Files
mercury/library/uint16.m
Julien Fischer a194e47c33 Add clamp/3 for other primitive integer types.
library/int.m:
library/int{8,16,64}.m:
library/uint.m:
library/uint(8,16,32,64}.m:
    Add the new function.

NEWS.md:
    Announce the additions.

tests/hard_coded/Mmakefile:
tests/hard_coded/clamp_int*.{m,exp}:
tests/hard_coded/clamp_uint*.{m,exp}:
    Add tests for the new functions.

tests/hard_coded/string_code_point.m:
    Avoid an ambiguity due to this module defining its own version of clamp/3.
    XXX we should replace the local one with a call to int.clamp/3, but this
    module constructs ranges where Max < Min and aborts with the new one.
2026-03-05 16:54:47 +11:00

1149 lines
30 KiB
Mathematica

%---------------------------------------------------------------------------%
% vim: ts=4 sw=4 et ft=mercury
%---------------------------------------------------------------------------%
% Copyright (C) 2017-2023, 2025-2026 The Mercury team.
% This file is distributed under the terms specified in COPYING.LIB.
%---------------------------------------------------------------------------%
%
% File: uint16.m
% Main author: juliensf
% Stability: high.
%
% Predicates and functions for dealing with unsigned 16-bit integer numbers.
%
%---------------------------------------------------------------------------%
:- module uint16.
:- interface.
:- import_module pretty_printer.
%---------------------------------------------------------------------------%
%
% Conversion from int.
%
% from_int(I, U16):
%
% Convert an int into a uint16.
% Fail if I is not in the range [0, 2^16 - 1].
%
:- pred from_int(int::in, uint16::out) is semidet.
% det_from_int(I) = U16:
%
% Convert an int into a uint16.
% Throw an exception if I is not in the range [0, 2^16 - 1].
%
:- func det_from_int(int) = uint16.
% cast_from_int(I) = U16:
%
% Convert an int to a uint16.
% Always succeeds, but will yield a result that is mathematically equal
% to I only if I is in the range [0, 2^16 - 1].
%
:- func cast_from_int(int) = uint16.
%---------------------------------------------------------------------------%
%
% Conversion from uint.
%
% from_uint(U, U16):
%
% Convert a uint into a uint16.
% Fail if U is not in the range [0, 2^16 - 1].
%
:- pred from_uint(uint::in, uint16::out) is semidet.
% det_from_uint(U) = U16:
%
% Convert a uint into a uint16.
% Throw an exception if U is not in the range [0, 2^16 - 1].
%
:- func det_from_uint(uint) = uint16.
% cast_from_uint(U) = U16:
%
% Convert a uint to a uint16.
% Always succeeds, but will yield a result that is mathematically equal
% to U only if U is in the range [0, 2^16 - 1].
%
:- func cast_from_uint(uint) = uint16.
%---------------------------------------------------------------------------%
%
% Conversion to int.
%
% to_int(U16) = I:
%
% Convert a uint16 to an int.
% Always succeeds, and yields a result that is mathematically equal
% to U16.
%
:- func to_int(uint16) = int.
% cast_to_int(U16) = I:
%
% Convert a uint16 to an int.
% Always succeeds, and yields a result that is mathematically equal
% to U16.
%
:- func cast_to_int(uint16) = int.
%---------------------------------------------------------------------------%
%
% Conversion to uint.
%
% cast_to_uint(U16) = U:
%
% Convert a uint16 to a uint.
% Always succeeds, and yields a result that is mathematically equal
% to U16.
%
:- func cast_to_uint(uint16) = uint.
%---------------------------------------------------------------------------%
%
% Conversion to/from uint8
%
% cast_to_uint8(U16) = U8:
%
% Convert a uint16 to a uint8.
% Always succeeds, but will yield a result that is mathematically equal
% to U16 only if U16 is in the range [0, 2^8 - 1].
%
:- func cast_to_uint8(uint16) = uint8.
% cast_from_uint8(U8) = U16:
%
% Convert a uint8 to a uint16.
% Always succeeds, and yields a result that is mathematically equal
% to U8.
%
:- func cast_from_uint8(uint8) = uint16.
%---------------------------------------------------------------------------%
%
% Conversion to/from uint64.
%
% cast_to_uint64(U16) = U64:
%
% Convert a uint16 to a uint64.
% Always succeeds, and yields a result that is mathematically equal
% to U16.
%
:- func cast_to_uint64(uint16) = uint64.
% cast_from_uint64(U64) = U16:
%
% Convert a uint64 to a uint16.
% Always succeeds, but will yield a result that is mathematically equal
% to U64 only if U64 is in the range [0, 2^16 - 1].
%
:- func cast_from_uint64(uint64) = uint16.
%---------------------------------------------------------------------------%
%
% Change of signedness.
%
% cast_from_int16(I16) = U16:
%
% Convert an int16 to a uint16. This will yield a result that is
% mathematically equal to I16 only if I16 is in the range [0, 2^15 - 1].
%
:- func cast_from_int16(int16) = uint16.
%---------------------------------------------------------------------------%
%
% Conversion from byte sequence.
%
% from_bytes_le(LSB, MSB) = U16:
%
% U16 is the uint16 whose least and most significant bytes are given by the
% uint8s LSB and MSB respectively.
%
:- func from_bytes_le(uint8, uint8) = uint16.
% from_bytes_be(MSB, LSB) = U16:
%
% U16 is the uint16 whose least and most significant bytes are given by the
% uint8s LSB and MSB respectively.
%
:- func from_bytes_be(uint8, uint8) = uint16.
%---------------------------------------------------------------------------%
%
% Comparisons and related operations.
%
% Less than.
%
:- pred (uint16::in) < (uint16::in) is semidet.
% Greater than.
%
:- pred (uint16::in) > (uint16::in) is semidet.
% Less than or equal.
%
:- pred (uint16::in) =< (uint16::in) is semidet.
% Greater than or equal.
%
:- pred (uint16::in) >= (uint16::in) is semidet.
% Maximum.
%
:- func max(uint16, uint16) = uint16.
% Minimum.
%
:- func min(uint16, uint16) = uint16.
% clamp(Min, Max, N):
%
% Clamp N to the range [Min, Max] (inclusive).
% Returns Min if N < Min, Max if N > Max, and N otherwise.
% Throws an exception if Max < Min.
%
:- func clamp(uint16, uint16, uint16) = uint16.
%---------------------------------------------------------------------------%
%
% Arithmetic operations.
%
% Addition.
%
:- func uint16 + uint16 = uint16.
:- mode in + in = uo is det.
:- mode uo + in = in is det.
:- mode in + uo = in is det.
:- func plus(uint16, uint16) = uint16.
% Subtraction.
%
:- func uint16 - uint16 = uint16.
:- mode in - in = uo is det.
:- mode uo - in = in is det.
:- mode in - uo = in is det.
:- func minus(uint16, uint16) = uint16.
% Multiplication.
%
:- func (uint16::in) * (uint16::in) = (uint16::uo) is det.
:- func times(uint16, uint16) = uint16.
% Truncating integer division.
%
% Throws a `domain_error' exception if the right operand is zero.
%
:- func (uint16::in) div (uint16::in) = (uint16::uo) is det.
% Truncating integer division.
%
% Throws a `domain_error' exception if the right operand is zero.
%
:- func (uint16::in) // (uint16::in) = (uint16::uo) is det.
% (/)/2 is a synonym for (//)/2.
%
:- func (uint16::in) / (uint16::in) = (uint16::uo) is det.
% unchecked_quotient(X, Y) is the same as X // Y, but the behaviour
% is undefined if the right operand is zero.
%
:- func unchecked_quotient(uint16::in, uint16::in) = (uint16::uo) is det.
% Modulus.
% X mod Y = X - (X div Y) * Y
%
% Throws a `domain_error' exception if the right operand is zero.
%
:- func (uint16::in) mod (uint16::in) = (uint16::uo) is det.
% Remainder.
% X rem Y = X - (X // Y) * Y.
%
% Throws a `domain_error' exception if the right operand is zero.
%
:- func (uint16::in) rem (uint16::in) = (uint16::uo) is det.
% unchecked_rem(X, Y) is the same as X rem Y, but the behaviour is
% undefined if the right operand is zero.
%
:- func unchecked_rem(uint16::in, uint16::in) = (uint16::uo) is det.
% even(X) is equivalent to (X mod 2 = 0).
%
:- pred even(uint16::in) is semidet.
% odd(X) is equivalent to (not even(X)), i.e. (X mod 2 = 1).
%
:- pred odd(uint16::in) is semidet.
%---------------------------------------------------------------------------%
%
% Shift operations.
%
% Left shift.
% X << Y returns X "left shifted" by Y bits.
% The bit positions vacated by the shift are filled by zeros.
% Throws an exception if Y is not in the range [0, 16).
%
:- func (uint16::in) << (int::in) = (uint16::uo) is det.
:- func (uint16::in) <<u (uint::in) = (uint16::uo) is det.
% unchecked_left_shift(X, Y) is the same as X << Y except that the
% behaviour is undefined if Y is not in the range [0, 16).
% It will typically be implemented more efficiently than X << Y.
%
:- func unchecked_left_shift(uint16::in, int::in) = (uint16::uo) is det.
:- func unchecked_left_ushift(uint16::in, uint::in) = (uint16::uo) is det.
% Right shift.
% X >> Y returns X "right shifted" by Y bits.
% The bit positions vacated by the shift are filled by zeros.
% Throws an exception if Y is not in the range [0, 16).
%
:- func (uint16::in) >> (int::in) = (uint16::uo) is det.
:- func (uint16::in) >>u (uint::in) = (uint16::uo) is det.
% unchecked_right_shift(X, Y) is the same as X >> Y except that the
% behaviour is undefined if Y is not in the range [0, 16).
% It will typically be implemented more efficiently than X >> Y.
%
:- func unchecked_right_shift(uint16::in, int::in) = (uint16::uo) is det.
:- func unchecked_right_ushift(uint16::in, uint::in) = (uint16::uo) is det.
%---------------------------------------------------------------------------%
%
% Logical operations.
%
% Bitwise and.
%
:- func (uint16::in) /\ (uint16::in) = (uint16::uo) is det.
% Bitwise or.
%
:- func (uint16::in) \/ (uint16::in) = (uint16::uo) is det.
% Bitwise exclusive or (xor).
%
:- func xor(uint16, uint16) = uint16.
:- mode xor(in, in) = uo is det.
:- mode xor(in, uo) = in is det.
:- mode xor(uo, in) = in is det.
% Bitwise complement.
%
:- func \ (uint16::in) = (uint16::uo) is det.
%---------------------------------------------------------------------------%
%
% Operations on bits and bytes.
%
% num_zeros(U) = N:
%
% N is the number of zeros in the binary representation of U.
%
:- func num_zeros(uint16) = int.
% num_ones(U) = N:
%
% N is the number of ones in the binary representation of U.
%
:- func num_ones(uint16) = int.
% num_leading_zeros(U) = N:
%
% N is the number of leading zeros in the binary representation of U,
% starting at the most significant bit position.
% Note that num_leading_zeros(0u16) = 16.
%
:- func num_leading_zeros(uint16) = int.
% num_trailing_zeros(U) = N:
%
% N is the number of trailing zeros in the binary representation of U,
% starting at the least significant bit position.
% Note that num_trailing_zeros(0u16) = 16.
%
:- func num_trailing_zeros(uint16) = int.
% reverse_bytes(A) = B:
%
% B is the value that results from reversing the bytes in the binary
% representation of A.
%
:- func reverse_bytes(uint16) = uint16.
% reverse_bits(A) = B:
%
% B is the value that results from reversing the bits in the binary
% representation of A.
%
:- func reverse_bits(uint16) = uint16.
% rotate_left(U, D) = N:
%
% N is the value obtained by rotating the binary representation of U
% left by D bits. Throws an exception if D is not in the range [0, 15].
%
:- func rotate_left(uint16, uint) = uint16.
% unchecked_rotate_left(U, D) = N:
%
% N is the value obtained by rotating the binary representation of U
% left by an amount given by the lowest 4 bits of D.
%
:- func unchecked_rotate_left(uint16, uint) = uint16.
% rotate_right(U, D) = N:
%
% N is the value obtained by rotating the binary representation of U
% right by D bits. Throws an exception if D is not in the range [0, 15].
%
:- func rotate_right(uint16, uint) = uint16.
% unchecked_rotate_right(U, D) = N:
%
% N is the value obtained by rotating the binary representation of U
% right by an amount given by the lowest 4 bits of D.
%
:- func unchecked_rotate_right(uint16, uint) = uint16.
% set_bit(U, I) = N:
% N is the value obtained by setting the I'th bit (the bit worth 2^I) of U
% to one. An exception is thrown if I is not in the range [0, 15].
%
:- func set_bit(uint16, uint) = uint16.
% unchecked_set_bit(U, I) = N:
% As above, but the behaviour is undefined if I is not in the range
% [0, 15].
%
:- func unchecked_set_bit(uint16, uint) = uint16.
% clear_bit(U, I) = N:
% N is the value obtained by setting the I'th bit (the bit worth 2^I) of U
% to zero. An exception is thrown if I is not in the range [0, 15].
%
:- func clear_bit(uint16, uint) = uint16.
% unchecked_clear_bit(U, I) = N:
% As above, but the behaviour is undefined if I is not in the range
% [0, 15].
%
:- func unchecked_clear_bit(uint16, uint) = uint16.
% flip_bit(U, I) = N:
% N is the value obtained by flipping the I'th bit (the bit worth 2^I) of
% U. An exception is thrown if I is not in the range [0, 15].
%
:- func flip_bit(uint16, uint) = uint16.
% unchecked_flip_bit(U, I) = N:
% As above, but the behaviour is undefined if I is not in the range
% [0, 15].
%
:- func unchecked_flip_bit(uint16, uint) = uint16.
% bit_is_set(U, I):
% True if-and-only-if the I'th bit (the bit worth 2^I) of U is one.
% An exception is thrown if I is not in the range [0, 15].
%
:- pred bit_is_set(uint16::in, uint::in) is semidet.
% unchecked_bit_is_set(U, I):
% As above, but the behaviour is undefined if I is not in the range
% [0, 15].
%
:- pred unchecked_bit_is_set(uint16::in, uint::in) is semidet.
% bit_is_clear(U, I):
% True if-and-only-if the I'th bit (the bit worth 2^I) of U is zero.
% An exception is thrown if I is not in the range [0, 15].
%
:- pred bit_is_clear(uint16::in, uint::in) is semidet.
% unchecked_bit_is_clear(U, I):
% As above, but the behaviour is undefined if I is not in the range
% [0, 15].
%
:- pred unchecked_bit_is_clear(uint16::in, uint::in) is semidet.
%---------------------------------------------------------------------------%
%
% Limits.
%
:- func max_uint16 = uint16.
%---------------------------------------------------------------------------%
%
% Prettyprinting.
%
% Convert a uint16 to a pretty_printer.doc for formatting.
%
:- func uint16_to_doc(uint16) = pretty_printer.doc.
:- pragma obsolete(func(uint16_to_doc/1), [pretty_printer.uint16_to_doc/1]).
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module exception.
:- import_module int.
:- import_module require.
:- import_module uint.
%---------------------------------------------------------------------------%
from_int(I, U8) :-
I >= 0,
I =< 65_535,
U8 = cast_from_int(I).
det_from_int(I) = U16 :-
( if from_int(I, U16Prime) then
U16 = U16Prime
else
error($pred, "cannot convert int to uint16")
).
:- pragma foreign_proc("C",
cast_from_int(I::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U16 = (uint16_t) I;
").
:- pragma foreign_proc("C#",
cast_from_int(I::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) I;
").
:- pragma foreign_proc("Java",
cast_from_int(I::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (short) I;
").
%---------------------------------------------------------------------------%
from_uint(U, U16) :-
U =< 65_535u,
U16 = cast_from_uint(U).
det_from_uint(U) = U16 :-
( if from_uint(U, U16Prime) then
U16 = U16Prime
else
error($pred, "cannot convert uint to uint16")
).
:- pragma foreign_proc("C",
cast_from_uint(U::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U16 = (uint16_t) U;
").
:- pragma foreign_proc("C#",
cast_from_uint(U::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) U;
").
:- pragma foreign_proc("Java",
cast_from_uint(U::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (short) U;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
I = U16;
").
:- pragma foreign_proc("C#",
to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
I = U16;
").
:- pragma foreign_proc("Java",
to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
I = U16 & 0xffff;
").
:- pragma foreign_proc("C",
cast_to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
I = U16;
").
:- pragma foreign_proc("C#",
cast_to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
I = U16;
").
:- pragma foreign_proc("Java",
cast_to_int(U16::in) = (I::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
I = U16 & 0xffff;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_to_uint(U16::in) = (U::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U = (MR_Unsigned) U16;
").
:- pragma foreign_proc("C#",
cast_to_uint(U16::in) = (U::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U = (uint) U16;
").
:- pragma foreign_proc("Java",
cast_to_uint(U16::in) = (U::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U = U16 & 0xffff;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_to_uint8(U16::in) = (U8::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U8 = (uint8_t) U16;
").
:- pragma foreign_proc("C#",
cast_to_uint8(U16::in) = (U8::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U8 = (byte) U16;
").
:- pragma foreign_proc("Java",
cast_to_uint8(U16::in) = (U8::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U8 = (byte) U16;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_from_uint8(U8::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U16 = (uint16_t) U8;
").
:- pragma foreign_proc("C#",
cast_from_uint8(U8::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) U8;
").
:- pragma foreign_proc("Java",
cast_from_uint8(U8::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (short) (U8 & 0xff);
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_to_uint64(U16::in) = (U64::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U64 = (uint64_t) U16;
").
:- pragma foreign_proc("C#",
cast_to_uint64(U16::in) = (U64::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U64 = (ulong) U16;
").
:- pragma foreign_proc("Java",
cast_to_uint64(U16::in) = (U64::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U64 = (long) U16 & 0xffffL;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_from_uint64(U64::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U16 = (uint16_t) U64;
").
:- pragma foreign_proc("C#",
cast_from_uint64(U64::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) U64;
").
:- pragma foreign_proc("Java",
cast_from_uint64(U64::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (short) U64;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
cast_from_int16(I16::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail,
does_not_affect_liveness],
"
U16 = (uint16_t) I16;
").
:- pragma foreign_proc("C#",
cast_from_int16(I16::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) I16;
").
:- pragma foreign_proc("Java",
cast_from_int16(I16::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = I16;
").
%---------------------------------------------------------------------------%
:- pragma foreign_proc("C",
from_bytes_le(LSB::in, MSB::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail],
"
unsigned char *uint16_bytes = (unsigned char *) &U16;
#if defined(MR_BIG_ENDIAN)
uint16_bytes[0] = MSB;
uint16_bytes[1] = LSB;
#else
uint16_bytes[0] = LSB;
uint16_bytes[1] = MSB;
#endif
").
:- pragma foreign_proc("Java",
from_bytes_le(LSB::in, MSB::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (short) (MSB << java.lang.Byte.SIZE | (LSB & 0x00ff));
").
:- pragma foreign_proc("C#",
from_bytes_le(LSB::in, MSB::in) = (U16::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U16 = (ushort) (MSB << 8 | (LSB & 0x00ff));
").
from_bytes_be(MSB, LSB) =
from_bytes_le(LSB, MSB).
%---------------------------------------------------------------------------%
% The comparison operations <, >, =< and >= are builtins.
max(X, Y) =
( if X > Y then X else Y ).
min(X, Y) =
( if X < Y then X else Y ).
clamp(Min, Max, N) =
( if Max >= Min then
( if N < Min then Min else if N > Max then Max else N )
else
func_error($pred, "Max < Min")
).
%---------------------------------------------------------------------------%
% The operations +, -, plus, minus, *, and times are builtins.
X div Y = X // Y.
:- pragma inline(func('//'/2)).
X // Y = Div :-
( if Y = 0u16 then
throw(domain_error("uint16.'//': division by zero"))
else
Div = unchecked_quotient(X, Y)
).
:- pragma inline(func('/'/2)).
X / Y = X // Y.
X mod Y = X rem Y.
:- pragma inline(func(rem/2)).
X rem Y = Rem :-
( if Y = 0u16 then
throw(domain_error("uint16.rem: division by zero"))
else
Rem = unchecked_rem(X, Y)
).
:- pragma inline(pred(even/1)).
even(X) :-
(X /\ 1u16) = 0u16.
:- pragma inline(pred(odd/1)).
odd(X) :-
(X /\ 1u16) \= 0u16.
%---------------------------------------------------------------------------%
% The unchecked shift operations are builtins.
X << Y = Result :-
( if cast_from_int(Y) < 16u then
Result = unchecked_left_shift(X, Y)
else
Msg = "uint16.(<<): second operand is out of range",
throw(domain_error(Msg))
).
X <<u Y = Result :-
( if Y < 16u then
Result = unchecked_left_ushift(X, Y)
else
Msg = "uint16.(<<u): second operand is out of range",
throw(domain_error(Msg))
).
X >> Y = Result :-
( if cast_from_int(Y) < 16u then
Result = unchecked_right_shift(X, Y)
else
Msg = "uint16.(>>): second operand is out of range",
throw(domain_error(Msg))
).
X >>u Y = Result :-
( if Y < 16u then
Result = unchecked_right_ushift(X, Y)
else
Msg = "uint16.(>>u): second operand is out of range",
throw(domain_error(Msg))
).
%---------------------------------------------------------------------------%
% The algorithms in this section are adapted from chapter 5 of
% ``Hacker's Delight'' by Henry S. Warren, Jr.
num_zeros(U) = 16 - num_ones(U).
:- pragma foreign_proc("C",
num_ones(U::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail],
"
U = (U & 0x5555) + ((U >> 1) & 0x5555);
U = (U & 0x3333) + ((U >> 2) & 0x3333);
U = (U & 0x0f0f) + ((U >> 4) & 0x0f0f);
U = (U & 0x00ff) + ((U >> 8) & 0x00ff);
N = U;
").
:- pragma foreign_proc("C#",
num_ones(U::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
U = (ushort) ((U & 0x5555) + ((U >> 1) & 0x5555));
U = (ushort) ((U & 0x3333) + ((U >> 2) & 0x3333));
U = (ushort) ((U & 0x0f0f) + ((U >> 4) & 0x0f0f));
U = (ushort) ((U & 0x00ff) + ((U >> 8) & 0x00ff));
N = (int) U;
").
:- pragma foreign_proc("Java",
num_ones(U::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N = java.lang.Integer.bitCount(U << 16);
").
%---------------------%
:- pragma foreign_proc("C",
num_leading_zeros(U::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail],
"
if (U == 0) {
N = 16;
} else {
int n = 1;
if ((U >> 8) == 0) { n = n + 8; U = U << 8; }
if ((U >> 12) == 0) { n = n + 4; U = U << 4; }
if ((U >> 14) == 0) { n = n + 2; U = U << 2; }
if ((U >> 15) == 0) { n = n + 1; U = U << 1; }
N = n - (int) (U >> 15);
}
").
:- pragma foreign_proc("C#",
num_leading_zeros(U::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
if (U == 0) {
N = 16;
} else {
int n = 1;
if ((U >> 8) == 0) { n = n + 8; U = (ushort) (U << 8); }
if ((U >> 12) == 0) { n = n + 4; U = (ushort) (U << 4); }
if ((U >> 14) == 0) { n = n + 2; U = (ushort) (U << 2); }
if ((U >> 15) == 0) { n = n + 1; U = (ushort) (U << 1); }
N = n - (int) (U >> 15);
}
").
:- pragma foreign_proc("Java",
num_leading_zeros(I::in) = (N::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
if (I == 0) {
N = 16;
} else {
N = java.lang.Integer.numberOfLeadingZeros(I << 16);
}
").
%---------------------%
num_trailing_zeros(U) =
16 - num_leading_zeros(\ U /\ (U - 1u16)).
%---------------------%
:- pragma foreign_proc("C",
reverse_bytes(A::in) = (B::out),
[will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail],
"
B = MR_uint16_reverse_bytes(A);
").
:- pragma foreign_proc("Java",
reverse_bytes(A::in) = (B::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
B = java.lang.Short.reverseBytes(A);
").
reverse_bytes(A) = B :-
B = (A >> 8) \/ (A << 8).
%---------------------%
:- pragma foreign_proc("Java",
reverse_bits(A::in) = (B::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
B = (short) (java.lang.Integer.reverse(A << 16) & 0xffff);
").
reverse_bits(!.A) = B :-
!:A = (((\ 0x5555u16) /\ !.A) >> 1) \/ ((0x5555u16 /\ !.A) << 1),
!:A = (((\ 0x3333u16) /\ !.A) >> 2) \/ ((0x3333u16 /\ !.A) << 2),
!:A = (((\ 0x0f0fu16) /\ !.A) >> 4) \/ ((0x0f0fu16 /\ !.A) << 4),
!:A = (((\ 0x00ffu16) /\ !.A) >> 8) \/ ((0x00ffu16 /\ !.A) << 8),
B = !.A.
%---------------------------------------------------------------------------%
rotate_left(X, N) =
( if N < 16u then
unchecked_rotate_left(X, N)
else
func_error($pred, "rotate amount exceeds 15 bits")
).
:- pragma foreign_proc("C",
unchecked_rotate_left(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
// XXX clang has intrinsics for rotation -- we should use those instead.
Result = (X << N) | (X >> (-N & 15));
").
:- pragma foreign_proc("C#",
unchecked_rotate_left(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
Result = (ushort) ((X << (int) N) | (X >> (int) (-N & 15)));
").
:- pragma foreign_proc("Java",
unchecked_rotate_left(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
Result = (short) ((X << (int) N) | (X >>> (int) (-N & 15)));
").
%---------------------------------------------------------------------------%
rotate_right(X, N) =
( if N < 16u then
unchecked_rotate_right(X, N)
else
func_error($pred, "rotate amount exceeds 15 bits")
).
:- pragma foreign_proc("C",
unchecked_rotate_right(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
Result = (X >> N) | (X << (-N & 15));
").
:- pragma foreign_proc("C#",
unchecked_rotate_right(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
Result = (ushort) ((X >> (int) N) | (X << (int) (-N & 15)));
").
:- pragma foreign_proc("Java",
unchecked_rotate_right(X::in, N::in) = (Result::out),
[will_not_call_mercury, promise_pure, thread_safe],
"
N &= 15;
Result = (short) ((X >>> (int) N) | (X << (int) (-N & 15)));
").
%---------------------------------------------------------------------------%
set_bit(U, I) =
( if I < 16u then
unchecked_set_bit(U, I)
else
func_error($pred, "bit index exceeds 15 bits")
).
unchecked_set_bit(U, I) =
U \/ (1u16 `unchecked_left_shift` cast_to_int(I)).
clear_bit(U, I) =
( if I < 16u then
unchecked_clear_bit(U, I)
else
func_error($pred, "bit index exceeds 15 bits")
).
unchecked_clear_bit(U, I) =
U /\ (\ (1u16 `unchecked_left_shift` cast_to_int(I))).
flip_bit(U, I) =
( if I < 16u then
unchecked_flip_bit(U, I)
else
func_error($pred, "bit index exceeds 15 bits")
).
unchecked_flip_bit(U, I) =
U `xor` (1u16 `unchecked_left_shift` cast_to_int(I)).
bit_is_set(U, I) :-
( if I < 16u then
unchecked_bit_is_set(U, I)
else
error($pred, "bit index exceeds 15 bits")
).
unchecked_bit_is_set(U, I) :-
U /\ (1u16 `unchecked_left_shift` cast_to_int(I)) \= 0u16.
bit_is_clear(U, I) :-
( if I < 16u then
unchecked_bit_is_clear(U, I)
else
error($pred, "bit index exceeds 15 bits")
).
unchecked_bit_is_clear(U, I) :-
U /\ (1u16 `unchecked_left_shift` cast_to_int(I)) = 0u16.
%---------------------------------------------------------------------------%
max_uint16 = 65_535_u16.
%---------------------------------------------------------------------------%
uint16_to_doc(U) = pretty_printer.uint16_to_doc(U).
%---------------------------------------------------------------------------%
:- end_module uint16.
%---------------------------------------------------------------------------%