Manipulation of raw binary payloads in WarpScript could be done easily with existing functions, no need to call external programs!
Sometimes, you need to process raw payloads. Extract a bit from an array of bytes. Build a byte array. If you play with Warp 10 MQTT plugin (now available on WarpFleet), you have to manipulate the payload you build on your IoT device.
Here is a useful cheat-sheet for bit and bytes manipulation in WarpScript.
Use LONG, BYTES
Most conversions from and to LONG or BYTES (bytes array) type exists. We will take an 8 bytes CAN frame as example payload. It contains two booleans, an integer, and a float:
Analyze your electrical consumption from your Linky and Warp 10 |
This could be described in a C struct, using bit fields:
struct {
unsigned int right_door_opened: 1;
unsigned int left_door_opened: 1;
char: 0; //padding
int batteryVoltage: 24;
float batteryCurrent;
};
Decode payloads
payload.right_door_opened = 1;
payload.left_door_opened = 0;
payload.batteryVoltage = 351;
payload.batteryCurrent = -140.424;
The encoded frame could be represented as a long with value -4392016192336732415
, or c30c6c8b00015f01
in hexadecimal. In WarpScript, you could decode everything in a few lines:
Extract a byte array from a byte array | SUBSTRING |
Read a byte from a byte array, returns a long | GET |
Convert a byte array to a long | TOLONG |
Convert a byte array to a float | TOLONG FLOATBITS-> |
Convert a byte array to a double | TOLONG DOUBLEBITS-> |
Convert a byte array to a string | "UTF-8" BYTES-> |
Read a bit from a byte array, returns a boolean | BYTESTOBITS 56 BITGET |
Reverse a byte array endianness | REVERSE |
Of course, if you define the same C struct on another CPU, you might have to reverse endianness somewhere!
Encode payloads
Here is the code to build the byte array with the same content as the previous example:
Again, convert what you need to long, then to byte arrays, and use +
to concatenate byte arrays. For booleans, use bitwise shift <<
and binary mask |
and &
to build long.
Convert a long to a byte array, from 1 to 8 bytes | 3 ->LONGBYTES |
Concatenate byte arrays together | + |
Convert a float to a byte array | ->FLOATBITS 4 ->LONGBYTES |
Convert a double to a byte array | ->DOUBLEBITS 8 ->LONGBYTES |
Reverse a byte array endianness | REVERSE |
Debug
WarpScript also includes functions to represent byte array as strings. These functions are useful for debugging, checking endianness problems, and so on.
Display byte array in hexadecimal | ->HEX |
Display byte array in binary | ->BIN |
Display byte array in base64 | ->B64 |
Decode a byte array | 'UTF-8' BYTES-> |
Conclusion
Like many languages, WarpScript allows to build or decode any kind of binary payload. If you want to check all available type conversions, read this tutorial!
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