The NetMD query DSL: build command payloads and parse replies from printf/scanf-like format strings, as used by netmd-js and libnetmd.
Format strings mix literal hex bytes with % fields:
| Field | Meaning |
|---|---|
%b | 1-byte integer |
%w | 2-byte integer |
%d | 4-byte integer |
%q | 8-byte integer |
%x | binary preceded by 2 bytes of length |
%s | null-terminated binary preceded by 2 bytes of length |
%z | binary preceded by 1 byte of length |
%* | raw binary (rest of input when scanning) |
%# | rest of input as binary (scan only) |
%? | ignore one byte (scan only) |
%B | BCD-encoded 1-byte number |
%W | BCD-encoded 2-byte number |
Integers are big-endian by default; %< overrides to little-endian for
the following field (%<d), %> explicitly selects big-endian.
Examples
iex> NetMD.Query.format("1808 %b 00", [2])
<<0x18, 0x08, 0x02, 0x00>>
iex> NetMD.Query.scan(<<0x18, 0x08, 0x02, 0x00>>, "1808 %b 00")
{:ok, [2]}Summary
Functions
Decode a binary-coded decimal binary to an integer.
Build a binary query from format and args.
Encode a non-negative integer as binary-coded decimal in length bytes.
Parse data according to format, returning the field values in order.
Same as scan/2 but raises NetMD.Query.ScanError on mismatch.
Types
Functions
@spec bcd_to_int(binary()) :: non_neg_integer()
Decode a binary-coded decimal binary to an integer.
iex> NetMD.Query.bcd_to_int(<<0x99, 0x99>>)
9999Build a binary query from format and args.
Raises ArgumentError on malformed formats or mismatched arguments.
@spec int_to_bcd(non_neg_integer(), pos_integer()) :: binary()
Encode a non-negative integer as binary-coded decimal in length bytes.
iex> NetMD.Query.int_to_bcd(24, 1)
<<0x24>>
iex> NetMD.Query.int_to_bcd(9999, 2)
<<0x99, 0x99>>Parse data according to format, returning the field values in order.
Literal bytes in the format must match the input exactly and the input must be fully consumed.
Same as scan/2 but raises NetMD.Query.ScanError on mismatch.