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Add the skeleton of the Brother GCR decoder.

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This commit is contained in:
David Given
2018-10-18 01:44:59 +02:00
parent 607bb141b3
commit 3dec0ac54d
6 changed files with 226 additions and 18 deletions
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1
Makefile
View File

@@ -12,6 +12,7 @@ SRCS = \
cmd_read.c \
cmd_write.c \
cmd_mfmdecode.c \
cmd_brotherdecode.c \
cmd_testpattern.c \
cmd_fluxdump.c \
cmd_calibrate.c \

212
cmd_brotherdecode.c Normal file
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@@ -0,0 +1,212 @@
#include "globals.h"
#include "sql.h"
#include <unistd.h>
#include <string.h>
#define CLOCK_LOCK_BOOST 6 /* arbitrary */
#define CLOCK_LOCK_DECAY 1 /* arbitrary */
#define CLOCK_DETECTOR_AMPLITUDE_THRESHOLD 60 /* arbi4rary */
#define CLOCK_ERROR_BOUNDS 0.25
#define IAM 0xFC /* start-of-track record */
#define IAM_LEN 4
#define IDAM 0xFE /* sector header */
#define IDAM_LEN 10
#define DAM1 0xF8 /* sector data (type 1) */
#define DAM2 0xFB /* sector data (type 2) */
#define DAM_LEN 6 /* plus user data */
/* Length of a DAM record is determined by the previous sector header. */
static const char* inputfilename = NULL;
static const char* outputfilename = NULL;
static bool verbose = false;
static sqlite3* indb;
static sqlite3* outdb;
static int cursor;
static nanoseconds_t elapsed_time;
static uint8_t outputbuffer[20*1024];
static int outputbufferpos;
static uint8_t outputfifo = 0;
static int bitcount = 0;
static bool phase = false;
static void syntax_error(void)
{
fprintf(stderr,
"syntax: fluxclient mfmdecode <options>:\n"
" -i <filename> input filename (.flux)\n"
" -o <filename> output filename (.rec)\n"
" -v verbose decoding\n"
);
exit(1);
}
static char* const* parse_options(char* const* argv)
{
for (;;)
{
switch (getopt(countargs(argv), argv, "+i:o:v"))
{
case -1:
return argv + optind - 1;
case 'i':
inputfilename = optarg;
break;
case 'o':
outputfilename = optarg;
break;
case 'v':
verbose = true;
break;
default:
syntax_error();
}
}
}
static void close_files(void)
{
if (indb)
sqlite3_close(indb);
if (outdb)
sqlite3_close(outdb);
}
static void open_files(void)
{
indb = sql_open(inputfilename, SQLITE_OPEN_READONLY);
outdb = sql_open(outputfilename, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
sql_prepare_record(outdb);
atexit(close_files);
}
static void write_bit(bool bit)
{
outputfifo = (outputfifo << 1) | bit;
bitcount++;
if (bitcount == 8)
{
outputbuffer[outputbufferpos++] = outputfifo;
bitcount = 0;
}
}
static void log_record(void)
{
if (verbose)
printf("\n % 8.3fms [0x%05x] ",
(double)elapsed_time / 1e6, cursor);
else
putchar('.');
}
static void decode_track_cb(int track, int side, const struct fluxmap* fluxmap)
{
printf("Track %02d side %d: ", track, side);
nanoseconds_t clock_period = fluxmap_guess_clock(fluxmap);
printf("% 4.1fus ", (double)clock_period/(double)1000);
struct encoding_buffer* decoded = fluxmap_decode(fluxmap, clock_period);
for (int i=0; i<decoded->length_pulses; i++)
putchar(decoded->bitmap[i] ? 'X' : '.');
#if 0
cursor = 0;
uint64_t inputfifo = 0;
bool reading = false;
int record = 0;
while (cursor < decoded->length_pulses)
{
elapsed_time = cursor * decoded->pulselength_ns;
bool bit = decoded->bitmap[cursor++];
inputfifo = (inputfifo << 1) | bit;
/*
* The IAM record, which is the first one on the disk (and is optional), uses
* a distorted 0xC2 0xC2 0xC2 marker to identify it. Unfortunately, if this is
* shifted out of phase, it becomes a legal encoding, so if we're looking at
* real data we can't honour this.
*
* 0xC2 is:
* data: 1 1 0 0 0 0 1 0
* mfm: 01 01 00 10 10 10 01 00 = 0x5254
* special: 01 01 00 10 00 10 01 00 = 0x5224
* ^^^^
* shifted: 10 10 01 00 01 00 10 0. = legal, and might happen in real data
*
* Therefore, when we've read the marker, the input fifo will contain
* 0xXXXX522252225222.
*
* All other records use 0xA1 as a marker:
*
* 0xA1 is:
* data: 1 0 1 0 0 0 0 1
* mfm: 01 00 01 00 10 10 10 01 = 0x44A9
* special: 01 00 01 00 10 00 10 01 = 0x4489
* ^^^^^
* shifted: 10 00 10 01 00 01 00 1
*
* When this is shifted out of phase, we get an illegal encoding (you
* can't do 10 00). So, if we ever see 0x448944894489 in the input
* fifo, we know we've landed at the beginning of a new record.
*/
uint64_t masked = inputfifo & 0xFFFFFFFFFFFFLL;
if ((!reading && (masked == 0x522452245224LL)) || (masked == 0x448944894489LL))
{
log_record();
if (reading)
sql_write_record(outdb, track, side, record++, outputbuffer, outputbufferpos);
if (!reading)
memcpy(outputbuffer, "\xc2\xc2\xc2", 3);
else
memcpy(outputbuffer, "\xa1\xa1\xa1", 3);
reading = true;
outputbufferpos = 3;
bitcount = 0;
phase = 0;
}
else if (reading)
{
if (phase)
write_bit(bit);
phase = !phase;
}
}
if (reading)
sql_write_record(outdb, track, side, record++, outputbuffer, outputbufferpos);
if (verbose)
printf("\n ");
printf(" = %d records\n", record);
#endif
}
void cmd_brotherdecode(char* const* argv)
{
argv = parse_options(argv);
if (countargs(argv) != 1)
syntax_error();
if (!inputfilename)
error("you must supply a filename to read from");
if (!outputfilename)
error("you must supply a filename to write to");
open_files();
sql_stmt(outdb, "BEGIN");
sql_stmt(outdb, "DELETE FROM records");
sql_for_all_flux_data(indb, decode_track_cb);
sql_stmt(outdb, "COMMIT");
}

27
cmd_fluxdump.c
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@@ -6,7 +6,6 @@ static const char* input_filename = NULL;
static const char* output_filename = NULL;
static int track = 0;
static int side = 0;
static int resolution_ns = NS_PER_TICK;
static sqlite3* db;
static void syntax_error(void)
@@ -18,7 +17,6 @@ static void syntax_error(void)
" -t <track> track to dump\n"
" -0 dump side 0\n"
" -1 dump side 1\n"
" -r <resolution> time per sample in ns (default: one tick)\n"
);
exit(1);
}
@@ -27,7 +25,7 @@ static char* const* parse_options(char* const* argv)
{
for (;;)
{
switch (getopt(countargs(argv), argv, "+i:o:t:01r:L"))
switch (getopt(countargs(argv), argv, "+i:o:t:01:L"))
{
case -1:
return argv + optind - 1;
@@ -50,10 +48,6 @@ static char* const* parse_options(char* const* argv)
case '1':
side = 1;
break;
case 'r':
resolution_ns = atoi(optarg);
break;
default:
@@ -82,8 +76,6 @@ void cmd_fluxdump(char* const* argv)
error("you must supply a filename to read from");
if (!output_filename)
error("you must supply a filename to write to");
if (resolution_ns < NS_PER_TICK)
error("resolution too fine (minimum: %dns)", NS_PER_TICK);
open_file();
struct fluxmap* fluxmap = sql_read_flux(db, track, side);
@@ -91,21 +83,20 @@ void cmd_fluxdump(char* const* argv)
error("no data for that track in the file");
printf("Length: %d ms\n", fluxmap->length_us / 1000);
int length_r = fluxmap->length_us * 1000 / resolution_ns;
printf("Output size: %d bytes\n", length_r);
int length_ticks = fluxmap->length_us * TICKS_PER_US;
printf("Output size: %d bytes\n", length_ticks);
uint8_t* buffer = calloc(1, length_r);
int cursor_ns = 0;
uint8_t* buffer = calloc(1, length_ticks);
int cursor_ticks = 0;
for (int i=0; i<fluxmap->bytes; i++)
{
uint8_t t = fluxmap->intervals[i];
cursor_ns += t * NS_PER_TICK / resolution_ns;
if (cursor_ns < length_r)
buffer[cursor_ns] = 0x7f;
cursor_ticks += fluxmap->intervals[i];
if (cursor_ticks < length_ticks)
buffer[cursor_ticks] = 0x7f;
}
FILE* fp = fopen(output_filename, "wb");
fwrite(buffer, length_r, 1, fp);
fwrite(buffer, length_ticks, 1, fp);
fclose(fp);
free(buffer);
}

1
globals.h
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@@ -71,6 +71,7 @@ extern void cmd_usbbench(char* const* argv);
extern void cmd_read(char* const* argv);
extern void cmd_write(char* const* argv);
extern void cmd_mfmdecode(char* const* argv);
extern void cmd_brotherdecode(char* const* argv);
extern void cmd_testpattern(char* const* argv);
extern void cmd_fluxdump(char* const* argv);
extern void cmd_calibrate(char* const* argv);

2
main.c
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@@ -76,6 +76,8 @@ int main(int argc, char* const* argv)
cmd_write(argv);
else if (strcmp(argv[0], "mfmdecode") == 0)
cmd_mfmdecode(argv);
else if (strcmp(argv[0], "brotherdecode") == 0)
cmd_brotherdecode(argv);
else if (strcmp(argv[0], "testpattern") == 0)
cmd_testpattern(argv);
else if (strcmp(argv[0], "fluxdump") == 0)

1
protocol.h
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@@ -34,6 +34,7 @@ enum
};
#define NS_PER_TICK ((double)1000000000 / (double)TICK_FREQUENCY)
#define US_PER_TICK ((double)1000000 / (double)TICK_FREQUENCY)
enum
{