diff options
Diffstat (limited to 'src/VBox/Runtime/common/checksum/adler32.cpp')
| -rw-r--r-- | src/VBox/Runtime/common/checksum/adler32.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/checksum/adler32.cpp b/src/VBox/Runtime/common/checksum/adler32.cpp new file mode 100644 index 00000000..2908e17f --- /dev/null +++ b/src/VBox/Runtime/common/checksum/adler32.cpp @@ -0,0 +1,171 @@ +/* $Id: adler32.cpp $ */ +/** @file + * IPRT - Adler-32 + */ + +/* + * Copyright (C) 2009-2019 Oracle Corporation + * + * This file is part of VirtualBox Open Source Edition (OSE), as + * available from http://www.virtualbox.org. This file is free software; + * you can redistribute it and/or modify it under the terms of the GNU + * General Public License (GPL) as published by the Free Software + * Foundation, in version 2 as it comes in the "COPYING" file of the + * VirtualBox OSE distribution. VirtualBox OSE is distributed in the + * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. + * + * The contents of this file may alternatively be used under the terms + * of the Common Development and Distribution License Version 1.0 + * (CDDL) only, as it comes in the "COPYING.CDDL" file of the + * VirtualBox OSE distribution, in which case the provisions of the + * CDDL are applicable instead of those of the GPL. + * + * You may elect to license modified versions of this file under the + * terms and conditions of either the GPL or the CDDL or both. + */ + + +/********************************************************************************************************************************* +* Header Files * +*********************************************************************************************************************************/ +#include <iprt/crc.h> +#include "internal/iprt.h" + +#include <iprt/asm.h> +#include <iprt/assert.h> + + +/********************************************************************************************************************************* +* Defined Constants And Macros * +*********************************************************************************************************************************/ +#define RTCRC_ADLER_32_NUMBER 65521 + + +RTDECL(uint32_t) RTCrcAdler32(void const *pv, size_t cb) +{ + /* Don't want to do the unrolling twice. */ + return RTCrcAdler32Process(RTCrcAdler32Start(), pv, cb); +} + + +RTDECL(uint32_t) RTCrcAdler32Start(void) +{ + return 1; +} + + +RTDECL(uint32_t) RTCrcAdler32Process(uint32_t u32Crc, void const *pv, size_t cb) +{ + uint8_t const *pbSrc = (uint8_t const *)pv; + uint32_t a = u32Crc & 0xffff; + uint32_t b = u32Crc >> 16; + if (cb < 64 /* randomly selected number */) + { + while (cb-- > 0) + { + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + } + } + else + { + switch (((uintptr_t)pbSrc & 0x3)) + { + case 0: + break; + + case 1: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + RT_FALL_THRU(); + + case 2: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + RT_FALL_THRU(); + + case 3: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + break; + } + + while (cb >= 4) + { + uint32_t u32 = *(uint32_t const *)pbSrc; + pbSrc += 4; + + a += u32 & 0xff; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + + a += (u32 >> 8) & 0xff; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + + a += (u32 >> 16) & 0xff; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + + a += (u32 >> 24) & 0xff; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + + cb -= 4; + } + + switch (cb) + { + case 0: + break; + + case 3: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + RT_FALL_THRU(); + + case 2: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + RT_FALL_THRU(); + + case 1: + a += *pbSrc++; + a %= RTCRC_ADLER_32_NUMBER; + b += a; + b %= RTCRC_ADLER_32_NUMBER; + cb--; + break; + } + } + + return a | (b << 16); +} + + +RTDECL(uint32_t) RTCrcAdler32Finish(uint32_t u32Crc) +{ + return u32Crc; +} + |