mirror of
https://github.com/eddyem/stm32samples.git
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80 lines
2.2 KiB
C
80 lines
2.2 KiB
C
/*
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* This file is part of the pl2303 project.
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* Copyright 2022 Edward V. Emelianov <edward.emelianoff@gmail.com>.
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*
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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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*
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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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*
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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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#include <stm32f1.h>
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#include "ringbuffer.h"
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#include "usb.h"
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#include "usb_lib.h"
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// ring buffer
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static char ringbuffer[RBSIZE];
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// head - position of first data byte
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// tail - position of last data byte + 1
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// head == tail - empty! So, buffer can't store more than RBSIZE-1 bytes of data!
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static volatile int head = 0, tail = 0;
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static int datalen(){
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if(tail >= head) return (tail - head);
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else return (RBSIZE - head + tail);
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}
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static int restlen(){
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return (RBSIZE - 1 - datalen());
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}
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static void mcpy(char *targ, const char *src, int l){
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while(l--) *targ++ = *src++;
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}
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TRUE_INLINE void incr(volatile int *what, int n){
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*what += n;
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if(*what >= RBSIZE) *what -= RBSIZE;
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}
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int RB_read(char s[BLOCKSIZE]){
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int l = datalen();
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if(!l) return 0;
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if(l > BLOCKSIZE) l = BLOCKSIZE;
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int _1st = RBSIZE - head;
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if(_1st > l) _1st = l;
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if(_1st > BLOCKSIZE) _1st = BLOCKSIZE;
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mcpy(s, ringbuffer+head, _1st);
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if(_1st < BLOCKSIZE && l > _1st){
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mcpy(s+_1st, ringbuffer, l-_1st);
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incr(&head, l);
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return l;
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}
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incr(&head ,_1st);
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return _1st;
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}
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int RB_write(const char *str, int l){
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int r = restlen();
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if(l > r) l = r;
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if(!l) return 0;
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int _1st = RBSIZE - tail;
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if(_1st > l) _1st = l;
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mcpy(ringbuffer+tail, str, _1st);
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if(_1st < l){ // add another piece from start
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mcpy(ringbuffer, str+_1st, l-_1st);
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}
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incr(&tail, l);
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return l;
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}
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