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/*
* MIT License
*
* Copyright (c) 2023 Christian Chapman
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <string.h>
#include "mc.h"
/* mc_reset Initialize or reset an MC buffer
* Input: mc = location of buffer to reset
*/
void mc_reset(mc_state_t * mc) {
memset(mc->b, '\0', BUFFLEN*sizeof(mc->b[0]));
mc->bidx = 0;
return;
return;
}
/* mc_input Read an input into a morse code buffer
* Input: mc = buffer to read into
* c = character to read into buffer ('.' or '-', ignored otherwise).
* If the buffer is full, reset it instead of entering the new character.
*/
void mc_input(mc_state_t * mc, char c) {
if(mc->bidx >= BUFFLEN) mc_reset(mc);
else if( ('.' == c) || ('-' == c) ) {
mc->b[mc->bidx] = c;
mc->bidx++;
}
return;
}
/* mc_dec Decode a Morse code character (descend MC_DEC_KEY[])
* Input: b = BUFFLEN-length char array with '.'s and '-'s
* Output: c = Character b represents, or '\0' if not a Morse code.
*/
char mc_dec(char b[BUFFLEN]) {
uint8_t pos = 1; // Binary tree position ('.'=0; '-'=1)
for(uint8_t idx=0; idx<BUFFLEN; idx++) {
if('.' == b[idx]) pos = 2*pos; // Descend in . direction
else if('-' == b[idx]) pos = 2*pos+1; // Descend in - direction
else break; // End of morse code segment; finished descending
}
return MC_DEC_KEY[pos-1];
}
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