add F103 PL2303 with ring buffer

F1:F103/PL2303_ringbuffer/ringbuffer.c

@@ -0,0 +1,89 @@
+/*
+ * This file is part of the pl2303 project.
+ * Copyright 2022 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * 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 <stm32f1.h>
+
+#include "ringbuffer.h"
+#include "usb.h"
+#include "usb_lib.h"
+
+// ring buffer
+static char ringbuffer[RBSIZE];
+// head - position of first data byte
+// tail - position of last data byte + 1
+// head == tail - empty! So, buffer can't store more than RBSIZE-1 bytes of data!
+static volatile int head = 0, tail = 0;
+
+static int datalen(){
+    if(tail >= head) return (tail - head);
+    else return (RBSIZE - head + tail);
+}
+static int restlen(){
+    return (RBSIZE - 1 - datalen());
+}
+
+static void mcpy(char *targ, const char *src, int l){
+    while(l--) *targ++ = *src++;
+}
+
+TRUE_INLINE void incr(volatile int *what, int n){
+    *what += n;
+    if(*what >= RBSIZE) *what -= RBSIZE;
+}
+
+int RB_read(char s[BLOCKSIZE]){
+    int l = datalen();
+    if(!l) return 0;
+    if(l > BLOCKSIZE) l = BLOCKSIZE;
+    int _1st = RBSIZE - head;
+    if(_1st > l) _1st = l;
+    if(_1st > BLOCKSIZE) _1st = BLOCKSIZE;
+    mcpy(s, ringbuffer+head, _1st);
+    if(_1st < BLOCKSIZE && l > _1st){
+        mcpy(s+_1st, ringbuffer, l-_1st);
+        incr(&head, l);
+        return l;
+    }
+    incr(&head ,_1st);
+    return _1st;
+}
+
+static int addportion(const char *str, int l){
+    int r = restlen();
+    if(l > r) l = r;
+    if(!l) return 0;
+    int _1st = RBSIZE - tail;
+    if(_1st > l) _1st = l;
+    mcpy(ringbuffer+tail, str, _1st);
+    if(_1st < l){ // add another piece from start
+        mcpy(ringbuffer, str+_1st, l-_1st);
+    }
+    incr(&tail, l);
+    return l;
+}
+
+void RB_write(const char *str, int l){
+    if(!str || !*str) return;
+    if(!usbON) return;
+    while(l){
+        if(tx_succesfull) send_next();
+        int a = addportion(str, l);
+        l -= a;
+        str += a;
+    }
+}