shared: add helpers for unaligend BE read/write

2 files changed, 148 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);
+}
diff --git a/src/test/test-unaligned.c b/src/test/test-unaligned.c
new file mode 100644
index 0000000000..52693cd325
--- /dev/null
+++ b/src/test/test-unaligned.c
@@ -0,0 +1,92 @@
+/***
+  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 "unaligned.h"
+#include "util.h"
+
+static uint8_t data[] = {
+        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+        0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+};
+
+int main(int argc, const char *argv[]) {
+        uint8_t scratch[16];
+
+        assert_se(unaligned_read_be16((be16_t*)&data[0]) == 0x0001);
+        assert_se(unaligned_read_be16((be16_t*)&data[1]) == 0x0102);
+
+        assert_se(unaligned_read_be32((be32_t*)&data[0]) == 0x00010203);
+        assert_se(unaligned_read_be32((be32_t*)&data[1]) == 0x01020304);
+        assert_se(unaligned_read_be32((be32_t*)&data[2]) == 0x02030405);
+        assert_se(unaligned_read_be32((be32_t*)&data[3]) == 0x03040506);
+
+        assert_se(unaligned_read_be64((be64_t*)&data[0]) == 0x0001020304050607);
+        assert_se(unaligned_read_be64((be64_t*)&data[1]) == 0x0102030405060708);
+        assert_se(unaligned_read_be64((be64_t*)&data[2]) == 0x0203040506070809);
+        assert_se(unaligned_read_be64((be64_t*)&data[3]) == 0x030405060708090a);
+        assert_se(unaligned_read_be64((be64_t*)&data[4]) == 0x0405060708090a0b);
+        assert_se(unaligned_read_be64((be64_t*)&data[5]) == 0x05060708090a0b0c);
+        assert_se(unaligned_read_be64((be64_t*)&data[6]) == 0x060708090a0b0c0d);
+        assert_se(unaligned_read_be64((be64_t*)&data[7]) == 0x0708090a0b0c0d0e);
+
+        zero(scratch);
+        unaligned_write_be16((uint16_t*)&scratch[0], 0x0001);
+        assert_se(memcmp(&scratch[0], &data[0], sizeof(uint16_t)) == 0);
+        zero(scratch);
+        unaligned_write_be16((uint16_t*)&scratch[1], 0x0102);
+        assert_se(memcmp(&scratch[1], &data[1], sizeof(uint16_t)) == 0);
+
+        zero(scratch);
+        unaligned_write_be32((be32_t*)&scratch[0], 0x00010203);
+        assert_se(memcmp(&scratch[0], &data[0], sizeof(uint32_t)) == 0);
+        zero(scratch);
+        unaligned_write_be32((be32_t*)&scratch[1], 0x01020304);
+        assert_se(memcmp(&scratch[1], &data[1], sizeof(uint32_t)) == 0);
+        zero(scratch);
+        unaligned_write_be32((be32_t*)&scratch[2], 0x02030405);
+        assert_se(memcmp(&scratch[2], &data[2], sizeof(uint32_t)) == 0);
+        zero(scratch);
+        unaligned_write_be32((be32_t*)&scratch[3], 0x03040506);
+        assert_se(memcmp(&scratch[3], &data[3], sizeof(uint32_t)) == 0);
+
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[0], 0x0001020304050607);
+        assert_se(memcmp(&scratch[0], &data[0], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[1], 0x0102030405060708);
+        assert_se(memcmp(&scratch[1], &data[1], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[2], 0x0203040506070809);
+        assert_se(memcmp(&scratch[2], &data[2], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[3], 0x030405060708090a);
+        assert_se(memcmp(&scratch[3], &data[3], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[4], 0x0405060708090a0b);
+        assert_se(memcmp(&scratch[4], &data[4], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[5], 0x05060708090a0b0c);
+        assert_se(memcmp(&scratch[5], &data[5], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[6], 0x060708090a0b0c0d);
+        assert_se(memcmp(&scratch[6], &data[6], sizeof(uint64_t)) == 0);
+        zero(scratch);
+        unaligned_write_be64((be64_t*)&scratch[7], 0x0708090a0b0c0d0e);
+        assert_se(memcmp(&scratch[7], &data[7], sizeof(uint64_t)) == 0);
+}