- bits(+Shift, +Width, ?Word, ?Bits, ?Rest) is semidet
- bits(+ShiftWidthPair, ?Word, ?Bits, ?Rest) is semidet
- bits(+ShiftWidthPair, ?Word, ?Bits) is semidet
- Unifies Bits within a Word using Shift and Width. All arguments are
integers treated as words of arbitrary bit-width.
The implementation uses relational integer arithmetic, i.e. CLP(FD).
Hence allows for forward and backward transformations from Word to
Bits and vice versa. Integer Word applies a Shift and bit Width mask
to integer Bits. Bits is always a smaller integer. Decomposes the
problem into shifting and masking. Treats these operations
|Width||- of Bits from Word after Shift. Width of zero always
- bit_fields(+Fields:list, +Shift:integer, +Int:integer) is semidet
- bit_fields(+Fields:list, +Shift:integer, +Int0:integer, -Int:integer) is semidet
- Two versions of the predicate unify Value:Width bit fields with
integers. The arity-3 version requires a bound Int from which to
find unbound (or bound) values in the Fields; used to extract values
from integers else check values semi-deterministically. The arity-4
version of the predicate accumulates bit-field values by OR-wise
merging shifted bits from Int0 to Int.
The predicates are semi-deterministic. They can fail. Failure occurs
when the bit-field Width integers do not sum to Shift.
|Fields||- is a list of value and width terms of the form
Value:Width where Width is an integer; Value is either a
variable or an integer.
|Shift||- is an integer number of total bits, e.g. 8 for eight-bit
bytes, 16 for sixteen-bit words and so on.|
The following predicates are exported, but not or incorrectly documented.
- bits(Arg1, Arg2, Arg3, Arg4)
- bits(Arg1, Arg2, Arg3)
- bit_fields(Arg1, Arg2, Arg3, Arg4)