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Diffstat (limited to 'lib/asn1/src/asn1rtt_real_common.erl')
| -rw-r--r-- | lib/asn1/src/asn1rtt_real_common.erl | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/lib/asn1/src/asn1rtt_real_common.erl b/lib/asn1/src/asn1rtt_real_common.erl new file mode 100644 index 0000000000..540f0d60a5 --- /dev/null +++ b/lib/asn1/src/asn1rtt_real_common.erl @@ -0,0 +1,292 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2012. 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(asn1rtt_real_common). + +-export([encode_real/1,decode_real/1, + ber_encode_real/1]). + +%%============================================================================ +%% +%% Real value, ITU_T X.690 Chapter 8.5 +%%============================================================================ +%% +%% encode real value +%%============================================================================ + +ber_encode_real(0) -> + {[],0}; +ber_encode_real('PLUS-INFINITY') -> + {[64],1}; +ber_encode_real('MINUS-INFINITY') -> + {[65],1}; +ber_encode_real(Val) when is_tuple(Val); is_list(Val) -> + encode_real(Val). + +%%%%%%%%%%%%%% +%% only base 2 encoding! +%% binary encoding: +%% +------------+ +------------+ +-+-+-+-+---+---+ +%% | (tag)9 | | n + p + 1 | |1|S|BB |FF |EE | +%% +------------+ +------------+ +-+-+-+-+---+---+ +%% +%% +------------+ +------------+ +%% | | | | +%% +------------+ ...+------------+ +%% n octets for exponent +%% +%% +------------+ +------------+ +%% | | | | +%% +------------+ ...+------------+ +%% p octets for pos mantissa +%% +%% S is 0 for positive sign +%% 1 for negative sign +%% BB: encoding base, 00 = 2, (01 = 8, 10 = 16) +%% 01 and 10 not used +%% FF: scale factor 00 = 0 (used in base 2 encoding) +%% EE: encoding of the exponent: +%% 00 - on the following octet +%% 01 - on the 2 following octets +%% 10 - on the 3 following octets +%% 11 - encoding of the length of the two's-complement encoding of +%% exponent on the following octet, and two's-complement +%% encoding of exponent on the other octets. +%% +%% In DER and base 2 encoding the mantissa is encoded as value 0 or +%% bit shifted until it is an odd number. Thus, do this for BER as +%% well. + +encode_real(Real) -> + encode_real([], Real). + +encode_real(_C, {Mantissa, Base, Exponent}) when Base =:= 2 -> +%% io:format("Mantissa: ~w Base: ~w, Exp: ~w~n",[Man, Base, Exp]), + {Man,ExpAdd} = truncate_zeros(Mantissa), %% DER adjustment + Exp = Exponent + ExpAdd, + OctExp = if Exp >= 0 -> list_to_binary(encode_pos_integer(Exp, [])); + true -> list_to_binary(encode_neg_integer(Exp, [])) + end, +%% ok = io:format("OctExp: ~w~n",[OctExp]), + SignBit = if Man > 0 -> 0; % bit 7 is pos or neg, no Zeroval + true -> 1 + end, +%% ok = io:format("SignBitMask: ~w~n",[SignBitMask]), + SFactor = 0, + OctExpLen = size(OctExp), + if OctExpLen > 255 -> + exit({error,{asn1, {to_big_exp_in_encode_real, OctExpLen}}}); + true -> true %% make real assert later.. + end, + {LenCode, EOctets} = case OctExpLen of % bit 2,1 + 1 -> {0, OctExp}; + 2 -> {1, OctExp}; + 3 -> {2, OctExp}; + _ -> {3, <<OctExpLen, OctExp/binary>>} + end, + BB = 0, %% 00 for base 2 + FirstOctet = <<1:1,SignBit:1,BB:2,SFactor:2,LenCode:2>>, + OctMantissa = if Man > 0 -> list_to_binary(real_mininum_octets(Man)); + true -> list_to_binary(real_mininum_octets(-(Man))) % signbit keeps track of sign + end, + %% ok = io:format("LenMask: ~w EOctets: ~w~nFirstOctet: ~w OctMantissa: ~w OctExpLen: ~w~n", [LenMask, EOctets, FirstOctet, OctMantissa, OctExpLen]), + Bin = <<FirstOctet/binary, EOctets/binary, OctMantissa/binary>>, + {Bin, size(Bin)}; +encode_real(C, {Mantissa,Base,Exponent}) + when Base =:= 10, is_integer(Mantissa), is_integer(Exponent) -> + %% always encode as NR3 due to DER on the format + %% mmmm.Eseeee where + %% m := digit + %% s := '-' | '+' | [] + %% '+' only allowed in +0 + %% e := digit + %% ex: 1234.E-5679 + ManStr = integer_to_list(Mantissa), + + encode_real_as_string(C,ManStr,Exponent); +encode_real(_C, {_,Base,_}) -> + exit({error,{asn1, {encode_real_non_supported_encoding, Base}}}); +%% base 10 +encode_real(C, Real) when is_list(Real) -> + %% The Real string may come in as a NR1, NR2 or NR3 string. + {Mantissa, Exponent} = + case string:tokens(Real,"Ee") of + [NR2] -> + {NR2,0}; + [NR3MB,NR3E] -> + %% remove beginning zeros + {NR3MB,list_to_integer(NR3E)} + end, + + %% .Decimal | Number | Number.Decimal + ZeroDecimal = + fun("0") -> ""; + (L) -> L + end, + {NewMantissa,LenDecimal} = + case Mantissa of + [$.|Dec] -> + NewMan = remove_trailing_zeros(Dec), + {NewMan,length(ZeroDecimal(NewMan))}; + _ -> + case string:tokens(Mantissa,",.") of + [Num] -> %% No decimal-mark + {integer_to_list(list_to_integer(Num)),0}; + [Num,Dec] -> + NewDec = ZeroDecimal(remove_trailing_zeros(Dec)), + NewMan = integer_to_list(list_to_integer(Num)) ++ NewDec, + {integer_to_list(list_to_integer(NewMan)), + length(NewDec)} + end + end, + + encode_real_as_string(C, NewMantissa, Exponent - LenDecimal). + +encode_real_as_string(_C, Mantissa, Exponent) + when is_list(Mantissa), is_integer(Exponent) -> + %% Remove trailing zeros in Mantissa and add this to Exponent + TruncMant = remove_trailing_zeros(Mantissa), + + ExpIncr = length(Mantissa) - length(TruncMant), + + ExpStr = integer_to_list(Exponent + ExpIncr), + + ExpBin = + case ExpStr of + "0" -> + <<"E+0">>; + _ -> + ExpB = list_to_binary(ExpStr), + <<$E,ExpB/binary>> + end, + ManBin = list_to_binary(TruncMant), + NR3 = 3, + {<<NR3,ManBin/binary,$.,ExpBin/binary>>, + 2 + byte_size(ManBin) + byte_size(ExpBin)}. + +remove_trailing_zeros(IntStr) -> + case lists:dropwhile(fun($0)-> true; + (_) -> false + end, lists:reverse(IntStr)) of + [] -> + "0"; + ReversedIntStr -> + lists:reverse(ReversedIntStr) + end. + +truncate_zeros(Num) -> + truncate_zeros(Num, 0). +truncate_zeros(0, Sum) -> + {0,Sum}; +truncate_zeros(M, Sum) -> + case M band 16#f =:= M band 16#e of + true -> truncate_zeros(M bsr 1, Sum+1); + _ -> {M,Sum} + end. + + +%%============================================================================ +%% decode real value +%% +%% decode_real([OctetBufferList], tuple|value, tag|notag) -> +%% {{Mantissa, Base, Exp} | realval | PLUS-INFINITY | MINUS-INFINITY | 0, +%% RestBuff} +%% +%% only for base 2 decoding sofar!! +%%============================================================================ + +decode_real(Buffer) -> + Sz = byte_size(Buffer), + {RealVal,<<>>,Sz} = decode_real2(Buffer, [], Sz, 0), + RealVal. + +decode_real2(Buffer, _C, 0, _RemBytes) -> + {0,Buffer}; +decode_real2(Buffer0, _C, Len, RemBytes1) -> + <<First, Buffer2/binary>> = Buffer0, + if + First =:= 2#01000000 -> {'PLUS-INFINITY', Buffer2}; + First =:= 2#01000001 -> {'MINUS-INFINITY', Buffer2}; + First =:= 1 orelse First =:= 2 orelse First =:= 3 -> + %% charcter string encoding of base 10 + {NRx,Rest} = split_binary(Buffer2,Len-1), + {binary_to_list(NRx),Rest,Len}; + true -> + %% have some check here to verify only supported bases (2) + %% not base 8 or 16 + <<_B7:1,Sign:1,BB:2,_FF:2,EE:2>> = <<First>>, + Base = + case BB of + 0 -> 2; % base 2, only one so far + _ -> exit({error,{asn1, {non_supported_base, BB}}}) + end, + {FirstLen, {Exp, Buffer3,_Rb2}, RemBytes2} = + case EE of + 0 -> {2, decode_integer2(1, Buffer2, RemBytes1), RemBytes1+1}; + 1 -> {3, decode_integer2(2, Buffer2, RemBytes1), RemBytes1+2}; + 2 -> {4, decode_integer2(3, Buffer2, RemBytes1), RemBytes1+3}; + 3 -> + <<ExpLen1,RestBuffer/binary>> = Buffer2, + { ExpLen1 + 2, + decode_integer2(ExpLen1, RestBuffer, RemBytes1), + RemBytes1+ExpLen1} + end, + %% io:format("FirstLen: ~w, Exp: ~w, Buffer3: ~w ~n", + + Length = Len - FirstLen, + <<LongInt:Length/unit:8,RestBuff/binary>> = Buffer3, + {{Mantissa, Buffer4}, RemBytes3} = + if Sign =:= 0 -> + %% io:format("sign plus~n"), + {{LongInt, RestBuff}, 1 + Length}; + true -> + %% io:format("sign minus~n"), + {{-LongInt, RestBuff}, 1 + Length} + end, + {{Mantissa, Base, Exp}, Buffer4, RemBytes2+RemBytes3} + end. + +encode_pos_integer(0, [B|_Acc]=L) when B < 128 -> + L; +encode_pos_integer(N, Acc) -> + encode_pos_integer(N bsr 8, [N band 16#ff| Acc]). + +encode_neg_integer(-1, [B1|_T]=L) when B1 > 127 -> + L; +encode_neg_integer(N, Acc) -> + encode_neg_integer(N bsr 8, [N band 16#ff|Acc]). + + +%% Val must be >= 0 +real_mininum_octets(Val) -> + real_mininum_octets(Val, []). + +real_mininum_octets(0, Acc) -> + Acc; +real_mininum_octets(Val, Acc) -> + real_mininum_octets(Val bsr 8, [Val band 16#FF | Acc]). + +%% decoding postitive integer values. +decode_integer2(Len, <<0:1,_:7,_Bs/binary>> = Bin, RemovedBytes) -> + <<Int:Len/unit:8,Buffer2/binary>> = Bin, + {Int,Buffer2,RemovedBytes}; +%% decoding negative integer values. +decode_integer2(Len, <<1:1,B2:7,Bs/binary>>, RemovedBytes) -> + <<N:Len/unit:8,Buffer2/binary>> = <<B2,Bs/binary>>, + Int = N - (1 bsl (8 * Len - 1)), + {Int,Buffer2,RemovedBytes}. |