// license:BSD-3-Clause // copyright-holders:Robbbert,Mark Garlanger /******************************************************************** Support for Heathkit H8/H88 H8T cassette images Standard Kansas City format (300 baud) TODO - investigate 1200 buad support, H8 should support it, but H88 does not. We output a leader, followed by the contents of the H8T file. ********************************************************************/ #include "h8_cas.h" #include "coretmpl.h" // BIT namespace { constexpr double ONE_FREQ = 1200.0; constexpr double ONE_FREQ_VARIANCE = 300.0; constexpr double ZERO_FREQ = 2400.0; constexpr double ZERO_FREQ_VARIANCE = 600.0; const cassette_image::Modulation heath_h8t_modulation = { cassette_image::MODULATION_SINEWAVE, ONE_FREQ - ONE_FREQ_VARIANCE, ONE_FREQ, ONE_FREQ + ONE_FREQ_VARIANCE, ZERO_FREQ - ZERO_FREQ_VARIANCE, ZERO_FREQ, ZERO_FREQ + ZERO_FREQ_VARIANCE }; cassette_image::error heath_h8t_identify(cassette_image *cassette, cassette_image::Options *opts) { return cassette->modulation_identify(heath_h8t_modulation, opts); } cassette_image::error heath_h8t_load(cassette_image *cassette) { cassette_image::error err = cassette_image::error::SUCCESS; uint64_t image_size = cassette->image_size(); double time_index = 0.0; double time_displacement; auto const MODULATE = [&cassette, &err, &time_index, &time_displacement] (unsigned value) { for (int i = 0; (i < (value ? 8 : 4)); i++) { err = cassette->put_modulated_data_bit(0, time_index, value, heath_h8t_modulation, &time_displacement); if (cassette_image::error::SUCCESS == err) time_index += time_displacement; else return; } }; // leader - 1 second while ((cassette_image::error::SUCCESS == err) && (time_index < 1.0)) MODULATE(1); for (uint64_t image_pos = 0; (cassette_image::error::SUCCESS == err) && (image_pos < image_size); image_pos++) { uint8_t data = cassette->image_read_byte(image_pos); // start bit MODULATE(0); // data bits for (int bit = 0; (cassette_image::error::SUCCESS == err) && (bit < 8); bit++) MODULATE(util::BIT(data, bit)); // stop bit if (cassette_image::error::SUCCESS == err) MODULATE(1); } return err; } const cassette_image::Format heath_h8t_format = { "h8t", heath_h8t_identify, heath_h8t_load, nullptr }; } CASSETTE_FORMATLIST_START( h8_cassette_formats ) CASSETTE_FORMAT( heath_h8t_format ) CASSETTE_FORMATLIST_END