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Diffstat (limited to 'lib/stdlib/src/erl_bits.erl')
| -rw-r--r-- | lib/stdlib/src/erl_bits.erl | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/lib/stdlib/src/erl_bits.erl b/lib/stdlib/src/erl_bits.erl new file mode 100644 index 0000000000..62f6d00fae --- /dev/null +++ b/lib/stdlib/src/erl_bits.erl @@ -0,0 +1,186 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 1999-2009. All Rights Reserved. +%% +%% The contents of this file are subject to the Erlang Public License, +%% Version 1.1, (the "License"); you may not use this file except in +%% compliance with the License. You should have received a copy of the +%% Erlang Public License along with this software. If not, it can be +%% retrieved online at http://www.erlang.org/. +%% +%% Software distributed under the License is distributed on an "AS IS" +%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +%% the License for the specific language governing rights and limitations +%% under the License. +%% +%% %CopyrightEnd% +%% + +-module(erl_bits). + +-export([system_bittypes/0, + system_bitdefault/0, + set_bit_type/2, + as_list/1]). + +-include("../include/erl_bits.hrl"). + +%% Dummies. + +-spec system_bitdefault() -> 'no_system_bitdefault'. + +system_bitdefault() -> no_system_bitdefault. + +-spec system_bittypes() -> 'no_system_types'. + +system_bittypes() -> no_system_types. + +-spec as_list(#bittype{}) -> + [bt_endian() | bt_sign() | bt_type() | {'unit', 'undefined' | bt_unit()}]. + +as_list(Bt) -> + [Bt#bittype.type,{unit,Bt#bittype.unit},Bt#bittype.sign,Bt#bittype.endian]. + +%% XXX: tuple() below stands for what's produced by the parser +%% {integer,L,M} | {var,L,VAR} | {atom,L,ATOM} | {op,L,OP,OP1,OP2} | ... +-type size() :: 'all' | 'unknown' | non_neg_integer() | tuple(). % XXX: REFINE +-type type() :: 'bytes' | 'bitstring' | 'bits' + | bt_type() | bt_endian() | bt_sign() + | {'unit', 'undefined' | bt_unit()}. + +-spec set_bit_type('default' | size(), 'default' | [type()]) -> + {'ok', 'undefined' | size(), #bittype{}} | + {'error', {'undefined_bittype', term()}} | + {'error', {'bittype_mismatch', term(), term(), string()}}. + +set_bit_type(Size, default) -> + set_bit_type(Size, []); +set_bit_type(Size, TypeList) -> + try + #bittype{type=Type,unit=Unit,sign=Sign,endian=Endian} = + set_bit(TypeList), + apply_defaults(Type, Size, Unit, Sign, Endian) + catch + throw:Error -> Error + end. + +set_bit([]) -> #bittype{}; +set_bit([H|T]) -> set_bit_1(T, type_to_record(H)). + +set_bit_1([T0|Ts], Bt0) -> + Type = type_to_record(T0), + Bt = merge_bittype(Type, Bt0), + set_bit_1(Ts, Bt); +set_bit_1([], Bt) -> Bt. + +type_to_record(integer) -> #bittype{type = integer}; +type_to_record(utf8) -> #bittype{type = utf8}; +type_to_record(utf16) -> #bittype{type = utf16}; +type_to_record(utf32) -> #bittype{type = utf32}; +type_to_record(float) -> #bittype{type = float}; +type_to_record(binary) -> #bittype{type = binary}; +type_to_record(bytes) -> #bittype{type = binary, unit = 8}; +type_to_record(bitstring) -> #bittype{type = binary, unit = 1}; +type_to_record(bits) -> #bittype{type = binary, unit = 1}; + +type_to_record({unit,undefined}) -> + #bittype{unit=undefined}; +type_to_record({unit,Sz}) when is_integer(Sz), Sz > 0, Sz =< 256 -> + #bittype{unit=Sz}; + +type_to_record(big) -> #bittype{endian = big}; +type_to_record(little) -> #bittype{endian = little}; +type_to_record(native) -> #bittype{endian = native}; + +type_to_record(signed) -> #bittype{sign = signed}; +type_to_record(unsigned) -> #bittype{sign = unsigned}; + +type_to_record(Name) -> throw({error,{undefined_bittype,Name}}). + +%% +%% Merge two bit type specifications. +%% +merge_bittype(B1, B2) -> + Endian = merge_field(B1#bittype.endian, B2#bittype.endian, endianness), + Sign = merge_field(B1#bittype.sign, B2#bittype.sign, sign), + Type = merge_field(B1#bittype.type, B2#bittype.type, type), + Unit = merge_field(B1#bittype.unit, B2#bittype.unit, unit), + #bittype{type=Type,unit=Unit,endian=Endian,sign=Sign}. + +merge_field(undefined, B, _) -> B; +merge_field(A, undefined, _) -> A; +merge_field(A, A, _) -> A; +merge_field(X, Y, What) -> + throw({error,{bittype_mismatch,X,Y,atom_to_list(What)}}). + +%% +%% Defaults are as follows. +%% +%% The default is integer. +%% The default size is 'all' for binaries, 8 for integers, 64 for floats. +%% No unit must be given if the size is not given. +%% The default unit size is 8 for binaries, and 1 for integers and floats. +%% The default sign is always unsigned. +%% The default endian is always big. +%% + +apply_defaults(undefined, Size, Unit, Sign, Endian) -> %default type + apply_defaults(integer, Size, Unit, Sign, Endian); + +apply_defaults(binary, default, Unit, Sign, Endian) -> %default size + %% check_unit(Unit), removed to allow bitlevel binaries + apply_defaults(binary, all, Unit, Sign, Endian); +apply_defaults(integer, default, Unit, Sign, Endian) -> + check_unit(Unit), + apply_defaults(integer, 8, 1, Sign, Endian); +apply_defaults(utf8=Type, default, Unit, Sign, Endian) -> + apply_defaults(Type, undefined, Unit, Sign, Endian); +apply_defaults(utf16=Type, default, Unit, Sign, Endian) -> + apply_defaults(Type, undefined, Unit, Sign, Endian); +apply_defaults(utf32=Type, default, Unit, Sign, Endian) -> + apply_defaults(Type, undefined, Unit, Sign, Endian); +apply_defaults(float, default, Unit, Sign, Endian) -> + check_unit(Unit), + apply_defaults(float, 64, 1, Sign, Endian); + +apply_defaults(binary, Size, undefined, Sign, Endian) -> %default unit + apply_defaults(binary, Size, 8, Sign, Endian); +apply_defaults(integer, Size, undefined, Sign, Endian) -> + apply_defaults(integer, Size, 1, Sign, Endian); +apply_defaults(float, Size, undefined, Sign, Endian) -> + apply_defaults(float, Size, 1, Sign, Endian); + +apply_defaults(Type, Size, Unit, undefined, Endian) -> %default sign + apply_defaults(Type, Size, Unit, unsigned, Endian); + +apply_defaults(Type, Size, Unit, Sign, undefined) -> %default endian + apply_defaults(Type, Size, Unit, Sign, big); + +apply_defaults(Type, Size, Unit, Sign, Endian) -> %done + check_size_unit(Type, Size, Unit), + {ok,Size,#bittype{type=Type,unit=Unit,sign=Sign,endian=Endian}}. + +check_size_unit(utf8, Size, Unit) -> + check_size_unit_1(Size, Unit); +check_size_unit(utf16, Size, Unit) -> + check_size_unit_1(Size, Unit); +check_size_unit(utf32, Size, Unit) -> + check_size_unit_1(Size, Unit); +check_size_unit(_, _, _) -> ok. + +check_size_unit_1(Size, Unit) -> + case Size of + default -> ok; + undefined -> ok; + {atom,_,undefined} -> ok; + {value,_,undefined} -> ok; + _ -> throw({error,utf_bittype_size_or_unit}) + end, + case Unit of + undefined -> ok; + _ -> throw({error,utf_bittype_size_or_unit}) + end. + +check_unit(undefined) -> ok; +check_unit(_) -> throw({error,bittype_unit}). |