py/ringbuf: Add helpers for put16/get16.

1 files changed, 66 insertions, 0 deletions

diff --git a/py/ringbuf.c b/py/ringbuf.c
new file mode 100644
index 000000000..8795e1eda
--- /dev/null
+++ b/py/ringbuf.c
@@ -0,0 +1,66 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Jim Mussared
+ *
+ * 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 "ringbuf.h"
+
+int ringbuf_get16(ringbuf_t *r) {
+    if (r->iget == r->iput) {
+        return -1;
+    }
+    uint32_t iget_a = r->iget + 1;
+    if (iget_a == r->size) {
+        iget_a = 0;
+    }
+    if (iget_a == r->iput) {
+        return -1;
+    }
+    uint16_t v = (r->buf[r->iget] << 8) | (r->buf[iget_a]);
+    r->iget = iget_a + 1;
+    if (r->iget == r->size) {
+        r->iget = 0;
+    }
+    return v;
+}
+
+int ringbuf_put16(ringbuf_t *r, uint16_t v) {
+    uint32_t iput_a = r->iput + 1;
+    if (iput_a == r->size) {
+        iput_a = 0;
+    }
+    if (iput_a == r->iget) {
+        return -1;
+    }
+    uint32_t iput_b = iput_a + 1;
+    if (iput_b == r->size) {
+        iput_b = 0;
+    }
+    if (iput_b == r->iget) {
+        return -1;
+    }
+    r->buf[r->iput] = (v >> 8) & 0xff;
+    r->buf[iput_a] = v & 0xff;
+    r->iput = iput_b;
+    return 0;
+}