mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-11-27 10:06:13 +01:00
97 lines
3.5 KiB
C++
97 lines
3.5 KiB
C++
/*
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* © 2024 Vincent Hamp and Chris Harlow
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* All rights reserved.
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*
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* This file is part of CommandStation-EX
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*
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* This 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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*
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* It 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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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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/* Reader be aware:
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This function implements the _hk data type so that a string keyword
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is hashed to the same value as the DCCEXParser uses to hash incoming
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keywords.
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Thus "MAIN"_hk generates exactly the same run time vakue
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as const int16_t HASH_KEYWORD_MAIN=11339
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*/
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#ifndef KeywordHasher_h
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#define KeywordHasher_h
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#include <Arduino.h>
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constexpr uint16_t CompiletimeKeywordHasher(const char * sv, uint16_t running=0) {
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return (*sv==0) ? running : CompiletimeKeywordHasher(sv+1,
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(*sv >= '0' && *sv <= '9')
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? (10*running+*sv-'0') // Numeric hash
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: ((running << 5) + running) ^ *sv
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); //
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}
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constexpr int16_t operator""_hk(const char * keyword, size_t len)
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{
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return (int16_t) CompiletimeKeywordHasher(keyword,len*0);
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}
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/* Some historical values for testing:
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const int16_t HASH_KEYWORD_MAIN = 11339;
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const int16_t HASH_KEYWORD_SLOW = -17209;
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const int16_t HASH_KEYWORD_SPEED28 = -17064;
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const int16_t HASH_KEYWORD_SPEED128 = 25816;
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*/
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static_assert("MAIN"_hk == 11339,"Keyword hasher error");
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static_assert("SLOW"_hk == -17209,"Keyword hasher error");
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static_assert("SPEED28"_hk == -17064,"Keyword hasher error");
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static_assert("SPEED128"_hk == 25816,"Keyword hasher error");
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// Compile time converter from "abcd"_s7 to the 7 segment nearest equivalent
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constexpr uint8_t seg7Digits[]={
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0b00111111,0b00000110,0b01011011,0b01001111, // 0..3
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0b01100110,0b01101101,0b01111101,0b00000111, // 4..7
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0b01111111,0b01101111 // 8..9
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};
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constexpr uint8_t seg7Letters[]={
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0b01110111,0b01111100,0b00111001,0b01011110, // ABCD
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0b01111001,0b01110001,0b00111101,0b01110110, // EFGH
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0b00000100,0b00011110,0b01110010,0b00111000, //IJKL
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0b01010101,0b01010100,0b01011100,0b01110011, // MNOP
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0b10111111,0b01010000,0b01101101,0b01111000, // QRST
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0b00111110,0b00011100,0b01101010,0b01001001, //UVWX
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0b01100110,0b01011011 //YZ
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};
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constexpr uint8_t seg7Space=0b00000000;
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constexpr uint8_t seg7Minus=0b01000000;
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constexpr uint8_t seg7Equals=0b01001000;
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constexpr uint32_t CompiletimeSeg7(const char * sv, uint32_t running, size_t rlen) {
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return (*sv==0 || rlen==0) ? running << (8*rlen) : CompiletimeSeg7(sv+1,
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(*sv >= '0' && *sv <= '9') ? (running<<8) | seg7Digits[*sv-'0'] :
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(*sv >= 'A' && *sv <= 'Z') ? (running<<8) | seg7Letters[*sv-'A'] :
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(*sv >= 'a' && *sv <= 'z') ? (running<<8) | seg7Letters[*sv-'a'] :
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(*sv == '-') ? (running<<8) | seg7Minus :
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(*sv == '=') ? (running<<8) | seg7Equals :
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(running<<8) | seg7Space,
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rlen-1
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); //
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}
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constexpr uint32_t operator""_s7(const char * keyword, size_t len)
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{
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return CompiletimeSeg7(keyword,0*len,4);
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}
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#endif
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