mirror of
https://github.com/holub/mame
synced 2025-05-22 21:58:57 +03:00
136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
/*
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*
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* Sharp X1 TAP image format
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*
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* "New" header format:
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* 0x00: Index - must be "TAPE" (4 bytes)
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* 0x04: Image title. (null-terminated string, 17 bytes)
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* 0x15: Reserved (5 bytes)
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* 0x1a: Write protect (bit 4, 1 byte)
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* 0x1b: Format (bit 0, 1 byte)
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* if bit 0 is high, uses "speed limit sampling method"
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* 0x1c: Sample rate, per bit (in Hz, 4 bytes)
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* 0x20: Tape data size, in bits (4 bytes)
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* 0x24: Tape position (4 bytes, usually 0)
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* 0x28: Tape data (data size / 8)
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*
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* "Old" header format:
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* 0x00: Sampling rate (4 bytes)
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*
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*/
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#include "x1_tap.h"
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#define WAVE_HIGH 0x5a9e
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#define WAVE_LOW -0x5a9e
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static int cas_size;
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static int samplerate;
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static int new_format;
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static int x1_fill_wave(INT16* buffer, UINT8 data, int sample_pos)
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{
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int x;
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int sample_count = 0;
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// one byte = 8 samples
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for(x=0;x<8;x++)
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{
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if(buffer)
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buffer[sample_pos+x] = (data & (1 << (7-x))) ? WAVE_HIGH : WAVE_LOW;
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sample_count++;
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}
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return sample_count;
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}
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static int x1_handle_tap(INT16* buffer, const UINT8* casdata)
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{
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int sample_count = 0;
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int data_pos = new_format ? 0x28 : 0x04;
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if (samplerate != 8000)
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{
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LOG_FORMATS("TAP: images that are not 8000Hz are not yet supported\n");
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return -1;
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}
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while (sample_count < cas_size)
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{
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sample_count += x1_fill_wave(buffer, casdata[data_pos], sample_count);
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data_pos++;
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}
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return sample_count;
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}
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/*******************************************************************
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Calculate the number of samples needed for this tape image
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********************************************************************/
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static int x1_cas_to_wav_size (const UINT8 *casdata, int caslen)
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{
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UINT32 ret;
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if (!memcmp(casdata, "TAPE", 4)) // new TAP format
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{
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ret = casdata[0x20] | (casdata[0x21] << 8) | (casdata[0x22] << 16) | (casdata[0x23] << 24);
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cas_size = ret;
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samplerate = casdata[0x1c] | (casdata[0x1d] << 8) | (casdata[0x1e] << 16) | (casdata[0x1f] << 24);
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new_format = 1;
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}
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else // old TAP format
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{
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ret = (caslen - 4) * 8; // each byte = 8 samples
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cas_size = ret;
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samplerate = casdata[0x00] | (casdata[0x01] << 8) | (casdata[0x02] << 16) | (casdata[0x03] << 24);
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new_format = 0;
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}
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return ret;
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}
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/*******************************************************************
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Generate samples for the tape image
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********************************************************************/
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static int x1_cas_fill_wave(INT16 *buffer, int sample_count, UINT8 *bytes)
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{
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return x1_handle_tap(buffer,bytes);
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}
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static const struct CassetteLegacyWaveFiller x1_legacy_fill_wave =
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{
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x1_cas_fill_wave, /* fill_wave */
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-1, /* chunk_size */
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0, /* chunk_samples */
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x1_cas_to_wav_size, /* chunk_sample_calc */
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8000, /* sample_frequency */
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0, /* header_samples */
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0 /* trailer_samples */
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};
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static casserr_t x1_cas_identify(cassette_image *cassette, struct CassetteOptions *opts)
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{
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return cassette_legacy_identify(cassette, opts, &x1_legacy_fill_wave);
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}
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static casserr_t x1_cas_load(cassette_image *cassette)
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{
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return cassette_legacy_construct(cassette, &x1_legacy_fill_wave);
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}
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static const struct CassetteFormat x1_cassette_format = {
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"tap",
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x1_cas_identify,
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x1_cas_load,
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NULL
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};
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CASSETTE_FORMATLIST_START(x1_cassette_formats)
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CASSETTE_FORMAT(x1_cassette_format)
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CASSETTE_FORMATLIST_END
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