135 lines
3.4 KiB
C++
135 lines
3.4 KiB
C++
// STRTOHEX.CPP
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//
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// Utility functions to convert string representations of hexadecimal numbers
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// into the numbers themselves.
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//
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// Note: These functions are in their own file, rather than in STRUTIL.CPP,
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// because they use a const array. The current implementation of the linker
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// pulls this array into binaries if they use any function in the source file,
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// not just the functions which reference this array.
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#include "precomp.h"
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#include <strutil.h>
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// This array maps ASCII chars in the range '0' - 'f' to their hex equivalent.
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// INVALID_CHAR_ID is used to mark slots that don't correspond to a valid
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// hex char.
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const BYTE INVALID_CHAR_ID = (BYTE) -1;
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const BYTE rgbHexCharMap[] =
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{
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// ASCII 0x30 - 0x3f
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0, 1, 2, 3,
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4, 5, 6, 7,
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8, 9, INVALID_CHAR_ID, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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// ASCII 0x40 - 0x4f
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INVALID_CHAR_ID, 0xA, 0xB, 0xC,
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0xD, 0xE, 0xF, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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// ASCII 0x50 - 0x5f
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID, INVALID_CHAR_ID,
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// ASCII 0x60 - 0x67
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INVALID_CHAR_ID, 0xa, 0xb, 0xc,
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0xd, 0xe, 0xf, INVALID_CHAR_ID
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};
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const int cbHexCharMap = ARRAY_ELEMENTS(rgbHexCharMap);
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//
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// HexStringToQWordA()
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//
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// Converts a hex ANSI string (without 0x or 0X prefix) to a ULARGE_INTEGER
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//
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// NOTE: The a-f characters can be lowercase or uppercase
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//
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// Returns TRUE if successful (the string contained all valid characters)
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// Returns FALSE otherwise
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//
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BOOL NMINTERNAL HexStringToQWordA(LPCSTR pcszString, ULARGE_INTEGER* pqw)
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{
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BOOL bRet;
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ASSERT(pcszString);
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ASSERT(pqw);
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pqw->QuadPart = 0ui64;
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int cchStr = lstrlenA(pcszString);
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if (cchStr <= CCH_HEX_QWORD)
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{
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bRet = TRUE;
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PDWORD pdwCur = (cchStr < CCH_HEX_DWORD) ? &(pqw->LowPart) : &(pqw->HighPart);
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for (int i = 0; i < cchStr; i++)
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{
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// NOTE: DBCS characters are not allowed
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ASSERT(! IsDBCSLeadByte(pcszString[i]));
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if (CCH_HEX_DWORD == (cchStr - i))
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{
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pdwCur = &(pqw->LowPart);
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}
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DWORD dwDigit = (DWORD) INVALID_CHAR_ID;
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int iDigit = pcszString[i] - '0';
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if (iDigit >= 0 && iDigit < cbHexCharMap)
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{
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dwDigit = (DWORD) rgbHexCharMap[iDigit];
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}
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if (INVALID_CHAR_ID != dwDigit)
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{
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*pdwCur = ((*pdwCur) << BITS_PER_HEX_CHAR) + dwDigit;
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}
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else
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{
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bRet = FALSE;
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break;
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}
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}
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}
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else
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{
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bRet = FALSE;
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}
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return bRet;
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}
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/* D W F R O M H E X */
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/*-------------------------------------------------------------------------
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%%Function: DwFromHex
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Return the DWORD from the hex string.
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-------------------------------------------------------------------------*/
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DWORD DwFromHex(LPCTSTR pchHex)
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{
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TCHAR ch;
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DWORD dw = 0;
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while (_T('\0') != (ch = *pchHex++))
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{
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DWORD dwDigit = (DWORD) INVALID_CHAR_ID;
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int iDigit = ch - _T('0');
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if (iDigit >= 0 && iDigit < cbHexCharMap)
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{
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dwDigit = (DWORD) rgbHexCharMap[iDigit];
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}
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if (INVALID_CHAR_ID != dwDigit)
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{
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dw = (dw << 4) + dwDigit;
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}
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else
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break;
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}
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return dw;
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}
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