1 files changed, 81 insertions, 0 deletions
diff --git a/packet.h b/packet.h
new file mode 100644
index 0000000..0ef8849
--- /dev/null
+++ b/packet.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: AGPL-3.0-or-later
+ * Copyright (c) 2022 Red Hat GmbH
+ * Author: Stefano Brivio <sbrivio@redhat.com>
+ */
+
+#ifndef PACKET_H
+#define PACKET_H
+
+/**
+ * struct desc - Generic offset-based descriptor within buffer
+ * @offset:	Offset of descriptor relative to buffer start, 32-bit limit
+ * @len:	Length of descriptor, host order, 16-bit limit
+ */
+struct desc {
+	uint32_t offset;
+	uint16_t len;
+};
+
+/**
+ * struct pool - Generic pool of packets stored in a buffer
+ * @buf:	Buffer storing packet descriptors
+ * @buf_size:	Total size of buffer
+ * @size:	Number of usable descriptors for the pool
+ * @count:	Number of used descriptors for the pool
+ * @pkt:	Descriptors: see macros below
+ */
+struct pool {
+	char *buf;
+	size_t buf_size;
+	size_t size;
+	size_t count;
+	struct desc pkt[1];
+};
+
+void packet_add_do(struct pool *p, size_t len, const char *start,
+		   const char *func, const int line);
+void *packet_get_do(struct pool *p, size_t index, size_t offset, size_t len,
+		    size_t *left, const char *func, const int line);
+void pool_flush(struct pool *p);
+
+#define packet_add(p, len, start)					\
+	packet_add_do(p, len, start, __func__, __LINE__);
+
+#define packet_get(p, index, offset, len, left)				\
+	packet_get_do(p, index, offset, len, left, __func__, __LINE__);
+
+#define packet_get_try(p, index, offset, len, left)			\
+	packet_get_do(p, index, offset, len, left, NULL, 0)
+
+#define PACKET_POOL_DECL(_name, _size, _buf)				\
+struct _name ## _t {							\
+	char *buf;							\
+	size_t buf_size;						\
+	size_t size;							\
+	size_t count;							\
+	struct desc pkt[_size];						\
+}
+
+#define PACKET_POOL_INIT_NOCAST(_size, _buf, _buf_size)			\
+{									\
+	.buf_size = _buf_size,						\
+	.buf = _buf,							\
+	.size = _size,							\
+}
+
+#define PACKET_POOL(name, size, buf, buf_size)				\
+	PACKET_POOL_DECL(name, size, buf) name = 			\
+		PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
+
+#define PACKET_INIT(name, size, buf, buf_size)				\
+	(struct name ## _t) PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
+
+#define PACKET_POOL_NOINIT(name, size, buf)				\
+	PACKET_POOL_DECL(name, size, buf) name ## _storage;		\
+	static struct pool *name = (struct pool *)&name ## _storage
+
+#define PACKET_POOL_P(name, size, buf, buf_size)			\
+	PACKET_POOL(name ## _storage, size, buf, buf_size);		\
+	struct pool *name = (struct pool *)&name ## _storage
+
+#endif /* PACKET_H */