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/* 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
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