2.3 KiB
For a value v, we write «v» for the binary encoding of v. The
length of an encoding is always available from context: either from
a containing encoded value, or from the overall container of the data,
which could be a file, an HTTP message, a UDP packet, etc.
«#f» = [0xA0]
«#t» = [0xA1]
«F» = [0xA2] ++ binary32(F) if F ∈ Float
«D» = [0xA2] ++ binary64(D) if D ∈ Double
«x» = [0xA3] ++ intbytes(x) if x ∈ SignedInteger
«S» = [0xA4] ++ utf8(S) ++ [0] if S ∈ String
[0xA5] ++ S if S ∈ ByteString
[0xA6] ++ utf8(S) if S ∈ Symbol
«<L F_1...F_m>» = [0xA7] ++ seq(«L», «F_1», ..., «F_m»)
«[X_1...X_m]» = [0xA8] ++ seq(«X_1», ..., «X_m»)
«#{E_1...E_m}» = [0xA9] ++ seq(«E_1», ..., «E_m»)
«{K_1:V_1...K_m:V_m}» = [0xAA] ++ seq(«K_1», «V_1», ..., «K_m», «V_m»)
seq(R_1, ..., R_m) = len(|R_1|) ++ R_1 ++...++ len(|R_m|) ++ R_m
len(m) = e(m, 128)
e(v, d) = [v + d] if v < 128
e(v / 128, 0) ++ [(v % 128) + d] if v ≥ 128
«#!V» = [0xAB] ++ «V»
The functions binary32(F) and binary64(D) yield big-endian 4- and
8-byte IEEE 754 binary representations of F and D, respectively.
The function intbytes(x) is a big-endian two's-complement signed
binary representation of x, taking at least as many whole bytes as
needed to unambiguously identify the value and its sign. intbytes(0)
may be the empty byte sequence.
When reading, the length of the input is supplied externally. This means
that, when reading a length/value pair in a seq(), each length should
be passed down to the decoder for the corresponding value, so that the
decoder knows when to stop.
Annotations. To annotate a Repr r (that MUST NOT itself
already be annotated) with some sequence of Values [v_1, ..., v_m]
(that MUST be non-empty), surround r as follows:
[0xBF] ++ len(|r|) ++ r ++ len(|«v_1»|) ++ «v_1» ++...++ len(|«v_m»|) ++ «v_m»