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-rw-r--r--ringbuf.h79
1 files changed, 79 insertions, 0 deletions
diff --git a/ringbuf.h b/ringbuf.h
new file mode 100644
index 0000000..6251d6c
--- /dev/null
+++ b/ringbuf.h
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+/*
+ * ringbuf.h
+ * ---------
+ * Ring buffers for more reliable UART receives.
+ *
+ * Copyright (c) 2016, NORDUnet A/S All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * - Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the NORDUnet nor the names of its contributors may
+ * be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef RINGBUF_SIZE
+#define RINGBUF_SIZE 256
+#endif
+
+typedef struct {
+ int ridx;
+ volatile int widx;
+ uint8_t buf[RINGBUF_SIZE];
+} ringbuf_t;
+
+inline void ringbuf_init(ringbuf_t *rb)
+{
+ memset(rb, 0, sizeof(*rb));
+}
+
+inline int ringbuf_read_char(ringbuf_t *rb, uint8_t *c)
+{
+ if (rb->ridx != rb->widx) {
+ *c = rb->buf[rb->ridx];
+ if (++rb->ridx >= sizeof(rb->buf))
+ rb->ridx = 0;
+ return 1;
+ }
+ return 0;
+}
+
+inline void ringbuf_write_char(ringbuf_t *rb, uint8_t c)
+{
+ rb->buf[rb->widx] = c;
+ if (++rb->widx >= sizeof(rb->buf))
+ rb->widx = 0;
+}
+
+inline int ringbuf_empty(ringbuf_t *rb)
+{
+ return (rb->ridx == rb->widx);
+}
+
+inline int ringbuf_count(ringbuf_t *rb)
+{
+ int len = rb->widx - rb->ridx;
+ if (len < 0)
+ len += sizeof(rb->buf);
+ return len;
+}