Conversion to and from Cstruct.t
of_cstruct_be ~bits cs
interprets the bit pattern of cs
as a t
in big-endian.
If ~bits
is not given, the operation considers the entire cs
, otherwise the initial min ~bits (bit-length cs)
bits of cs
.
Assuming n
is the number of bits to extract, the n
-bit in cs
is always the least significant bit of the result. Therefore:
- if the bit size
k
oft
is larger thann
,k - n
most significant bits in the result are0
; and - if
k
is smaller thann
, the result containsk
last of then
first bits ofcs
.
to_cstruct_be ~size t
is the big-endian representation of t
.
If ~size
is not given, it defaults to the minimal number of bytes needed to represent t
, which is bits t / 8
rounded up.
The least-significant bit of t
is always the last bit in the result. If the size is larger than needed, the output is padded with zero bits. If it is smaller, the high bits in t
are dropped.
into_cstruct_be t cs
writes the big-endian representation of t
into cs
. It behaves like to_cstruct_be
, with ~size
spanning the entire cs
.
Random generation
val gen : ?g:Mirage_crypto_rng.g -> Z.t -> Z.t
gen ~g n
picks a value in the interval [0, n - 1]
uniformly at random.
val gen_r : ?g:Mirage_crypto_rng.g -> Z.t -> Z.t -> Z.t
gen_r ~g low high
picks a value from the interval [low, high - 1]
uniformly at random.