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author | 2015-11-08 12:56:12 +0100 | |
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committer | 2015-11-08 12:56:12 +0100 | |
commit | 7c19aac60e12d6f5ea301bdb34d7826a01e0b06f (patch) | |
tree | f310d86aa2c6bfc19d115307dedde4eb0cd52dad /src/lib/formats/sol_cas.cpp | |
parent | a57b46ae933badd7441ce1644711dbb851e2b504 (diff) |
Rename *.c -> *.cpp in our source (nw)
Diffstat (limited to 'src/lib/formats/sol_cas.cpp')
-rw-r--r-- | src/lib/formats/sol_cas.cpp | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/src/lib/formats/sol_cas.cpp b/src/lib/formats/sol_cas.cpp new file mode 100644 index 00000000000..26f1bdccf00 --- /dev/null +++ b/src/lib/formats/sol_cas.cpp @@ -0,0 +1,379 @@ +// license:BSD-3-Clause +// copyright-holders:Robbbert +/******************************************************************** + +Support for SOL-20 cassette images + + +SOL20 tapes consist of these sections: +1. A high tone whenever idle +2. A header +3. The data, in blocks of 256 bytes plus a CRC byte +4. The last block may be shorter, depending on the number of bytes + left to save. + +Each byte has 1 start bit, 8 data bits (0-7), 2 stop bits. + +The default speed is 1200 baud, which is what we emulate here. +A high bit is 1 cycle of 1200 Hz, while a low bit is half a cycle +of 600 Hz. + +Formats: +SVT - The full explanation may be found on the Solace web site, + however this is a summary of what we support. + C (carrier) time in decaseconds + D (data bytes) in ascii text + H (header) tape header info + Multiple programs + Unsupported: + B (set baud rate) B 300 or B 1200 + F load ENT file + S (silence) time in decaseconds + bad-byte symbols + escaped characters + +********************************************************************/ + +#include <assert.h> + +#include "sol_cas.h" + +#define WAVEENTRY_LOW -32768 +#define WAVEENTRY_HIGH 32767 + +#define SOL20_WAV_FREQUENCY 4800 + +// image size +static UINT32 sol20_image_size; +static bool level; +static UINT8 sol20_cksm_byte; +static UINT32 sol20_byte_num; +static UINT8 sol20_header[16]; + +static int sol20_put_samples(INT16 *buffer, int sample_pos, int count) +{ + if (buffer) + { + for (int i=0; i<count; i++) + buffer[sample_pos + i] = level ? WAVEENTRY_LOW : WAVEENTRY_HIGH; + + level ^= 1; + } + + return count; +} + +static int sol20_output_bit(INT16 *buffer, int sample_pos, bool bit) +{ + int samples = 0; + + if (bit) + { + samples += sol20_put_samples(buffer, sample_pos + samples, 2); + samples += sol20_put_samples(buffer, sample_pos + samples, 2); + } + else + { + samples += sol20_put_samples(buffer, sample_pos + samples, 4); + } + + return samples; +} + +static int sol20_output_byte(INT16 *buffer, int sample_pos, UINT8 byte) +{ + int samples = 0; + UINT8 i; + + /* start */ + samples += sol20_output_bit (buffer, sample_pos + samples, 0); + + /* data */ + for (i = 0; i<8; i++) + samples += sol20_output_bit (buffer, sample_pos + samples, (byte >> i) & 1); + + /* stop */ + for (i = 0; i<2; i++) + samples += sol20_output_bit (buffer, sample_pos + samples, 1); + + return samples; +} + +// Calculate checksum +static UINT8 sol20_calc_cksm(UINT8 cksm, UINT8 data) +{ + data -= cksm; + cksm = data; + data ^= cksm; + data ^= 0xff; + data -= cksm; + return data; +} + +// Ignore remainder of line +static void sol20_scan_to_eol(const UINT8 *bytes) +{ + bool t = 1; + while (t) + { + if (sol20_byte_num >= sol20_image_size) + { + sol20_byte_num = 0; + t = 0; + } + else + if (bytes[sol20_byte_num] == 0x0d) + t = 0; + else + sol20_byte_num++; + } +} + +// skip spaces and symbols looking for a hex digit +static void sol20_scan_to_hex(const UINT8 *bytes) +{ + bool t = 1; + while (t) + { + if (sol20_byte_num >= sol20_image_size) + { + sol20_byte_num = 0; + t = 0; + } + else + { + UINT8 chr = bytes[sol20_byte_num]; + if (chr == 0x0d) + t = 0; + else + if (((chr >= '0') && (chr <= '9')) || ((chr >= 'A') && (chr <= 'F'))) + t = 0; + else + sol20_byte_num++; + } + } +} + +// Turn n digits into hex +static int sol20_read_hex(const UINT8 *bytes, UINT8 numdigits) +{ + int data = 0; + UINT8 i,chr; + + for (i = 0; i < numdigits; i++) + { + chr = bytes[sol20_byte_num]; + if ((chr >= '0') && (chr <= '9')) + { + data = (data << 4) | (chr-48); + sol20_byte_num++; + } + else + if ((chr >= 'A') && (chr <= 'F')) + { + data = (data << 4) | (chr-55); + sol20_byte_num++; + } + else + i = numdigits; + } + return data; +} + +// Turn digits into decimal +static int sol20_read_dec(const UINT8 *bytes) +{ + int data = 0; + + while ((bytes[sol20_byte_num] >= '0') && (bytes[sol20_byte_num] <= '9')) + { + data = data*10 + bytes[sol20_byte_num] - 48; + sol20_byte_num++; + } + + return data; +} + +static int sol20_handle_cassette(INT16 *buffer, const UINT8 *bytes) +{ + UINT32 sample_count = 0; + UINT32 i = 0,t = 0; + UINT8 c = 0; + sol20_byte_num = 1; + bool process_d = 0; + UINT16 length = 0; + + // 1st line of file must say SVT + if ((bytes[0] == 'S') && (bytes[1] == 'V') && (bytes[2] == 'T')) + { } + else + return sample_count; + + // ignore remainder of line + sol20_scan_to_eol(bytes); + + // process the commands + while (sol20_byte_num) + { + sol20_byte_num+=2; // bump to start of next line + UINT8 chr = bytes[sol20_byte_num]; // Get command + if (sol20_byte_num >= sol20_image_size) + sol20_byte_num = 0; + else + { + switch (chr) + { + case 0x0d: + break; + case 'C': // carrier + { + if (c) // if this is the next file, clean up after the previous one + { + sample_count += sol20_output_byte(buffer, sample_count, sol20_cksm_byte); // final checksum if needed + c = 0; + } + + sol20_byte_num+=2; // bump to parameter + t = sol20_read_dec(bytes) * 140; // convert 10th of seconds to number of ones + for (i = 0; i < t; i++) + sample_count += sol20_output_bit(buffer, sample_count, 1); + sol20_scan_to_eol(bytes); + break; + } + case 'H': // header + { + if (c) // if this is the next file, clean up after the previous one + { + sample_count += sol20_output_byte(buffer, sample_count, sol20_cksm_byte); // final checksum if needed + c = 0; + } + + sol20_byte_num+=2; // bump to file name + sol20_header[0] = bytes[sol20_byte_num++]; + sol20_header[1] = bytes[sol20_byte_num++]; + sol20_header[2] = bytes[sol20_byte_num++]; + sol20_header[3] = bytes[sol20_byte_num++]; + sol20_header[4] = bytes[sol20_byte_num++]; + sol20_header[5] = 0; + sol20_scan_to_hex(bytes); // bump to file type + sol20_header[6] = sol20_read_hex(bytes, 2); + sol20_scan_to_hex(bytes); // bump to length + length = sol20_read_hex(bytes, 4); + sol20_header[7] = length; + sol20_header[8] = length >> 8; + sol20_scan_to_hex(bytes); // bump to load-address + i = sol20_read_hex(bytes, 4); + sol20_header[9] = i; + sol20_header[10] = i >> 8; + sol20_scan_to_hex(bytes); // bump to exec-address + i = sol20_read_hex(bytes, 4); + sol20_header[11] = i; + sol20_header[12] = i >> 8; + sol20_header[13] = 0; + sol20_header[14] = 0; + sol20_header[15] = 0; + sol20_cksm_byte = 0; + for (i = 0; i < 16; i++) + sol20_cksm_byte = sol20_calc_cksm(sol20_cksm_byte, sol20_header[i]); + // write leader + for (i = 0; i < 100; i++) + sample_count += sol20_output_byte(buffer, sample_count, 0); + // write SOH + sample_count += sol20_output_byte(buffer, sample_count, 1); + // write Header + for (i = 0; i < 16; i++) + sample_count += sol20_output_byte(buffer, sample_count, sol20_header[i]); + // write checksum + sample_count += sol20_output_byte(buffer, sample_count, sol20_cksm_byte); + + sol20_cksm_byte = 0; + process_d = 1; + sol20_scan_to_eol(bytes); + break; + } + case 'D': // data + { + sol20_byte_num+=2; // bump to first byte + while ((bytes[sol20_byte_num] != 0x0d) && sol20_byte_num && process_d) + { + t = sol20_read_hex(bytes, 2); + sample_count += sol20_output_byte(buffer, sample_count, t); + sol20_cksm_byte = sol20_calc_cksm(sol20_cksm_byte, t); + c++; + length--; + if (!length) + process_d = 0; + if (!c) + { + sample_count += sol20_output_byte(buffer, sample_count, sol20_cksm_byte); + sol20_cksm_byte = 0; + } + sol20_scan_to_hex(bytes); + } + } + default: // everything else is ignored + sol20_scan_to_eol(bytes); + break; + } + } + } + + if (c) // reached the end of the svt file + sample_count += sol20_output_byte(buffer, sample_count, sol20_cksm_byte); // final checksum if needed + + return sample_count; +} + + +/******************************************************************* + Generate samples for the tape image +********************************************************************/ + +static int sol20_cassette_fill_wave(INT16 *buffer, int length, UINT8 *bytes) +{ + return sol20_handle_cassette(buffer, bytes); +} + +/******************************************************************* + Calculate the number of samples needed for this tape image +********************************************************************/ + +static int sol20_cassette_calculate_size_in_samples(const UINT8 *bytes, int length) +{ + sol20_image_size = length; + + return sol20_handle_cassette(NULL, bytes); +} + +static const struct CassetteLegacyWaveFiller sol20_legacy_fill_wave = +{ + sol20_cassette_fill_wave, /* fill_wave */ + -1, /* chunk_size */ + 0, /* chunk_samples */ + sol20_cassette_calculate_size_in_samples, /* chunk_sample_calc */ + SOL20_WAV_FREQUENCY, /* sample_frequency */ + 0, /* header_samples */ + 0 /* trailer_samples */ +}; + +static casserr_t sol20_cassette_identify(cassette_image *cassette, struct CassetteOptions *opts) +{ + return cassette_legacy_identify(cassette, opts, &sol20_legacy_fill_wave); +} + +static casserr_t sol20_cassette_load(cassette_image *cassette) +{ + return cassette_legacy_construct(cassette, &sol20_legacy_fill_wave); +} + +static const struct CassetteFormat sol20_cassette_image_format = +{ + "svt", + sol20_cassette_identify, + sol20_cassette_load, + NULL +}; + +CASSETTE_FORMATLIST_START(sol20_cassette_formats) + CASSETTE_FORMAT(sol20_cassette_image_format) +CASSETTE_FORMATLIST_END |