98 lines
3.4 KiB
C++
98 lines
3.4 KiB
C++
/*
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UnishoxStrings.c - support library for compressed strings in Flash
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Copyright (C) 2021 Theo Arends and Stephan Hadinger
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __UNISHOX_STRINGS__
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#define __UNISHOX_STRINGS__
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#include <cstddef>
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#include <cstdint>
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#include "WString.h"
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/*******************************************************************************************/
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/*
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* UnishoxStrings compressed literal strings
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*
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* To be typically used for web UI to have multiple strings like JS, CSS, HTML
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* compressed in a single list of small strings. This is where Unishox shines.
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*
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* Strings before compression are separated with NULL chars, which makes them ready to use
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* once you know the offset in the global array.
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*
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* The list of string is marked by an empty stings, i.e. two consecutive NULL chars
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*
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* To distinguish from uncompressed templates, and to indicate the global size
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* the compressed array is prefixed with NULL and the uncompressed size * 16 bytes.
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*
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* Compressed format:
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* - Byte 00 : \00 - if non-null, then it is not compressed
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* - Byte 01 : <size16> - uncompressed size is <size16> * 16 bytes (always rounded up)
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* - Byte [] : compressed data (does not contain NULL)
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* - Byte n : \00 - final NULL
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*
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/*******************************************************************************************/
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/*******************************************************************************************/
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/*
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* This class is initialzed with either a PMEM uncompressed list of strings
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* or a PMEM unishox-compressed list of strings; in this case RAM is allocated
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* to hold the uncompressed data, until the class gets out of scope.
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*
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* To encode, use https://tasmota.hadinger.fr/util
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* and use the "Compress strings template with unishox"
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* past the C code for the strings, and copy/paste the result
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* (don't foget to rename the variable).
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*
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* Input:
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* Each string must be terminated with an explicit NULL char "\0". The list is hence
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* terminated with a double-NULL.
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*
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* Each string is then indexed as its byte offset in the whole template.
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* The offsets are computed at the same time as the compressed version.
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* You need to use the online compressor even if you don't use the comrpessed version.
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*
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* Indexes are marked as C++ comments starting with "//="
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*
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* Example input:
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* con
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* // start of strings
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* //=STRING_1
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* "This is string 1"
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* "\0"
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* //=STRING_2
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* "This is string 2"
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* "continued here"
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* "\0"
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* ;
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*
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/*******************************************************************************************/
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class UnishoxStrings {
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public:
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UnishoxStrings(const char *k_msg);
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inline const char * operator[](uint16_t i) const { return _msg + i; }
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const char * _msg = nullptr;
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String _decompressed;
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};
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#endif // __UNISHOX_STRINGS__
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