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; ===========================================================================
; 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
.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);
;
; This call-stub has its own custom calling convention due to pushing all non-volatile registers
; to the stack. The game uses set/longjmp which on Windows uses "RtlUnwindEx" to unwind the callstack.
; This function cannot be unwound by default due to the custom calling convention.
; To allow unwinding, we need to add custom SEH unwind data to the function.
qvmcall64 PROC FRAME
push r12 ; push all non-volatile registers to stack
.pushreg r12
push r13
.pushreg r13
push r14
.pushreg r14
push r15
.pushreg r15
push rdi
.pushreg rdi
push rsi
.pushreg rsi
push rbx
.pushreg rbx
push rbp
.pushreg rbp
; need to save pointer in rcx so we can write back the programData value to caller
push rcx
.pushreg rcx
.endprolog ; custom unwind data ends here
; 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 rbp ; restore all non-volatile registers after the call
pop rbx
pop rsi
pop rdi
pop r15
pop r14
pop r13
pop r12
ret
qvmcall64 ENDP
end
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