From dbbdf3f6644ee61a74e364727a630117eb6e20cf Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Thu, 11 Jan 2018 23:47:22 +0100
Subject: [PATCH] sys: introduce iolist
---
sys/include/iolist.h | 87 ++++++++++++++++++++++++++++++++++++++++++++
sys/iolist/Makefile | 1 +
sys/iolist/iolist.c | 61 +++++++++++++++++++++++++++++++
3 files changed, 149 insertions(+)
create mode 100644 sys/include/iolist.h
create mode 100644 sys/iolist/Makefile
create mode 100644 sys/iolist/iolist.c
diff --git a/sys/include/iolist.h b/sys/include/iolist.h
new file mode 100644
index 0000000000..e5d8d753e7
--- /dev/null
+++ b/sys/include/iolist.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2018 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup sys_util_iolist iolist scatter / gather IO
+ * @ingroup sys_util
+ * @brief Provides linked-list scatter / gather IO
+ *
+ * @{
+ *
+ * @file
+ * @brief iolist scatter / gather IO
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ */
+
+#ifndef IOLIST_H
+#define IOLIST_H
+
+#include <unistd.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief iolist forward declaration */
+typedef struct iolist iolist_t;
+
+/**
+ * @brief iolist structure definition
+ */
+struct iolist {
+ iolist_t *iol_next; /**< ptr to next list entry */
+ void *iol_base; /**< ptr to this list entries data */
+ size_t iol_len; /**< size of data pointet to by ptr */
+};
+
+/**
+ * @brief Count number of entries in an iolist_t
+ *
+ * @param[in] iolist iolist to count
+ *
+ * @returns number of entries (zero for NULL parameter)
+ */
+unsigned iolist_count(const iolist_t *iolist);
+
+/**
+ * @brief Sum up number of bytes in iolist
+ *
+ * This function returns the summed ip lenght values of all entries in @p
+ * iolist.
+ *
+ * @param[in] iolist iolist to sum up
+ *
+ * @returns summed up number of bytes or zero if @p iolist == NULL
+ */
+size_t iolist_size(const iolist_t *iolist);
+
+/** @brief struct iovec anonymous declaration */
+struct iovec;
+
+/**
+ * @brief Create struct iovec from iolist
+ *
+ * This function fills an array of struct iovecs with the contents of @p
+ * iolist. It will write the number of used array entries into @p count.
+ *
+ * The caller *must* ensure that @p iov p points to an array of size >= count!
+ *
+ * @param[in] iolist iolist to read from
+ * @param[out] iov ptr to array of struct iovec that will be filled
+ * @param[out] count number of elements in @p iolist
+ *
+ * @returns iolist_size(iolist)
+ */
+size_t iolist_to_iovec(const iolist_t *iolist, struct iovec *iov, unsigned *count);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* IOLIST_H */
+/** @} */
diff --git a/sys/iolist/Makefile b/sys/iolist/Makefile
new file mode 100644
index 0000000000..48422e909a
--- /dev/null
+++ b/sys/iolist/Makefile
@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base
diff --git a/sys/iolist/iolist.c b/sys/iolist/iolist.c
new file mode 100644
index 0000000000..b64f0139e2
--- /dev/null
+++ b/sys/iolist/iolist.c
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2018 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup sys_util
+ * @{
+ *
+ * @file
+ * @brief iolist scatter / gather IO
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ * @}
+ */
+
+#include <sys/uio.h>
+
+#include "iolist.h"
+
+unsigned iolist_count(const iolist_t *iolist)
+{
+ unsigned count = 0;
+ while (iolist) {
+ count++;
+ iolist = iolist->iol_next;
+ }
+ return count;
+}
+
+size_t iolist_size(const iolist_t *iolist)
+{
+ size_t result = 0;
+ while (iolist) {
+ result += iolist->iol_len;
+ iolist = iolist->iol_next;
+ }
+ return result;
+}
+
+size_t iolist_to_iovec(const iolist_t *iolist, struct iovec *iov, unsigned *count)
+{
+ size_t bytes = 0;
+ unsigned _count = 0;
+
+ while (iolist) {
+ iov->iov_base = iolist->iol_base;
+ iov->iov_len = iolist->iol_len;
+ bytes += iov->iov_len;
+ _count++;
+ iolist = iolist->iol_next;
+ iov++;
+ }
+
+ *count = _count;
+
+ return bytes;
+}
--
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