mirror of
https://github.com/DrBeef/JKXR.git
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4597b03873
Opens in Android Studio but haven't even tried to build it yet (it won't.. I know that much!)
86 lines
3.3 KiB
C++
86 lines
3.3 KiB
C++
/*
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===========================================================================
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Copyright (C) 1999 - 2005, Id Software, Inc.
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Copyright (C) 2000 - 2013, Raven Software, Inc.
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Copyright (C) 2001 - 2013, Activision, Inc.
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Copyright (C) 2013 - 2015, OpenJK contributors
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This file is part of the OpenJK source code.
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OpenJK is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License version 2 as
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published by the Free Software Foundation.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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===========================================================================
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*/
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// vmachine.cpp -- wrapper to fake virtual machine for client
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#include "vmachine.h"
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/*
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==============================================================
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VIRTUAL MACHINE
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==============================================================
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*/
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intptr_t VM_Call( int callnum, ... )
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{
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intptr_t args[10] = { 0 };
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va_list ap;
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if ( cgvm.entryPoint ) {
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va_start( ap, callnum );
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for ( size_t i = 0; i < ARRAY_LEN( args ); i++ )
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args[i] = va_arg( ap, intptr_t );
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va_end(ap);
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return cgvm.entryPoint( callnum, args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7],
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args[8], args[9]);
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}
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return -1;
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}
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// The syscall mechanism relies on stack manipulation to get it's args.
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// This is likely due to C's inability to pass "..." parameters to a function in one clean chunk.
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// On PowerPC Linux, these parameters are not necessarily passed on the stack, so while (&arg[0] == arg) is true,
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// (&arg[1] == 2nd function parameter) is not necessarily accurate, as arg's value might have been stored to the stack
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// or other piece of scratch memory to give it a valid address, but the next parameter might still be sitting in a
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// register.
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// QVM's syscall system also assumes that the stack grows downward, and that any needed types can be squeezed, safely,
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// into a signed int.
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// This hack below copies all needed values for an argument to an array in memory, so that QVM can get the correct values.
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// This can also be used on systems where the stack grows upwards, as the presumably standard and safe stdargs.h macros
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// are used.
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// The original code, while probably still inherently dangerous, seems to work well enough for the platforms it already
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// works on. Rather than add the performance hit for those platforms, the original code is still in use there.
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// For speed, we just grab 9 arguments, and don't worry about exactly how many the syscall actually needs; the extra is
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// thrown away.
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extern intptr_t CL_CgameSystemCalls( intptr_t *args );
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intptr_t VM_DllSyscall( intptr_t arg, ... ) {
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#if !id386 || defined __clang__ || defined MACOS_X
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// rcg010206 - see commentary above
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intptr_t args[16];
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va_list ap;
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args[0] = arg;
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va_start( ap, arg );
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for (size_t i = 1; i < ARRAY_LEN (args); i++)
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args[i] = va_arg( ap, intptr_t );
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va_end( ap );
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return CL_CgameSystemCalls( args );
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#else // original id code
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return CL_CgameSystemCalls( &arg );
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#endif
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}
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