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Add a HexStringField parser. #12

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Add a HexStringField parser. #12

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12 changes: 11 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,8 @@ need, to make the parsing and printing code smaller and faster.

Some values are parsed to an Arduino `String` value or C++ integer type,
those should be fairly straightforward. There are three special types
that need some explanation: `FixedValue` and `TimestampedFixedValue`.
that need some explanation: `FixedValue`, `TimestampedFixedValue` and
`HexStringField`.

When looking at the DSMR P1 format, it defines a floating point format.
It is described as `Fn(x,y)`, where `n` is the total number of (decimal)
Expand Down Expand Up @@ -201,6 +202,15 @@ Parsing these into something like a UNIX timestamp is tricky (think
leap years and seconds) and of limited use, so this just keeps the
original format.

The final one `HexStringField` is a smart version of the StringField
parser and is only used for equipment id's as in practise these are
often hex coded strings instead of a normal strings. If the given
string is indeed a hex coding, the decoded string is returned else
the original string is returned.

0-0:96.1.1(4530303639303030373138323035333231)
E0069000718205321

## Connecting the P1 port

The P1 port essentially consists of three parts:
Expand Down
47 changes: 41 additions & 6 deletions src/dsmr/fields.h
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Expand Up @@ -73,6 +73,41 @@ namespace dsmr
}
};

// A hexstring field is essencially a string filled with hex digits. If the
// string does not consist of an even number of hex digits, the original
// string is returned, otherwise the decoded hex string is returned.
template <typename T, size_t minlen, size_t maxlen>
struct HexStringField : ParsedField<T>
{
ParseResult<void> parse(const char *str, const char *end)
{
ParseResult<String> res = StringParser::parse_string(minlen, maxlen, str, end);
if (!res.err) {
static_cast<T *>(this)->val() = res.result;

if (res.result.length() & 1) {
// Odd number of chars, can't be a hex coded string.
return res;
}
if (!std::all_of(res.result.begin(), res.result.end(), [](const char ch){ return isxdigit(ch); })) {
// Not all chars are hex digits.
return res;
}
String hexStr;
hexStr.reserve(res.result.length()/2);
for (auto it = res.result.begin(); it != res.result.end(); ++it) {
const unsigned char ch1 = static_cast<unsigned const char>(*it++);
const unsigned char ch2 = static_cast<unsigned const char>(*it);
uint8_t val = (isdigit(ch1) ? ch1 - '0' : toupper(ch1) - 'A' + 10) * 16 +
(isdigit(ch2) ? ch2 - '0' : toupper(ch2) - 'A' + 10);
hexStr.concat(static_cast<char>(val));
}
static_cast<T *>(this)->val() = hexStr;
}
return res;
}
};

// A timestamp is essentially a string using YYMMDDhhmmssX format (where
// X is W or S for wintertime or summertime). Parsing this into a proper
// (UNIX) timestamp is hard to do generically. Parsing it into a
Expand Down Expand Up @@ -275,7 +310,7 @@ namespace dsmr
DEFINE_FIELD(timestamp, String, ObisId(0, 0, 1, 0, 0), TimestampField);

/* Equipment identifier */
DEFINE_FIELD(equipment_id, String, ObisId(0, 0, 96, 1, 1), StringField, 0, 96);
DEFINE_FIELD(equipment_id, String, ObisId(0, 0, 96, 1, 1), HexStringField, 0, 96);

/* Meter Reading electricity delivered to client (Special for Lux) in 0,001 kWh */
/* TODO: by OBIS 1-0:1.8.0.255 IEC 62056 it should be Positive active energy (A+) total [kWh], should we rename it? */
Expand Down Expand Up @@ -495,9 +530,9 @@ namespace dsmr
DEFINE_FIELD(gas_device_type, uint16_t, ObisId(0, GAS_MBUS_ID, 24, 1, 0), IntField, units::none);

/* Equipment identifier (Gas) */
DEFINE_FIELD(gas_equipment_id, String, ObisId(0, GAS_MBUS_ID, 96, 1, 0), StringField, 0, 96);
DEFINE_FIELD(gas_equipment_id, String, ObisId(0, GAS_MBUS_ID, 96, 1, 0), HexStringField, 0, 96);
/* Equipment identifier (Gas) BE */
DEFINE_FIELD(gas_equipment_id_be, String, ObisId(0, GAS_MBUS_ID, 96, 1, 1), StringField, 0, 96);
DEFINE_FIELD(gas_equipment_id_be, String, ObisId(0, GAS_MBUS_ID, 96, 1, 1), HexStringField, 0, 96);

/* Valve position Gas (on/off/released) (Note: Removed in 4.0.7 / 4.2.2 / 5.0). */
DEFINE_FIELD(gas_valve_position, uint8_t, ObisId(0, GAS_MBUS_ID, 24, 4, 0), IntField, units::none);
Expand All @@ -516,7 +551,7 @@ namespace dsmr
DEFINE_FIELD(thermal_device_type, uint16_t, ObisId(0, THERMAL_MBUS_ID, 24, 1, 0), IntField, units::none);

/* Equipment identifier (Thermal: heat or cold) */
DEFINE_FIELD(thermal_equipment_id, String, ObisId(0, THERMAL_MBUS_ID, 96, 1, 0), StringField, 0, 96);
DEFINE_FIELD(thermal_equipment_id, String, ObisId(0, THERMAL_MBUS_ID, 96, 1, 0), HexStringField, 0, 96);

/* Valve position (on/off/released) (Note: Removed in 4.0.7 / 4.2.2 / 5.0). */
DEFINE_FIELD(thermal_valve_position, uint8_t, ObisId(0, THERMAL_MBUS_ID, 24, 4, 0), IntField, units::none);
Expand All @@ -530,7 +565,7 @@ namespace dsmr
DEFINE_FIELD(water_device_type, uint16_t, ObisId(0, WATER_MBUS_ID, 24, 1, 0), IntField, units::none);

/* Equipment identifier (Thermal: heat or cold) */
DEFINE_FIELD(water_equipment_id, String, ObisId(0, WATER_MBUS_ID, 96, 1, 0), StringField, 0, 96);
DEFINE_FIELD(water_equipment_id, String, ObisId(0, WATER_MBUS_ID, 96, 1, 0), HexStringField, 0, 96);

/* Valve position (on/off/released) (Note: Removed in 4.0.7 / 4.2.2 / 5.0). */
DEFINE_FIELD(water_valve_position, uint8_t, ObisId(0, WATER_MBUS_ID, 24, 4, 0), IntField, units::none);
Expand All @@ -544,7 +579,7 @@ namespace dsmr
DEFINE_FIELD(sub_device_type, uint16_t, ObisId(0, SUB_MBUS_ID, 24, 1, 0), IntField, units::none);

/* Equipment identifier (Thermal: heat or cold) */
DEFINE_FIELD(sub_equipment_id, String, ObisId(0, SUB_MBUS_ID, 96, 1, 0), StringField, 0, 96);
DEFINE_FIELD(sub_equipment_id, String, ObisId(0, SUB_MBUS_ID, 96, 1, 0), HexStringField, 0, 96);

/* Valve position (on/off/released) (Note: Removed in 4.0.7 / 4.2.2 / 5.0). */
DEFINE_FIELD(sub_valve_position, uint8_t, ObisId(0, SUB_MBUS_ID, 24, 4, 0), IntField, units::none);
Expand Down