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-rw-r--r--src/lib/formats/h8_cas.cpp96
1 files changed, 96 insertions, 0 deletions
diff --git a/src/lib/formats/h8_cas.cpp b/src/lib/formats/h8_cas.cpp
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+++ b/src/lib/formats/h8_cas.cpp
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+// 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