Source code of Windows XP (NT5)
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/*****************************************************************************
*
* DIGuid.c
*
* Copyright (c) 1996 Microsoft Corporation. All Rights Reserved.
*
* Abstract:
*
* Misc GUID-related helper functions.
*
* Contents:
*
* DICreateGuid
*
*****************************************************************************/
#include "dinputpr.h"
/*****************************************************************************
*
* The sqiffle for this file.
*
*****************************************************************************/
#define sqfl sqflUtil
/*****************************************************************************
*
* Globals
*
*****************************************************************************/
typedef void (__stdcall *UUIDCREATE)(OUT LPGUID pguid);
UUIDCREATE g_UuidCreate;
/*****************************************************************************
*
* @doc INTERNAL
*
* @func void | FakeUuidCreate |
*
* Create a GUID using a fake algorithm that is close enough.
* Since we don't let our GUIDs leave the DirectInput world,
* the uniqueness policy can be relaxed.
*
* OLE generates a GUID as follows:
*
* Get the current local time in FILETIME format.
*
* Add the magic number 0x00146bf33e42c000 = 580819200 seconds =
* 9580320 minutes = 159672 hours = 6653 days, approximately
* 18 years. Who knows why.
*
* Subtract 0x00989680 (approximately 256 seconds). Who
* knows why.
*
* If you combine the above two steps, the net result is to
* add 0x00146bf33daa2980.
*
* The dwLowDateTime of the resulting FILETIME becomes Data1.
*
* The dwHighDateTime of the resulting FILETIME becomes
* Data2 and Data3, except that the high nibble of Data3
* is forced to 1.
*
* The first two bytes of Data4 are a big-endian 10-bit
* sequence counter, with the top bit set and the other
* bits zero.
*
* The last six bytes are the network card identifier.
*
* @parm LPGUID | pguid |
*
* Receives the GUID to create.
*
*****************************************************************************/
void INTERNAL
FakeUuidCreate(LPGUID pguid)
{
LONG lRc;
SYSTEMTIME st;
union {
FILETIME ft;
DWORDLONG ldw;
} u;
GetLocalTime(&st);
SystemTimeToFileTime(&st, &u.ft);
u.ldw += 0x00146BF33DAA2980;
/*
* Note: The wacky pun is actually safe on a RISC because
* Data2 is already dword-aligned.
*/
pguid->Data1 = u.ft.dwLowDateTime;
*(LPDWORD)&pguid->Data2 = (u.ft.dwHighDateTime & 0x0FFFFFFF) | 0x10000000;
lRc = Excl_UniqueGuidInteger();
lRc = lRc & 0x3FFF;
pguid->Data4[0] = 0x80 | HIBYTE(lRc);
pguid->Data4[1] = LOBYTE(lRc);
/*
* We use the network adapter ID of the dial-up adapter as our
* network ID. No real network adapter will have this ID.
*/
pguid->Data4[2] = 'D';
pguid->Data4[3] = 'E';
pguid->Data4[4] = 'S';
pguid->Data4[5] = 'T';
pguid->Data4[6] = 0x00;
pguid->Data4[7] = 0x00;
}
/*****************************************************************************
*
* @doc INTERNAL
*
* @func void | DICreateGuid |
*
* Create a GUID. Because we don't want to pull in all of OLE,
* we don't actually use RPCRT4
*
* @parm LPGUID | pguid |
*
* Receives the GUID to create.
*
*****************************************************************************/
void EXTERNAL
DICreateGuid(LPGUID pguid)
{
AssertF(g_hmtxGlobal);
FakeUuidCreate(pguid);
}
/*****************************************************************************
*
* @doc INTERNAL
*
* @func void | DICreateStaticGuid |
*
* Create a "static" <t GUID>, which is a <t GUID> that can be
* deterministically regenerated from its parameters.
*
* This is used to invent <t GUID>s for HID devices
* and vendors.
*
* The entire <t GUID> is zero, except for the pid and vid
* which go into Data1, and the network adapter
* ID is the dial-up adapter.
*
* We put the variable bits into the Data1 because that's
* how GUIDs work.
*
* The resulting GUID is {pidvid-0000-0000-0000-504944564944}
*
* @parm LPGUID | pguid |
*
* Receives the created <t GUID>.
*
*****************************************************************************/
void EXTERNAL
DICreateStaticGuid(LPGUID pguid, WORD pid, WORD vid)
{
pguid->Data1 = MAKELONG(vid, pid);
pguid->Data2 = 0;
pguid->Data3 = 0;
/*
* We use the string "PIDVID" as our network adapter ID.
* No real network adapter will have this ID.
*/
pguid->Data4[0] = 0x00;
pguid->Data4[1] = 0x00;
pguid->Data4[2] = 'P';
pguid->Data4[3] = 'I';
pguid->Data4[4] = 'D';
pguid->Data4[5] = 'V';
pguid->Data4[6] = 'I';
pguid->Data4[7] = 'D';
}