shared: add helpers for unaligend BE read/write

1 files changed, 56 insertions, 0 deletions

diff --git a/src/shared/unaligned.h b/src/shared/unaligned.h
new file mode 100644
index 0000000000..b194d71017
--- /dev/null
+++ b/src/shared/unaligned.h
@@ -0,0 +1,56 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Tom Gundersen
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdint.h>
+
+#include "sparse-endian.h"
+
+static inline uint16_t unaligned_read_be16(const be16_t *u) {
+        return (((uint16_t) ((uint8_t*) u)[0]) << 8) |
+                ((uint16_t) ((uint8_t*) u)[1]);
+}
+
+static inline uint32_t unaligned_read_be32(const be32_t *u) {
+        return (((uint32_t) unaligned_read_be16((be16_t*) u)) << 16) |
+                ((uint32_t) unaligned_read_be16((be16_t*) u + 1));
+}
+
+static inline uint64_t unaligned_read_be64(const be64_t *u) {
+        return (((uint64_t) unaligned_read_be32((be32_t*) u)) << 32) |
+                ((uint64_t) unaligned_read_be32((be32_t*) u + 1));
+}
+
+static inline void unaligned_write_be16(be16_t *u, uint16_t a) {
+        ((uint8_t*) u)[0] = (uint8_t) (a >> 8);
+        ((uint8_t*) u)[1] = (uint8_t) a;
+}
+
+static inline void unaligned_write_be32(be32_t *u, uint32_t a) {
+        unaligned_write_be16((be16_t*) u, (uint16_t) (a >> 16));
+        unaligned_write_be16((be16_t*) u + 1, (uint16_t) a);
+}
+
+static inline void unaligned_write_be64(be64_t *u, uint64_t a) {
+        unaligned_write_be32((be32_t*) u, (uint32_t) (a >> 32));
+        unaligned_write_be32((be32_t*) u + 1, (uint32_t) a);
+}