From b13efce73e506b0feb4bb7c275c273a54ae6e716 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Tue, 22 Oct 2019 15:04:45 +0200
Subject: Change license and style, reorganise file, make makefile portable,
 and fix bugs
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 types-ring.c | 193 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)
 create mode 100644 types-ring.c

(limited to 'types-ring.c')

diff --git a/types-ring.c b/types-ring.c
new file mode 100644
index 0000000..6cceea1
--- /dev/null
+++ b/types-ring.c
@@ -0,0 +1,193 @@
+/* See LICENSE file for copyright and license details. */
+#include "types-ring.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+/**
+ * Initialise a ring buffer
+ * 
+ * @param  this  The ring buffer
+ */
+void
+ring_initialise(struct ring *restrict this)
+{
+	this->start  = 0;
+	this->end    = 0;
+	this->size   = 0;
+	this->buffer = NULL;
+}
+
+
+#if defined(__clang__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wcast-align"
+#endif
+
+
+/**
+ * Marshal a ring buffer
+ * 
+ * @param   this  The ring buffer
+ * @param   buf   Output buffer for the marshalled data,
+ *                `NULL` to only measure how large buffer
+ *                is needed
+ * @return        The number of marshalled bytes
+ */
+size_t
+ring_marshal(const struct ring *restrict this, void *restrict buf)
+{
+	size_t off = 0, n = this->end - this->start;
+	char *bs = buf;
+
+	if (bs)
+		*(size_t *)&bs[off] = n;
+	off += sizeof(size_t);
+
+	if (bs)
+		memcpy(&bs[off], this->buffer + this->start, n);
+	off += n;
+
+	return off;
+}
+
+
+/**
+ * Unmarshal a ring buffer
+ * 
+ * @param   this  Output parameter for the ring buffer
+ * @param   buf   Buffer with the marshalled data
+ * @return        The number of unmarshalled bytes, 0 on error
+ */
+size_t
+ring_unmarshal(struct ring *restrict this, const void *restrict buf)
+{
+	size_t off = 0;
+	const char *bs = buf;
+
+	ring_initialise(this);
+
+	this->size = this->end = *(const size_t *)&bs[off];
+	off += sizeof(size_t);
+
+	if (this->end > 0) {
+		this->buffer = malloc(this->end);
+		if (!this->buffer)
+			return 0;
+
+		memcpy(this->buffer, bs + off, this->end);
+		off += this->end;
+	}
+
+	return off;
+}
+
+
+#if defined(__clang__)
+# pragma GCC diagnostic pop
+#endif
+
+
+/**
+ * Append data to a ring buffer
+ * 
+ * @param   this  The ring buffer
+ * @param   data  The new data
+ * @param   n     The number of bytes in `data`
+ * @return        Zero on success, -1 on error
+ */
+int
+ring_push(struct ring *restrict this, void *restrict data, size_t n)
+{
+	size_t used = 0;
+	char *restrict new;
+
+	if (this->start == this->end) {
+		if (this->buffer)
+			used = this->size;
+	} else if (this->start > this->end) {
+		used = this->size - this->start + this->end;
+	} else {
+		used = this->start - this->end;
+	}
+
+	if (used + n > this->size) {
+		new = malloc(used + n);
+		if (!new)
+			return -1;
+		if (this->buffer) {
+			if (this->start < this->end) {
+				memcpy(new, this->buffer + this->start, this->end - this->start);
+			} else {
+				memcpy(new, this->buffer + this->start, this->size - this->start);
+				memcpy(new + this->size - this->start, this->buffer, this->end);
+			}
+		}
+		memcpy(new + used, data, n);
+		this->buffer = new;
+		this->start = 0;
+		this->end = used + n;
+		this->size = used + n;
+	} else if (this->start >= this->end || this->end + n <= this->size) {
+		memcpy(&this->buffer[this->end], data, n);
+		this->end += n;
+	} else {
+		memcpy(&this->buffer[this->end], data, this->size - this->end);
+		data = &((char *)data)[this->size - this->end];
+		n -= this->size - this->end;
+		memcpy(this->buffer, data, n);
+		this->end = n;
+	}
+
+	return 0;
+}
+
+
+/**
+ * Get queued data from a ring buffer
+ * 
+ * It can take up to two calls (with `ring_pop` between)
+ * to get all queued data
+ * 
+ * @param   this  The ring buffer
+ * @param   n     Output parameter for the length
+ *                of the returned segment
+ * @return        The beginning of the queued data,
+ *                `NULL` if there is nothing more
+ */
+void *
+ring_peek(struct ring *restrict this, size_t *restrict n)
+{
+	if (!this->buffer) {
+		*n = 0;
+		return NULL;
+	}
+
+	if (this->start < this->end)
+		*n = this->end - this->start;
+	else
+		*n = this->size - this->start;
+	return this->buffer + this->start;
+}
+
+
+/**
+ * Dequeue data from a ring bubber
+ * 
+ * @param  this  The ring buffer
+ * @param  n     The number of bytes to dequeue
+ */
+void
+ring_pop(struct ring *restrict this, size_t n)
+{
+	this->start += n;
+	this->start %= this->size;
+	if (this->start == this->end) {
+		free(this->buffer);
+		this->start  = 0;
+		this->end    = 0;
+		this->size   = 0;
+		this->buffer = NULL;
+	}
+}
-- 
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