109 lines
2.4 KiB
C
109 lines
2.4 KiB
C
/* endinconv.c -- Endian conversions utilities.
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*
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* This functions are never called directly, but always using the macros
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* defined into endianconv.h, this way we define everything is a non-operation
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* if the arch is already little endian.
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*
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* Redis tries to encode everything as little endian (but a few things that need
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* to be backward compatible are still in big endian) because most of the
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* production environments are little endian, and we have a lot of conversions
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* in a few places because ziplists, intsets, zipmaps, need to be endian-neutral
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* even in memory, since they are serialized on RDB files directly with a single
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* write(2) without other additional steps.
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*
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* ----------------------------------------------------------------------------
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*
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* Copyright (c) 2011-Present, Redis Ltd.
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* All rights reserved.
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*
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* Licensed under your choice of the Redis Source Available License 2.0
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* (RSALv2) or the Server Side Public License v1 (SSPLv1).
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*/
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#include <stdint.h>
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/* Toggle the 16 bit unsigned integer pointed by *p from little endian to
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* big endian */
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void memrev16(void *p) {
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unsigned char *x = p, t;
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t = x[0];
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x[0] = x[1];
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x[1] = t;
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}
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/* Toggle the 32 bit unsigned integer pointed by *p from little endian to
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* big endian */
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void memrev32(void *p) {
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unsigned char *x = p, t;
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t = x[0];
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x[0] = x[3];
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x[3] = t;
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t = x[1];
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x[1] = x[2];
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x[2] = t;
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}
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/* Toggle the 64 bit unsigned integer pointed by *p from little endian to
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* big endian */
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void memrev64(void *p) {
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unsigned char *x = p, t;
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t = x[0];
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x[0] = x[7];
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x[7] = t;
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t = x[1];
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x[1] = x[6];
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x[6] = t;
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t = x[2];
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x[2] = x[5];
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x[5] = t;
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t = x[3];
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x[3] = x[4];
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x[4] = t;
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}
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uint16_t intrev16(uint16_t v) {
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memrev16(&v);
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return v;
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}
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uint32_t intrev32(uint32_t v) {
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memrev32(&v);
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return v;
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}
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uint64_t intrev64(uint64_t v) {
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memrev64(&v);
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return v;
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}
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#ifdef REDIS_TEST
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#include <stdio.h>
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#define UNUSED(x) (void)(x)
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int endianconvTest(int argc, char *argv[], int flags) {
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char buf[32];
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UNUSED(argc);
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UNUSED(argv);
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UNUSED(flags);
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snprintf(buf,sizeof(buf),"ciaoroma");
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memrev16(buf);
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printf("%s\n", buf);
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snprintf(buf,sizeof(buf),"ciaoroma");
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memrev32(buf);
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printf("%s\n", buf);
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snprintf(buf,sizeof(buf),"ciaoroma");
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memrev64(buf);
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printf("%s\n", buf);
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return 0;
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}
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#endif
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