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95 lines
2.3 KiB
C
95 lines
2.3 KiB
C
/** @file
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OcRtcLib - library with RTC I/O functions
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Copyright (c) 2017-2018, vit9696
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All rights reserved.
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#ifndef OC_RTC_LIB_H
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#define OC_RTC_LIB_H
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#include <Protocol/AppleRtcRam.h>
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//
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// Standard interface, available on most Intel chipsets
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//
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UINT8
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OcRtcRead (
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IN UINT8 Offset
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);
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VOID
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OcRtcWrite (
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IN UINT8 Offset,
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IN UINT8 Value
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);
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/**
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Calculate Apple CMOS checksum.
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This is a modified version of ANSI CRC16 in REFIN mode (0xA001 poly).
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See http://zlib.net/crc_v3.txt for more details.
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1. Effective poly is 0x2001 due to a bitwise OR with BIT15.
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The change turns CRC16 into CRC14, making BIT14 and BIT15 always zero.
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This modification is commonly found in legacy Phoenix firmwares,
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where it was used for password hashing as found by dogbert:
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http://sites.google.com/site/dogber1/blag/pwgen-5dec.py
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2. Only 7 shifts per byte are performed instead of the usual 8.
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This might improve checksum quality against specific data, but the exact
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reasons are unknown. The algorithm did not change since its introduction
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in 10.4.x, and since Apple Developer Transition Kit was based on Phoenix
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firmware, this could just be a quick change to get a different checksum.
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@param[in] Data Pointer to data to calculate the checksum of.
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@param[in] Size Size of data.
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@retval Resulting checksum.
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**/
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UINT16
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OcRtcChecksumApple (
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IN CONST VOID *Data,
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IN UINTN Size
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);
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/**
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Install and initialise Apple RTC RAM protocol.
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@param[in] Reinstall Overwrite installed protocol.
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@retval installed or located protocol or NULL.
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**/
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APPLE_RTC_RAM_PROTOCOL *
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OcAppleRtcRamInstallProtocol (
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IN BOOLEAN Reinstall
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);
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//
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// Modern faster interface, available on IvyBridge or newer
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//
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UINT8
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OcRtcReadIvy (
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IN UINT8 Offset
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);
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VOID
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OcRtcWriteIvy (
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IN UINT8 Offset,
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IN UINT8 Value
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);
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#endif // OC_RTC_LIB_H
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