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cbor.m
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cbor.m
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% cbor.m - CBOR (RFC 7049) encoder/decoder for MATLAB
% Copyright (C) 2022 Coppelia Robotics AG
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
%
% cbor.m is courtesy of Federico Ferri
classdef cbor
methods
function obj = cbor()
fprintf('Running tests...\n');
cbor.test
clear obj
end
end
properties(Constant, Access = private)
MASK_MAJOR = 0xE0
MASK_INFO = 0x1F
UNSIGNED_INT = 0
NEGATIVE_INT = 1
BYTE_STRING = 2
TEXT_STRING = 3
ARRAY = 4
MAP = 5
SIMPLE_VALUE = 7
FALSE = 20
TRUE = 21
NULL = 22
UNDEFINED = 23
SINGLE_BYTE_EXTENSION = 24
FLOAT16 = 25
FLOAT32 = 26
FLOAT64 = 27
BREAK = 31
UINT8 = 24
UINT16 = 25
UINT32 = 26
UINT64 = 27
UNDEFINED_LENGTH = 31
end
methods(Static, Access = private)
function opts = getopts(args,varargin)
opts = struct();
for i=1:2:numel(varargin)
opts.(varargin{i}) = varargin{i+1};
end
for i=1:2:numel(args)
if isfield(opts,args{i})
opts.(args{i}) = args{i+1};
else
error('unknown option: "%s"',args{i});
end
end
end
end
methods(Static)
function [o,d1] = decode(d,varargin)
opts = cbor.getopts(varargin, ...
'array2mat', false ...
);
assert(isa(d, 'uint8'));
major = bitshift(bitand(d(1), cbor.MASK_MAJOR), -5);
info = bitand(d(1), cbor.MASK_INFO);
d1 = d(2:end);
d1 = d1(:)';
as = @(x,t) typecast(flip(x), t);
if major ~= cbor.SIMPLE_VALUE
if info < 24
info1 = double(info);
elseif info == cbor.UINT8
info1 = double(d1(1));
d1 = d1(2:end);
elseif info == cbor.UINT16
info1 = double(as(d1(1:2), 'uint16'));
d1 = d1(3:end);
elseif info == cbor.UINT32
info1 = double(as(d1(1:4), 'uint32'));
d1 = d1(5:end);
elseif info == cbor.UINT64
info1 = double(as(d1(1:8), 'uint64'));
d1 = d1(9:end);
elseif info == cbor.UNDEFINED_LENGTH
info1 = NaN;
elseif info > 27
error('malformed data (info > 27)');
end
end
if major == cbor.UNSIGNED_INT
if isnan(info1) error('malformed data (int + undefined length)'); end
o = info1;
elseif major == cbor.NEGATIVE_INT
if isnan(info1) error('malformed data (negative int + undefined length)'); end
o = -1 - info1;
elseif major == cbor.BYTE_STRING
if isnan(info1) error('undefined length byte strings are not supported by this decoder'); end
o = d1(1:info1);
d1 = d1((info1+1):end);
elseif major == cbor.TEXT_STRING
if isnan(info1) error('undefined length text strings are not supported by this decoder'); end
o = native2unicode(d1(1:info1), 'UTF-8');
d1 = d1((info1+1):end);
elseif major == cbor.ARRAY
if isnan(info1) info1 = 1e10; end
o = {};
homogeneous = true;
for i=1:info1
if d1(1) == 255 d1 = d1(2:end); break; end
[o{i}, d1] = cbor.decode(d1);
if homogeneous && i > 1 && ~strcmp(class(o{1}),class(o{i}))
homogeneous = false;
end
end
if opts.array2mat && homogeneous && (numel(o) == 0 || ~isa(o(1),'char'))
o = cell2mat(o);
end
elseif major == cbor.MAP
if isnan(info1) info1 = 1e10; end
n = {};
v = {};
for i=1:info1
if d1(1) == 255 d1 = d1(2:end); break; end
[n{i}, d1] = cbor.decode(d1);
[v{i}, d1] = cbor.decode(d1);
if n{i}(1) == '_'
% field names cannot start with underscore
n{i} = sprintf('x%s', n{i});
end
end
o = cell2struct(v, n, 2);
elseif major == cbor.SIMPLE_VALUE
if info == cbor.SINGLE_BYTE_EXTENSION
% simple value 32..255 in next byte
info = d1(1);
d1 = d1(2:end);
if info < 32 error('malformed simple value (0..31 in byte ext)'); end
end
if info == cbor.FALSE
o = false;
elseif info == cbor.TRUE
o = true;
elseif info == cbor.NULL
o = NaN;
elseif info == cbor.UNDEFINED
error('cannot decode undefined value');
elseif info == cbor.FLOAT16
f16 = as(d1(1:2), 'uint16');
d1 = d1(3:end);
% due to lack of 16-bit floats support, we decode
% IEEE 754 16-bit float manually:
sign = (-1) ^ double(bitget(f16,16));
expo = bitshift(bitand(f16,0x7C00),-10);
frac = bitand(f16,0x03FF);
if expo == 0
o = sign * 2^-14 * double(frac) / 1024;
elseif expo == 0x1F && frac == 0
o = sign * inf;
elseif expo == 0x1F && frac ~= 0
o = nan;
else
o = sign * 2^(double(expo) - 15) * (1 + double(frac) / 1024);
end
elseif info == cbor.FLOAT32
o = as(d1(1:4), 'single');
d1 = d1(5:end);
elseif info == cbor.FLOAT64
o = as(d1(1:8), 'double');
d1 = d1(9:end);
elseif info == cbor.BREAK
% not used - will peek for 255 manually where needed
error('unexpected break');
else
error('unrecognized simple value: %d', info);
end
end
end
function [d] = encode(o,varargin)
opts = cbor.getopts(varargin ...
);
HDR = @(major, info) cbor.encode({'@HDR', {}; major, info});
tobytes = @(x) flip(typecast(x, 'uint8'));
% encoding of header with simple value (length, integers, etc...):
if isa(o, 'cell') && isequal(size(o), [2, 2]) && strcmp(o{1,1}, '@HDR')
major = o{2,1};
info = o{2,2};
if info < 0
error('info value cannot be negative');
elseif info < 24 || major == cbor.SIMPLE_VALUE
d = [uint8(info)];
elseif info < 2^8
d = [cbor.UINT8, uint8(info)];
elseif info < 2^16
d = [cbor.UINT16, tobytes(uint16(info))];
elseif info < 2^32
d = [cbor.UINT32, tobytes(uint32(info))];
elseif info < 2^64
d = [cbor.UINT64, tobytes(uint64(info))];
else
error('info value too big: %d', info);
end
d(1) = uint8( ...
bitor( ...
bitshift(uint8(major), 5), ...
bitand(cbor.MASK_INFO, uint8(d(1))) ...
) ...
);
return
end
% encode NaN as null
if isnumeric(o) && numel(o) == 1 && isnan(o)
d = [HDR(cbor.SIMPLE_VALUE, cbor.NULL)];
return
end
% array types
l = numel(o);
if l == 0
d = [HDR(cbor.ARRAY, 0)];
return
elseif (iscell(o) || l > 1) && isvector(o)
if isa(o, 'char')
% char vector is handled later as a string
elseif isa(o, 'uint8')
% uint8 vector is used for binary data
d = [HDR(cbor.BYTE_STRING, l), o(:)'];
return
elseif iscell(o)
% cell array encodes as array
d = [HDR(cbor.ARRAY, l)];
for i=1:l; d = [d, cbor.encode(o{i})]; end
return
else
% regular vector encodes as array
d = [HDR(cbor.ARRAY, l)];
for i=1:l; d = [d, cbor.encode(o(i))]; end
return
end
elseif l > 1
error('cannot encode nd-matrix');
end
% basic types:
if isa(o, 'struct')
% map
n = fieldnames(o);
info = struct2cell(o);
l = numel(n);
d = [HDR(cbor.MAP, l)];
for i=1:l; d = [d, cbor.encode(n{i}), cbor.encode(info{i})]; end
elseif isa(o, 'single')
if mod(o, 1) == 0; d = cbor.encode(int64(o)); return; end
d = [HDR(cbor.SIMPLE_VALUE, cbor.FLOAT32), tobytes(o)];
elseif isa(o, 'double')
if mod(o, 1) == 0; d = cbor.encode(int64(o)); return; end
d = [HDR(cbor.SIMPLE_VALUE, cbor.FLOAT64), tobytes(o)];
elseif isa(o, 'integer')
if o < 0
d = [HDR(cbor.NEGATIVE_INT, -1 - o)];
else
d = [HDR(cbor.UNSIGNED_INT, o)];
end
elseif isa(o, 'char')
u = unicode2native(o, 'UTF-8');
l = numel(u);
d = [HDR(cbor.TEXT_STRING, l), u];
elseif isa(o, 'string')
d = cbor.encode(char(o));
elseif isa(o, 'logical')
if o
d = [HDR(cbor.SIMPLE_VALUE, cbor.TRUE)];
else
d = [HDR(cbor.SIMPLE_VALUE, cbor.FALSE)];
end
else
error('unsupported type: %s', class(o));
end
end
function test()
% encode/decode to hex-string:
enc = @(o) sprintf('%02x', cbor.encode(o));
dec = @(s) cbor.decode(uint8(sscanf(s, '%02x')'));
% like isequaln(), but can mix cell with num arrays
isequalx = @(a,b) isequaln(a,b) ...
|| (iscell(a) && ~iscell(b) && isequaln(a,num2cell(b))) ...
|| (~iscell(a) && iscell(b) && isequaln(num2cell(a),b));
T = @(a,b) assert(strcmpi(enc(a),b) && isequalx(a,dec(b)));
T(false,'F4');
T(true,'F5');
T(NaN,'F6');
T(1,'01');
T(100,'1864');
T(1000,'1903E8');
T(1000000,'1A000F4240');
T(1000000000000,'1B000000E8D4A51000');
T(23,'17');
T(24,'1818');
T(32,'1820');
T(2^8,'190100');
T(2^16,'1A00010000');
T(2^32,'1B0000000100000000');
T(3.14159,'FB400921F9F01B866E');
T('abc','63616263');
T(struct('a', 10.52),'A16161FB40250A3D70A3D70A');
T(struct('b', true),'A16162F5');
T(struct('c', 'foo'),'A1616363666F6F');
T(struct('a', 10.52, 'b', true, 'c', 'foo'),'A36161FB40250A3D70A3D70A6162F5616363666F6F');
T(struct('x', struct('y', struct('z', 42))),'A16178A16179A1617A182A');
T({1,2,3},'83010203');
T([1,2,3],'83010203');
T({1.23,4.56,7.89},'83FB3FF3AE147AE147AEFB40123D70A3D70A3DFB401F8F5C28F5C28F');
T(num2cell(2.^(0:16)),'9101020408101820184018801901001902001904001908001910001920001940001980001A00010000');
T(["a","b","c"],'83616161626163');
T({"a","b","c"},'83616161626163');
T({'a','b','c'},'83616161626163');
T({0,"b",true,-1,3.98},'85006162F520FB400FD70A3D70A3D7');
T(uint8([1,2,3]),'43010203');
T(uint8(zeros([1,32])),'58200000000000000000000000000000000000000000000000000000000000000000');
T({true,false,false,true,false},'85F5F4F4F5F4');
T([true,false,false,true,false],'85F5F4F4F5F4');
T([NaN,NaN],'82F6F6');
T({1},'8101');
% testcases from https://en.wikipedia.org/wiki/Half-precision_floating-point_format#Half_precision_examples
Td = @(a,b) assert(abs(a-dec(b))<1e-8);
Td(1.5,'F93E00');
Td(0,'F90000');
Td(0.000000059604645,'F90001');
Td(0.000060975552,'F903FF');
Td(0.00006103515625,'F90400');
Td(0.33325195,'F93555');
Td(0.99951172,'F93BFF');
Td(1,'F93C00');
Td(1.00097656,'F93C01');
Td(65504,'F97BFF');
assert(inf==dec('F97C00'));
assert(-inf==dec('F9FC00'));
Td(0,'F98000'); % -0
Td(-2,'F9C000');
% test for more than 24 items:
T(struct('a', 1000, 'b', 1001, 'c', 1002, 'd', 1003, 'e', 1004, 'f', 1005, 'g', 1006, 'h', 1007, 'i', 1008, 'j', 1009, 'k', 1010, 'l', 1011, 'm', 1012, 'n', 1013, 'o', 1014, 'p', 1015, 'q', 1016, 'r', 1017, 's', 1018, 't', 1019, 'u', 1020, 'v', 1021, 'w', 1022, 'x', 1023, 'y', 1024, 'z', 1025),'B81A61611903E861621903E961631903EA61641903EB61651903EC61661903ED61671903EE61681903EF61691903F0616A1903F1616B1903F2616C1903F3616D1903F4616E1903F5616F1903F661701903F761711903F861721903F961731903FA61741903FB61751903FC61761903FD61771903FE61781903FF6179190400617A190401');
% indefinite-length array and map items: (decode-only)
assert(isequalx(struct('a', 1, 'b', 2), dec('BF616101616202FF')));
assert(isequalx([1,2,3], dec('9F010203FF')));
fprintf('All tests passed successfully.\n');
end
end
end