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garmin_parser: add support for compressed records and more debug output

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This turns out to have been another false turn: mis-parsing the FIT file
caused us to think it had compressed records.

So I spent much too much time trying to figure out how those compressed
records actually work.  This is the result.

It looks like the only difference between a compressed record and a
regular one is that the compressed record has a single-byte "this is the
record type and the time offset" field at the start.  That basically
avoids the need of then having a full 4-byte absolute time for such a
record.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2023-07-13 13:58:44 -07:00
parent 4aa70c9e2a
commit 147d3df635
1 changed files with 8 additions and 9 deletions
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17
src/garmin_parser.c
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@ -1144,14 +1144,6 @@ static const struct msg_desc *lookup_msg_desc(unsigned short msg, int local, con
return desc;
}
static int traverse_compressed(struct garmin_parser_t *garmin,
const unsigned char *data, unsigned int size,
unsigned char type, unsigned int time)
{
fprintf(stderr, "Compressed record for local type %d:\n", type);
return -1;
}
static int all_data_inval(const unsigned char *data, int base_type, int len)
{
int base_size = base_type_info[base_type].type_size;
@ -1413,10 +1405,17 @@ traverse_data(struct garmin_parser_t *garmin)
newtime += 0x20;
time = newtime;
len = traverse_compressed(garmin, data, datasize, type, time);
// Compressed records are like normal records
// with that added relative timestamp
DEBUG(garmin->base.context, "Compressed record for type %d", type);
HEXDUMP(garmin->base.context, DC_LOGLEVEL_DEBUG, "data", data, 40);
parse_ANY_timestamp(garmin, time);
len = traverse_regular(garmin, data, datasize, type, &time);
} else if (record & 0x40) { // Definition record?
len = traverse_definition(garmin, data, datasize, record);
} else { // Normal data record
DEBUG(garmin->base.context, "Regular record for type %d", record);
HEXDUMP(garmin->base.context, DC_LOGLEVEL_DEBUG, "data", data, 40);
len = traverse_regular(garmin, data, datasize, record, &time);
}
if (len <= 0 || len > datasize)