1 files changed, 59 insertions, 0 deletions
diff --git a/src/asm/vm_x86_64.asm b/src/asm/vm_x86_64.asm
new file mode 100644
index 0000000..692cee9
--- /dev/null
+++ b/src/asm/vm_x86_64.asm
@@ -0,0 +1,59 @@
+; ===========================================================================
+; Copyright (C) 2011 Thilo Schulz <thilo@tjps.eu>
+; Copyright (C) 2015-2019 GrangerHub
+; 
+; This file is part of Tremulous.
+; 
+; Tremulous 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 3 of the License,
+; or (at your option) any later version.
+; 
+; Tremulous 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 Tremulous; if not, see <https://www.gnu.org/licenses/>
+; 
+; ===========================================================================
+
+; 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
+
+.code
+
+; 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