diff options
Diffstat (limited to 'src/lib/formats/x1_tap.cpp')
-rw-r--r-- | src/lib/formats/x1_tap.cpp | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/src/lib/formats/x1_tap.cpp b/src/lib/formats/x1_tap.cpp new file mode 100644 index 00000000000..5cf6f9fef94 --- /dev/null +++ b/src/lib/formats/x1_tap.cpp @@ -0,0 +1,139 @@ +// 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 <assert.h> + +#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* buffer, UINT8 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* buffer, const UINT8* 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 *casdata, int caslen) +{ + UINT32 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 *buffer, int sample_count, UINT8 *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 casserr_t x1_cas_identify(cassette_image *cassette, struct CassetteOptions *opts) +{ + return cassette_legacy_identify(cassette, opts, &x1_legacy_fill_wave); +} + + + +static casserr_t 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, + NULL +}; + +CASSETTE_FORMATLIST_START(x1_cassette_formats) + CASSETTE_FORMAT(x1_cassette_format) +CASSETTE_FORMATLIST_END |