dpc · August 29, 2015 14:23 · Jun 19, 2015 · Jun 18, 2015 · Jun 18, 2015
diff --git a/cbuf.h b/cbuf.h
@@ -1,4 +1,3 @@
-
 #include <stddef.h>
 #include <stdint.h>
 #include <stdbool.h>

diff --git a/Makefile b/Makefile
@@ -0,0 +1,2 @@
+cbuf: cbuf.h cbuf.c
+	gcc -O3 -std=gnu99 cbuf.c -o cbuf
diff --git a/cbuf.c b/cbuf.c
@@ -0,0 +1,44 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "cbuf.h"
+
+uint8_t buf[16];
+
+int main() {
+	struct cbuf cbuf;
+	size_t cur_len = 0;
+	uint8_t put_val = 0;
+	uint8_t get_val = 0;
+
+	cbuf_init(&cbuf, buf, sizeof buf);
+
+	while (true) {
+		if (cur_len == 0) {
+			assert(cbuf_is_empty(&cbuf));
+		}
+		if (cur_len == sizeof buf) {
+			assert(cbuf_is_full(&cbuf));
+		}
+
+		if (rand() & 1) {
+			if (!cbuf_is_empty(&cbuf)) {
+				uint8_t val = cbuf_get(&cbuf);
+				assert(val == get_val++);
+				cur_len--;
+				printf("%u len: %u\n",
+				       (unsigned)val, (unsigned)
+				       cur_len);
+			}
+		} else {
+			if (!cbuf_is_full(&cbuf)) {
+				cbuf_put(&cbuf, put_val++);
+				cur_len++;
+			}
+		}
+	}
+
+
+	return 0;
+}
diff --git a/cbuf.h b/cbuf.h
@@ -0,0 +1,67 @@
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+
+/* TODO: Fix on 64 architecture */
+#define CBUF_DATA_BIT (1 << 31)
+
+/**
+ * Char circular buffer
+ */
+struct cbuf {
+	uint8_t *data;
+	size_t size;
+	size_t start;
+	size_t end;
+};
+
+
+static inline
+bool cbuf_is_empty(struct cbuf* cbuf)
+{
+	return cbuf->start == cbuf->end;
+}
+
+static inline
+bool cbuf_is_full(struct cbuf* cbuf)
+{
+	return (cbuf->start ^ cbuf->end) == CBUF_DATA_BIT;
+}
+
+static inline
+uint8_t cbuf_get(struct cbuf* cbuf)
+{
+	uint8_t ret = cbuf->data[cbuf->start & ~CBUF_DATA_BIT];
+
+	cbuf->start++;
+
+	if ((cbuf->start & ~CBUF_DATA_BIT) >= cbuf->size) {
+		cbuf->start -= cbuf->size;
+		cbuf->start ^= CBUF_DATA_BIT;
+	}
+
+	return ret;
+}
+
+static inline
+void cbuf_put(struct cbuf* cbuf, uint8_t byte)
+{
+	cbuf->data[cbuf->end & ~CBUF_DATA_BIT] = byte;
+
+	cbuf->end++;
+
+	if ((cbuf->end & ~CBUF_DATA_BIT) >= cbuf->size) {
+		cbuf->end -= cbuf->size;
+		cbuf->end ^= CBUF_DATA_BIT;
+	}
+}
+
+static inline
+void cbuf_init(struct cbuf* cbuf, uint8_t* data, size_t size)
+{
+	memset(cbuf, 0, sizeof(*cbuf));
+	cbuf->data = data;
+	cbuf->size = size;
+}
diff --git a/README.md b/README.md
@@ -0,0 +1 @@
+TBD
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		cbuf: cbuf.h cbuf.c
		gcc -O3 -std=gnu99 cbuf.c -o cbuf