preserves/_includes/cheatsheet-binary.md

31 lines
1.5 KiB
Markdown
Raw Normal View History

2023-03-15 16:15:26 +00:00
For a value `V`, we write `«V»` for the binary encoding of `V`.
2023-03-15 15:24:02 +00:00
«#f» = [0x80]
«#t» = [0x81]
«@W V» = [0x85] ++ «W» ++ «V»
2023-03-15 15:24:02 +00:00
«#!V» = [0x86] ++ «V»
2023-10-13 12:21:40 +00:00
«V» if V ∈ Float = [0x87, 0x04] ++ binary32(V)
«V» if V ∈ Double = [0x87, 0x08] ++ binary64(V)
2023-03-15 15:24:02 +00:00
2023-03-15 16:15:26 +00:00
«V» if V ∈ SignedInteger = [0xB0] ++ varint(|intbytes(V)|) ++ intbytes(V)
2023-03-15 15:24:02 +00:00
«V» if V ∈ String = [0xB1] ++ varint(|utf8(V)|) ++ utf8(V)
«V» if V ∈ ByteString = [0xB2] ++ varint(|V|) ++ V
«V» if V ∈ Symbol = [0xB3] ++ varint(|utf8(V)|) ++ utf8(V)
«<L F_1...F_m>» = [0xB4] ++ «L» ++ «F_1» ++...++ «F_m» ++ [0x84]
«[X_1...X_m]» = [0xB5] ++ «X_1» ++...++ «X_m» ++ [0x84]
«#{E_1...E_m}» = [0xB6] ++ «E_1» ++...++ «E_m» ++ [0x84]
«{K_1:V_1...K_m:V_m}» = [0xB7] ++ «K_1» ++ «V_1» ++...++ «K_m» ++ «V_m» ++ [0x84]
varint(v) = [v] if v < 128
[(v & 0x7F) + 128] ++ varint(v >> 7) if v ≥ 128
2023-03-15 15:24:02 +00:00
2023-03-15 16:15:26 +00:00
The functions `binary32(F)` and `binary64(D)` yield big-endian 4- and
8-byte IEEE 754 binary representations of `F` and `D`, respectively.
2023-03-15 15:24:02 +00:00
2023-03-15 16:15:26 +00:00
The function `intbytes(x)` is a big-endian two's-complement signed binary representation of
`x`, taking exactly as many whole bytes as needed to unambiguously identify the value and its
2023-10-13 12:21:40 +00:00
sign. In particular, `intbytes(0)` is the empty byte sequence.