endian.c/h -> endianconv.c/h to avoid issues with broken libraries search paths.

[redis.git] / src / endianconv.c

diff --git a/src/endianconv.c b/src/endianconv.c
new file mode 100644 (file)
index 0000000..9adf09c
--- /dev/null
+++ b/src/endianconv.c
@@ -0,0 +1,124 @@
+/* endinconv.c -- Endian conversions utilities.
+ *
+ * This functions are never called directly, but always using the macros
+ * defined into endianconv.h, this way we define everything is a non-operation
+ * if the arch is already little endian.
+ *
+ * Redis tries to encode everything as little endian (but a few things that need
+ * to be backward compatible are still in big endian) because most of the
+ * production environments are little endian, and we have a lot of conversions
+ * in a few places because ziplists, intsets, zipmaps, need to be endian-neutral
+ * even in memory, since they are serialied on RDB files directly with a single
+ * write(2) without other additional steps.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2011-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include <stdint.h>
+
+/* Toggle the 16 bit unsigned integer pointed by *p from little endian to
+ * big endian */
+void memrev16(void *p) {
+    unsigned char *x = p, t;
+
+    t = x[0];
+    x[0] = x[1];
+    x[1] = t;
+}
+
+/* Toggle the 32 bit unsigned integer pointed by *p from little endian to
+ * big endian */
+void memrev32(void *p) {
+    unsigned char *x = p, t;
+
+    t = x[0];
+    x[0] = x[3];
+    x[3] = t;
+    t = x[1];
+    x[1] = x[2];
+    x[2] = t;
+}
+
+/* Toggle the 64 bit unsigned integer pointed by *p from little endian to
+ * big endian */
+void memrev64(void *p) {
+    unsigned char *x = p, t;
+
+    t = x[0];
+    x[0] = x[7];
+    x[7] = t;
+    t = x[1];
+    x[1] = x[6];
+    x[6] = t;
+    t = x[2];
+    x[2] = x[5];
+    x[5] = t;
+    t = x[3];
+    x[3] = x[4];
+    x[4] = t;
+}
+
+uint16_t intrev16(uint16_t v) {
+    memrev16(&v);
+    return v;
+}
+
+uint32_t intrev32(uint32_t v) {
+    memrev32(&v);
+    return v;
+}
+
+uint64_t intrev64(uint64_t v) {
+    memrev64(&v);
+    return v;
+}
+
+#ifdef TESTMAIN
+#include <stdio.h>
+
+int main(void) {
+    char buf[32];
+
+    sprintf(buf,"ciaoroma");
+    memrev16(buf);
+    printf("%s\n", buf);
+
+    sprintf(buf,"ciaoroma");
+    memrev32(buf);
+    printf("%s\n", buf);
+
+    sprintf(buf,"ciaoroma");
+    memrev64(buf);
+    printf("%s\n", buf);
+
+    return 0;
+}
+#endif