qvmcall64 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. qvmcall64 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.
Not all non-volatile registers were actually saved and restored, leading to a few registers being trashed after calling the vm instructions.
All non-volatile registers have been added.
- 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
