OpenRTX/platform/drivers/GPS/nmea_rbuf.c

132 wiersze
4.0 KiB
C

/***************************************************************************
* Copyright (C) 2025 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN *
* Frederik Saraci IU2NRO *
* Silvano Seva IU2KWO *
* *
* 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/> *
***************************************************************************/
#include <hwconfig.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include "nmea_rbuf.h"
static inline size_t nmeaRbuf_size(struct nmeaRbuf *rbuf)
{
if(rbuf->wrPos >= rbuf->rdPos)
return rbuf->wrPos - rbuf->rdPos;
else
return CONFIG_NMEA_RBUF_SIZE + rbuf->wrPos - rbuf->rdPos;
}
void nmeaRbuf_reset(struct nmeaRbuf *rbuf)
{
rbuf->wrPos = 0;
rbuf->rdPos = 0;
rbuf->rdLimit = 0;
rbuf->filling = false;
}
int nmeaRbuf_putChar(struct nmeaRbuf *rbuf, const char c)
{
if((rbuf->filling == false) && (c == '$'))
rbuf->filling = true;
if(rbuf->filling) {
size_t next = (rbuf->wrPos + 1) % CONFIG_NMEA_RBUF_SIZE;
// No more space, drop current sentence and restart
if(next == rbuf->rdPos) {
rbuf->filling = false;
rbuf->wrPos = rbuf->rdLimit;
return -1;
}
// Append the new character
rbuf->data[rbuf->wrPos] = c;
rbuf->wrPos = next;
// Check if a full sentence is present
if(c == '\n') {
rbuf->filling = false;
rbuf->rdLimit = rbuf->wrPos;
}
}
return 0;
}
int nmeaRbuf_putSentence(struct nmeaRbuf *rbuf, const char *sentence)
{
size_t len = strlen(sentence);
size_t next = (rbuf->wrPos + len) % CONFIG_NMEA_RBUF_SIZE;
size_t free = CONFIG_NMEA_RBUF_SIZE - nmeaRbuf_size(rbuf);
// Bad-formatted string
if((sentence[0] != '$') || (sentence[len - 1] != '\n'))
return -1;
// Not enough space
if(len >= free)
return -2;
// Handle write pointer wrap-around
if((rbuf->wrPos + len) >= CONFIG_NMEA_RBUF_SIZE) {
size_t chunkSize = CONFIG_NMEA_RBUF_SIZE - rbuf->wrPos;
memcpy(&rbuf->data[rbuf->wrPos], sentence, chunkSize);
sentence += chunkSize;
len -= chunkSize;
rbuf->wrPos = 0;
}
memcpy(&rbuf->data[rbuf->wrPos], sentence, len);
rbuf->wrPos = next;
rbuf->rdLimit = next;
return 0;
}
int nmeaRbuf_getSentence(struct nmeaRbuf *rbuf, char *buf, const size_t maxLen)
{
size_t bufPos = 0;
char c;
if(rbuf->rdPos == rbuf->rdLimit)
return 0;
do {
// Pop one character from the buffer
c = rbuf->data[rbuf->rdPos];
rbuf->rdPos += 1;
rbuf->rdPos %= CONFIG_NMEA_RBUF_SIZE;
// Store it
buf[bufPos] = c;
if(bufPos < maxLen)
bufPos += 1;
} while(c != '\n');
if(bufPos == maxLen)
return -1;
return (int) bufPos;
}