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ntgc.c
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00001 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
00003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00004  *
00005  * The contents of this file are subject to the Mozilla Public License Version
00006  * 1.1 (the "License"); you may not use this file except in compliance with
00007  * the License. You may obtain a copy of the License at
00008  * http://www.mozilla.org/MPL/
00009  *
00010  * Software distributed under the License is distributed on an "AS IS" basis,
00011  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00012  * for the specific language governing rights and limitations under the
00013  * License.
00014  *
00015  * The Original Code is the Netscape Portable Runtime (NSPR).
00016  *
00017  * The Initial Developer of the Original Code is
00018  * Netscape Communications Corporation.
00019  * Portions created by the Initial Developer are Copyright (C) 1998-2000
00020  * the Initial Developer. All Rights Reserved.
00021  *
00022  * Contributor(s):
00023  *
00024  * Alternatively, the contents of this file may be used under the terms of
00025  * either the GNU General Public License Version 2 or later (the "GPL"), or
00026  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00027  * in which case the provisions of the GPL or the LGPL are applicable instead
00028  * of those above. If you wish to allow use of your version of this file only
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00035  *
00036  * ***** END LICENSE BLOCK ***** */
00037 
00038 /*
00039  * GC related routines
00040  *
00041  */
00042 #include <windows.h>
00043 #include "primpl.h"
00044 
00045 PRWord *_MD_HomeGCRegisters(PRThread *t, int isCurrent, int *np) 
00046 {
00047 #if defined(_X86_)
00048     CONTEXT context;
00049     context.ContextFlags = CONTEXT_INTEGER;
00050 
00051     if (_PR_IS_NATIVE_THREAD(t)) {
00052         context.ContextFlags |= CONTEXT_CONTROL;
00053         if (GetThreadContext(t->md.handle, &context)) {
00054             t->md.gcContext[0] = context.Eax;
00055             t->md.gcContext[1] = context.Ebx;
00056             t->md.gcContext[2] = context.Ecx;
00057             t->md.gcContext[3] = context.Edx;
00058             t->md.gcContext[4] = context.Esi;
00059             t->md.gcContext[5] = context.Edi;
00060             t->md.gcContext[6] = context.Esp;
00061             t->md.gcContext[7] = context.Ebp;
00062             *np = PR_NUM_GCREGS;
00063         } else {
00064             PR_ASSERT(0);/* XXX */
00065         }
00066     } else {
00067         /* WARNING WARNING WARNING WARNING WARNING WARNING WARNING
00068          *
00069          * This code is extremely machine dependant and completely 
00070          * undocumented by MS.  Its only known to work experimentally.  
00071          * Ready for a walk on the wild * side?
00072          *
00073          * WARNING WARNING WARNING WARNING WARNING WARNING WARNING */
00074 
00075 #if !defined WIN95 // Win95 does not have fibers
00076         int *fiberData = t->md.fiber_id;
00077 
00078         /* I found these offsets by disassembling SwitchToFiber().
00079          * Are your palms sweating yet?
00080          */
00081 
00082         /* 
00083         ** EAX is on the stack (ESP+0)
00084         ** EDX is on the stack (ESP+4)
00085         ** ECX is on the stack (ESP+8)
00086         */
00087         t->md.gcContext[0] = 0;                /* context.Eax */
00088         t->md.gcContext[1] = fiberData[0x2e];  /* context.Ebx */
00089         t->md.gcContext[2] = 0;                /* context.Ecx */
00090         t->md.gcContext[2] = 0;                /* context.Edx */
00091         t->md.gcContext[4] = fiberData[0x2d];  /* context.Esi */
00092         t->md.gcContext[5] = fiberData[0x2c];  /* context.Edi */
00093         t->md.gcContext[6] = fiberData[0x36];  /* context.Esp */
00094         t->md.gcContext[7] = fiberData[0x32];  /* context.Ebp */
00095         *np = PR_NUM_GCREGS;
00096 #endif
00097     }
00098     return (PRWord *)&t->md.gcContext;
00099 #elif defined(_ALPHA_)
00100 #endif /* defined(_X86_) */
00101 }
00102 
00103 /* This function is not used right now, but is left as a reference.
00104  * If you ever need to get the fiberID from the currently running fiber, 
00105  * this is it.
00106  */
00107 void *
00108 GetMyFiberID()
00109 {
00110 #if defined(_X86_) && !defined(__MINGW32__)
00111     void *fiberData;
00112 
00113     /* A pointer to our tib entry is found at FS:[18]
00114      * At offset 10h is the fiberData pointer.  The context of the 
00115      * fiber is stored in there.  
00116      */
00117     __asm {
00118         mov    EDX, FS:[18h]
00119         mov    EAX, DWORD PTR [EDX+10h]
00120         mov    [fiberData], EAX
00121     }
00122   
00123     return fiberData;
00124 #elif defined(_ALPHA_)
00125 #endif /* defined(_X86_) */
00126 }