- Add MASM assembler files for MSVC x64 projects to support vm_x86 in x64 mode

- Clean up ftol()/snapvector() mess
- Make use of SSE instructions for ftol()/snapvector() if available
- move ftol/snapvector pure assembler to inline assembler, this will add x86_64 and improve support for different calling conventions
- Set FPU control word at program startup to get consistent behaviour on all platforms

code/asm/vm_x86_64.asm

@@ -0,0 +1,76 @@
+; ===========================================================================
+; Copyright (C) 2011 Thilo Schulz <thilo@tjps.eu>
+; 
+; This file is part of Quake III Arena source code.
+; 
+; Quake III Arena source code is free software; you can redistribute it
+; and/or modify it under the terms of the GNU General Public License as
+; published by the Free Software Foundation; either version 2 of the License,
+; or (at your option) any later version.
+; 
+; Quake III Arena source code is distributed in the hope that it will be
+; useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+; GNU General Public License for more details.
+; 
+; You should have received a copy of the GNU General Public License
+; along with Quake III Arena source code; if not, write to the Free Software
+; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+; ===========================================================================
+
+; Call wrapper for vm_x86 when built with MSVC in 64 bit mode,
+; since MSVC does not support inline x64 assembler code anymore.
+;
+; assumes __fastcall calling convention
+
+DoSyscall PROTO
+
+.code
+
+; Call to static void DoSyscall(int syscallNum, int programStack, int *opStackBase, uint8_t opStackOfs, intptr_t arg)
+
+qsyscall64 PROC
+  sub rsp, 28h						; after this esp will be aligned to 16 byte boundary
+  mov qword ptr [rsp + 20h], rcx	; 5th parameter "arg" is passed on stack
+  mov r9b, bl						; opStackOfs
+  mov r8, rdi						; opStackBase
+  mov edx, esi						; programStack
+  mov ecx, eax						; syscallNum
+  mov rax, DoSyscall				; store call address of DoSyscall in rax
+  call rax
+  add rsp, 28h
+  ret
+qsyscall64 ENDP
+
+
+; Call to compiled code after setting up the register environment for the VM
+; prototype:
+; uint8_t qvmcall64(int *programStack, int *opStack, intptr_t *instructionPointers, byte *dataBase);
+
+qvmcall64 PROC
+  push rsi							; push non-volatile registers to stack
+  push rdi
+  push rbx
+  ; need to save pointer in rcx so we can write back the programData value to caller
+  push rcx
+
+  ; registers r8 and r9 have correct value already thanx to __fastcall
+  xor rbx, rbx						; opStackOfs starts out being 0
+  mov rdi, rdx						; opStack
+  mov esi, dword ptr [rcx]			; programStack
+  
+  call qword ptr [r8]				; instructionPointers[0] is also the entry point
+
+  pop rcx
+
+  mov dword ptr [rcx], esi			; write back the programStack value
+  mov al, bl						; return opStack offset
+
+  pop rbx
+  pop rdi
+  pop rsi
+  
+  ret
+qvmcall64 ENDP
+
+end