_frequency */ 0, /* header_samples */ 0 /* trailer_samples */ }; static cassette_image::error x1_cas_identify(cassette_image *cassette, struct CassetteOptions *opts) { return cassette_legacy_identify(cassette, opts, &x1_legacy_fill_wave); } static cassette_image::error x1_cas_load(cassette_image *cassette) { return cassette_legacy_construct(cassette, &x1_legacy_fill_wave); } static const struct CassetteFormat x1_cassette_format = { "tap", x1_cas_identify, x1_cas_load, nullptr }; CASSETTE_FORMATLIST_START(x1_cassette_formats) CASSETTE_FORMAT(x1_cassette_format) CASSETTE_FORMATLIST_END