%---------------------------------------------------------------------------% % vim: ts=4 sw=4 et ft=mercury %---------------------------------------------------------------------------% % Copyright (C) 2017-2021 The Mercury team. % This file is distributed under the terms specified in COPYING.LIB. %---------------------------------------------------------------------------% % % File: uint8.m % Main author: juliensf % Stability: low. % % Predicates and functions for dealing with unsigned 8-bit integer numbers. % %---------------------------------------------------------------------------% :- module uint8. :- interface. :- import_module pretty_printer. %---------------------------------------------------------------------------% % % Conversion from int. % % from_int(I, U8): % % Convert an int to a uint8. % Fails if I is not in [0, 2^8 - 1]. % :- pred from_int(int::in, uint8::out) is semidet. % det_from_int(I) = U8: % % Convert an int to a uint8. % Throws an exception if I is not in [0, 2^8 - 1]. % :- func det_from_int(int) = uint8. % cast_from_int(I) = U8: % % Convert an int to a uint8. % Always succeeds, but will yield a result that is mathematically equal % to I only if I is in [0, 2^8 - 1]. % :- func cast_from_int(int) = uint8. %---------------------------------------------------------------------------% % % Conversion from uint. % % from_uint(U, U8): % % Convert a uint to a uint8. % Fails if U is not in [0, 2^8 - 1]. % :- pred from_uint(uint::in, uint8::out) is semidet. % det_from_uint(U) = U8: % % Convert a uint to a uint8. % Throws an exception if U is not in [0, 2^8 - 1]. % :- func det_from_uint(uint) = uint8. % cast_from_uint(U) = U8: % % Convert a uint to a uint8. % Always succeeds, but will yield a result that is mathematically equal % to U only if U is in [0, 2^8 - 1]. % :- func cast_from_uint(uint) = uint8. %---------------------------------------------------------------------------% % % Conversion to int. % % to_int(U8) = I: % % Convert a uint8 to an int. % Always succeeds, and yields a result that is mathematically equal % to U8. % :- func to_int(uint8) = int. % cast_to_int(U8) = I: % % Convert a uint8 to an int. % Always succeeds, and yields a result that is mathematically equal % to U8. % :- func cast_to_int(uint8) = int. %---------------------------------------------------------------------------% % % Conversion to uint. % % cast_to_uint(U8) = U: % % Convert a uint8 to a uint. % Always succeeds, and yields a result that is mathematically equal % to U8. % :- func cast_to_uint(uint8) = uint. %---------------------------------------------------------------------------% % % Change of signedness. % % cast_from_int8(I8) = U8: % % Convert an int8 to a uint8. This will yield a result that is % mathematically equal to I8 only if I8 is in [0, 2^7 - 1]. % :- func cast_from_int8(int8) = uint8. %---------------------------------------------------------------------------% % % Comparisons and related operations. % % Less than. % :- pred (uint8::in) < (uint8::in) is semidet. % Greater than. % :- pred (uint8::in) > (uint8::in) is semidet. % Less than or equal. % :- pred (uint8::in) =< (uint8::in) is semidet. % Greater than or equal. % :- pred (uint8::in) >= (uint8::in) is semidet. % Maximum. % :- func max(uint8, uint8) = uint8. % Minimum. % :- func min(uint8, uint8) = uint8. %---------------------------------------------------------------------------% % % Arithmetic operations. % % Addition. % :- func uint8 + uint8 = uint8. :- mode in + in = uo is det. :- mode uo + in = in is det. :- mode in + uo = in is det. :- func plus(uint8, uint8) = uint8. % Subtraction. % :- func uint8 - uint8 = uint8. :- mode in - in = uo is det. :- mode uo - in = in is det. :- mode in - uo = in is det. :- func minus(uint8, uint8) = uint8. % Multiplication. % :- func (uint8::in) * (uint8::in) = (uint8::uo) is det. :- func times(uint8, uint8) = uint8. % Truncating integer division. % % Throws a `domain_error' exception if the right operand is zero. % :- func (uint8::in) div (uint8::in) = (uint8::uo) is det. % Truncating integer division. % % Throws a `domain_error' exception if the right operand is zero. % :- func (uint8::in) // (uint8::in) = (uint8::uo) is det. % (/)/2 is a synonym for (//)/2. % :- func (uint8::in) / (uint8::in) = (uint8::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(uint8::in, uint8::in) = (uint8::uo) is det. % Modulus. % X mod Y = X - (X div Y) * Y % % Throws a `domain_error' exception if the right operand is zero. % :- func (uint8::in) mod (uint8::in) = (uint8::uo) is det. % Remainder. % X rem Y = X - (X // Y) * Y. % % Throws a `domain_error/` exception if the right operand is zero. % :- func (uint8::in) rem (uint8::in) = (uint8::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(uint8::in, uint8::in) = (uint8::uo) is det. % even(X) is equivalent to (X mod 2u8 = 0u8). % :- pred even(uint8::in) is semidet. % odd(X) is equivalent to (not even(X)), i.e. (X mod 2u8 = 1u8). % :- pred odd(uint8::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 [0, 8). % :- func (uint8::in) << (int::in) = (uint8::uo) is det. :- func (uint8::in) <> 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 [0, 8). % :- func (uint8::in) >> (int::in) = (uint8::uo) is det. :- func (uint8::in) >>u (uint::in) = (uint8::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 [0, 8). % It will typically be implemented more efficiently than X >> Y. % :- func unchecked_right_shift(uint8::in, int::in) = (uint8::uo) is det. :- func unchecked_right_ushift(uint8::in, uint::in) = (uint8::uo) is det. %---------------------------------------------------------------------------% % % Logical operations. % % Bitwise and. % :- func (uint8::in) /\ (uint8::in) = (uint8::uo) is det. % Bitwise or. % :- func (uint8::in) \/ (uint8::in) = (uint8::uo) is det. % Bitwise exclusive or (xor). % :- func xor(uint8, uint8) = uint8. :- mode xor(in, in) = uo is det. :- mode xor(in, uo) = in is det. :- mode xor(uo, in) = in is det. % Bitwise complement. % :- func \ (uint8::in) = (uint8::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(uint8) = int. % num_ones(U) = N: % % N is the number of ones in the binary representation of U. % :- func num_ones(uint8) = 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(0u8) = 8. % :- func num_leading_zeros(uint8) = 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(0u8) = 8. % :- func num_trailing_zeros(uint8) = int. % reverse_bits(A) = B: % % B is the is value that results from reversing the bits in the binary % representation of A. % :- func reverse_bits(uint8) = uint8. % 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, 7]. % :- func rotate_left(uint8, uint) = uint8. % 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 3 bits of D. % :- func unchecked_rotate_left(uint8, uint) = uint8. % 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, 7]. % :- func rotate_right(uint8, uint) = uint8. % unchecked_rotate_left(U, D) = N: % % N is the value obtained by rotating the binary representation of U % right by an amount given by the lowest 3 bits of D. % :- func unchecked_rotate_right(uint8, uint) = uint8. % 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, 7]. % :- func set_bit(uint8, uint) = uint8. % unchecked_set_bit(U, I) = N: % As above, but the behaviour is undefined if I is not in the range % [0, 7]. % :- func unchecked_set_bit(uint8, uint) = uint8. % 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, 7]. % :- func clear_bit(uint8, uint) = uint8. % unchecked_clear_bit(U, I) = N: % As above, but the behaviour is undefined if I is not in the range % [0, 7]. % :- func unchecked_clear_bit(uint8, uint) = uint8. % 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, 7]. % :- func flip_bit(uint8, uint) = uint8. % unchecked_flip_bit(U, I) = N: % As above, but the behaviour is undefined if I is not in the range % [0, 7]. % :- func unchecked_flip_bit(uint8, uint) = uint8. % bit_is_set(U, I): % True iff 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, 7]. % :- pred bit_is_set(uint8::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, 7]. % :- pred unchecked_bit_is_set(uint8::in, uint::in) is semidet. % bit_is_clear(U, I): % True iff 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, 7]. % :- pred bit_is_clear(uint8::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, 7]. % :- pred unchecked_bit_is_clear(uint8::in, uint::in) is semidet. %---------------------------------------------------------------------------% % % Limits. % :- func max_uint8 = uint8. %---------------------------------------------------------------------------% % % Prettyprinting. % % Convert an uint8 to a pretty_printer.doc for formatting. % :- func uint8_to_doc(uint8) = pretty_printer.doc. :- pragma obsolete(func(uint8_to_doc/1), [pretty_printer.uint8_to_doc/1]). %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% :- implementation. :- import_module exception. :- import_module int. :- import_module require. :- import_module uint. %---------------------------------------------------------------------------% from_int(I, U8) :- I >= 0, I =< 255, U8 = cast_from_int(I). det_from_int(I) = U8 :- ( if from_int(I, U8Prime) then U8 = U8Prime else error($pred, "cannot convert int to uint8") ). :- pragma foreign_proc("C", cast_from_int(I::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " U8 = (uint8_t) I; "). :- pragma foreign_proc("C#", cast_from_int(I::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = (byte) I; "). :- pragma foreign_proc("Java", cast_from_int(I::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = (byte) I; "). %---------------------------------------------------------------------------% from_uint(U, U8) :- U =< 255u, U8 = cast_from_uint(U). det_from_uint(U) = U8 :- ( if from_uint(U, U8Prime) then U8 = U8Prime else error($pred, "cannot convert uint to uint8") ). :- pragma foreign_proc("C", cast_from_uint(U::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " U8 = (uint8_t) U; "). :- pragma foreign_proc("C#", cast_from_uint(U::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = (byte) U; "). :- pragma foreign_proc("Java", cast_from_uint(U::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = (byte) U; "). %---------------------------------------------------------------------------% :- pragma foreign_proc("C", to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " I = U8; "). :- pragma foreign_proc("C#", to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe], " I = U8; "). :- pragma foreign_proc("Java", to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe], " I = U8 & 0xff; "). :- pragma foreign_proc("C", cast_to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " I = U8; "). :- pragma foreign_proc("C#", cast_to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe], " I = U8; "). :- pragma foreign_proc("Java", cast_to_int(U8::in) = (I::out), [will_not_call_mercury, promise_pure, thread_safe], " I = U8 & 0xff; "). %---------------------------------------------------------------------------% :- pragma foreign_proc("C", cast_to_uint(U8::in) = (U::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " U = (MR_Unsigned) U8; "). :- pragma foreign_proc("C#", cast_to_uint(U8::in) = (U::out), [will_not_call_mercury, promise_pure, thread_safe], " U = (uint) U8; "). :- pragma foreign_proc("Java", cast_to_uint(U8::in) = (U::out), [will_not_call_mercury, promise_pure, thread_safe], " U = U8 & 0xff; "). %---------------------------------------------------------------------------% :- pragma foreign_proc("C", cast_from_int8(I8::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail, does_not_affect_liveness], " U8 = (uint8_t) I8; "). :- pragma foreign_proc("C#", cast_from_int8(I8::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = (byte) I8; "). :- pragma foreign_proc("Java", cast_from_int8(I8::in) = (U8::out), [will_not_call_mercury, promise_pure, thread_safe], " U8 = I8; "). %---------------------------------------------------------------------------% % 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 ). %---------------------------------------------------------------------------% % The operations +, -, plus, minus, *, and times are builtins. X div Y = X // Y. :- pragma inline(func('//'/2)). X // Y = Div :- ( if Y = 0u8 then throw(domain_error("uint8.'//': 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 = 0u8 then throw(domain_error("uint8.rem: division by zero")) else Rem = unchecked_rem(X, Y) ). :- pragma inline(pred(even/1)). even(X) :- (X /\ 1u8) = 0u8. :- pragma inline(pred(odd/1)). odd(X) :- (X /\ 1u8) \= 0u8. %---------------------------------------------------------------------------% % The unchecked shift operations are builtins. X << Y = Result :- ( if cast_from_int(Y) < 8u then Result = unchecked_left_shift(X, Y) else Msg = "uint8.(<<): second operand is out of range", throw(domain_error(Msg)) ). X <> Y = Result :- ( if cast_from_int(Y) < 8u then Result = unchecked_right_shift(X, Y) else Msg = "uint8.(>>): second operand is out of range", throw(domain_error(Msg)) ). X >>u Y = Result :- ( if Y < 8u then Result = unchecked_right_ushift(X, Y) else Msg = "uint8.(>>u): second operand is out of range", throw(domain_error(Msg)) ). %---------------------------------------------------------------------------% num_zeros(U) = 8 - num_ones(U). :- pragma foreign_decl("C", " extern const uint8_t ML_uint8_num_ones_table[]; "). :- pragma foreign_code("C", " const uint8_t ML_uint8_num_ones_table[256] = { 0,1,1,2,1,2,2,3, 1,2,2,3,2,3,3,4, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 4,5,5,6,5,6,6,7, 5,6,6,7,6,7,7,8 }; "). :- pragma foreign_code("C#", " public static byte[] num_ones_table = { 0,1,1,2,1,2,2,3, 1,2,2,3,2,3,3,4, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 1,2,2,3,2,3,3,4, 2,3,3,4,3,4,4,5, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 2,3,3,4,3,4,4,5, 3,4,4,5,4,5,5,6, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 3,4,4,5,4,5,5,6, 4,5,5,6,5,6,6,7, 4,5,5,6,5,6,6,7, 5,6,6,7,6,7,7,8 }; "). :- pragma foreign_proc("C", num_ones(U::in) = (N::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail], " N = ML_uint8_num_ones_table[U]; "). :- pragma foreign_proc("C#", num_ones(U::in) = (N::out), [will_not_call_mercury, promise_pure, thread_safe], " N = mercury.uint8.num_ones_table[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 << 24); "). %---------------------% :- pragma foreign_decl("C", " extern const uint8_t ML_uint8_nlz_table[]; "). :- pragma foreign_code("C", " const uint8_t ML_uint8_nlz_table[256] = { 8,7,6,6,5,5,5,5, 4,4,4,4,4,4,4,4, 3,3,3,3,3,3,3,3, 3,3,3,3,3,3,3,3, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0 }; "). :- pragma foreign_code("C#", " public static byte[] nlz_table = { 8,7,6,6,5,5,5,5, 4,4,4,4,4,4,4,4, 3,3,3,3,3,3,3,3, 3,3,3,3,3,3,3,3, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0 }; "). :- pragma foreign_code("Java", " public static byte[] nlz_table = { 8,7,6,6,5,5,5,5, 4,4,4,4,4,4,4,4, 3,3,3,3,3,3,3,3, 3,3,3,3,3,3,3,3, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0 }; "). :- pragma foreign_proc("C", num_leading_zeros(I::in) = (N::out), [will_not_call_mercury, promise_pure, thread_safe, will_not_modify_trail], " N = ML_uint8_nlz_table[I]; "). :- pragma foreign_proc("C#", num_leading_zeros(U::in) = (N::out), [will_not_call_mercury, promise_pure, thread_safe], " N = mercury.uint8.nlz_table[U]; "). :- pragma foreign_proc("Java", num_leading_zeros(U::in) = (N::out), [will_not_call_mercury, promise_pure, thread_safe], " N = jmercury.uint8.nlz_table[U & 0xff]; "). num_trailing_zeros(U) = 8 - num_leading_zeros(\ U /\ (U - 1u8)). %---------------------% :- pragma foreign_proc("Java", reverse_bits(A::in) = (B::out), [will_not_call_mercury, promise_pure, thread_safe], " B = (byte) (java.lang.Integer.reverse(A << 24) & 0xff); "). reverse_bits(!.A) = B :- !:A = ((!.A /\ 0xf0_u8) >> 4) \/ ((!.A /\ 0x0f_u8) << 4), !:A = ((!.A /\ 0xcc_u8) >> 2) \/ ((!.A /\ 0x33_u8) << 2), !:A = ((!.A /\ 0xaa_u8) >> 1) \/ ((!.A /\ 0x55_u8) << 1), B = !.A. %---------------------------------------------------------------------------% rotate_left(X, N) = ( if N < 8u then unchecked_rotate_left(X, N) else func_error($pred, "rotate amount exceeds 7 bits") ). :- pragma foreign_proc("C", unchecked_rotate_left(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; // XXX clang has intrinsics for rotation -- we should use those instead. Result = (X << N) | (X >> (-N & 7)); "). :- pragma foreign_proc("C#", unchecked_rotate_left(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; Result = (byte) ((X << (int) N) | (X >> (int) (-N & 7))); "). :- pragma foreign_proc("Java", unchecked_rotate_left(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; Result = (byte) ((X << (int) N) | (X >>> (int) (-N & 7))); "). %---------------------------------------------------------------------------% rotate_right(X, N) = ( if N < 8u then unchecked_rotate_right(X, N) else func_error($pred, "rotate amount exceeds 7 bits") ). :- pragma foreign_proc("C", unchecked_rotate_right(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; Result = (X >> N) | (X << (-N & 7)); "). :- pragma foreign_proc("C#", unchecked_rotate_right(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; Result = (byte) ((X >> (int) N) | (X << (int) (-N & 7))); "). :- pragma foreign_proc("Java", unchecked_rotate_right(X::in, N::in) = (Result::out), [will_not_call_mercury, promise_pure, thread_safe], " N &= 7; Result = (byte) ((X >>> (int) N) | (X << (int) (-N & 7))); "). %---------------------------------------------------------------------------% set_bit(U, I) = ( if I < 8u then unchecked_set_bit(U, I) else func_error($pred, "bit index exceeds 7 bits") ). unchecked_set_bit(U, I) = U \/ (1u8 `unchecked_left_shift` cast_to_int(I)). clear_bit(U, I) = ( if I < 8u then unchecked_clear_bit(U, I) else func_error($pred, "bit index exceeds 7 bits") ). unchecked_clear_bit(U, I) = U /\ (\ (1u8 `unchecked_left_shift` cast_to_int(I))). flip_bit(U, I) = ( if I < 8u then unchecked_flip_bit(U, I) else func_error($pred, "bit index exceeds 7 bits") ). unchecked_flip_bit(U, I) = U `xor` (1u8 `unchecked_left_shift` cast_to_int(I)). bit_is_set(U, I) :- ( if I < 8u then unchecked_bit_is_set(U, I) else error($pred, "bit index exceeds 7 bits") ). unchecked_bit_is_set(U, I) :- U /\ (1u8 `unchecked_left_shift` cast_to_int(I)) \= 0u8. bit_is_clear(U, I) :- ( if I < 8u then unchecked_bit_is_clear(U, I) else error($pred, "bit index exceeds 7 bits") ). unchecked_bit_is_clear(U, I) :- U /\ (1u8 `unchecked_left_shift` cast_to_int(I)) = 0u8. %---------------------------------------------------------------------------% max_uint8 = 255_u8. %---------------------------------------------------------------------------% uint8_to_doc(U) = pretty_printer.uint8_to_doc(U). %---------------------------------------------------------------------------% :- end_module uint8. %---------------------------------------------------------------------------%