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Move the unit conversion to the last moment

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Processing the data in device units, and performing the unit conversion
only at the very last moment, avoids the need for intermediate floating
point math and thus possible rounding errors. In practice this is not
really an important issue, except for some case where a negative zero
value was returned.
This commit is contained in:
Jef Driesen 2021-06-18 20:36:31 +02:00
parent 6645b3f5e4
commit da2446283a
1 changed files with 15 additions and 15 deletions
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30
src/uwatec_smart_parser.c
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@ -940,9 +940,9 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
unsigned int rbt = 99; unsigned int rbt = 99;
unsigned int tank = 0; unsigned int tank = 0;
unsigned int gasmix = 0; unsigned int gasmix = 0;
double depth = 0, depth_calibration = 0; unsigned int depth = 0, depth_calibration = 0;
double temperature = 0; int temperature = 0;
double pressure = 0; unsigned int pressure = 0;
unsigned int heartrate = 0; unsigned int heartrate = 0;
unsigned int bearing = 0; unsigned int bearing = 0;
unsigned int bookmark = 0; unsigned int bookmark = 0;
@ -1026,8 +1026,8 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
const uwatec_smart_event_info_t *events = NULL; const uwatec_smart_event_info_t *events = NULL;
switch (table[id].type) { switch (table[id].type) {
case PRESSURE_DEPTH: case PRESSURE_DEPTH:
pressure += ((signed char) ((svalue >> NBITS) & 0xFF)) / 4.0; pressure += (signed char) ((svalue >> NBITS) & 0xFF);
depth += ((signed char) (svalue & 0xFF)) / 50.0; depth += (signed char) (svalue & 0xFF);
complete = 1; complete = 1;
break; break;
case RBT: case RBT:
@ -1040,37 +1040,37 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
break; break;
case TEMPERATURE: case TEMPERATURE:
if (table[id].absolute) { if (table[id].absolute) {
temperature = svalue / 2.5; temperature = svalue;
have_temperature = 1; have_temperature = 1;
} else { } else {
temperature += svalue / 2.5; temperature += svalue;
} }
break; break;
case PRESSURE: case PRESSURE:
if (table[id].absolute) { if (table[id].absolute) {
if (parser->trimix) { if (parser->trimix) {
tank = (value & 0xF000) >> 12; tank = (value & 0xF000) >> 12;
pressure = (value & 0x0FFF) / 4.0; pressure = (value & 0x0FFF);
} else { } else {
tank = table[id].index; tank = table[id].index;
pressure = value / 4.0; pressure = value;
} }
have_pressure = 1; have_pressure = 1;
gasmix = tank; gasmix = tank;
} else { } else {
pressure += svalue / 4.0; pressure += svalue;
} }
break; break;
case DEPTH: case DEPTH:
if (table[id].absolute) { if (table[id].absolute) {
depth = value / 50.0; depth = value;
if (!calibrated) { if (!calibrated) {
calibrated = 1; calibrated = 1;
depth_calibration = depth; depth_calibration = depth;
} }
have_depth = 1; have_depth = 1;
} else { } else {
depth += svalue / 50.0; depth += svalue;
} }
complete = 1; complete = 1;
break; break;
@ -1195,7 +1195,7 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
} }
if (have_temperature) { if (have_temperature) {
sample.temperature = temperature; sample.temperature = temperature / 2.5;
if (callback) callback (DC_SAMPLE_TEMPERATURE, sample, userdata); if (callback) callback (DC_SAMPLE_TEMPERATURE, sample, userdata);
} }
@ -1216,7 +1216,7 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
idx = uwatec_smart_find_tank(parser, tank); idx = uwatec_smart_find_tank(parser, tank);
if (idx < parser->ntanks) { if (idx < parser->ntanks) {
sample.pressure.tank = idx; sample.pressure.tank = idx;
sample.pressure.value = pressure; sample.pressure.value = pressure / 4.0;
if (callback) callback (DC_SAMPLE_PRESSURE, sample, userdata); if (callback) callback (DC_SAMPLE_PRESSURE, sample, userdata);
} }
} }
@ -1233,7 +1233,7 @@ uwatec_smart_parse (uwatec_smart_parser_t *parser, dc_sample_callback_t callback
} }
if (have_depth) { if (have_depth) {
sample.depth = (depth - depth_calibration) / salinity; sample.depth = (depth - depth_calibration) / 50.0 / salinity;
if (callback) callback (DC_SAMPLE_DEPTH, sample, userdata); if (callback) callback (DC_SAMPLE_DEPTH, sample, userdata);
} }