Paste: win64 seh

#include "master.hpp"

namespace factor {

typedef unsigned char UBYTE;

const UBYTE UNW_FLAG_EHANDLER = 0x1;

struct UNWIND_INFO {
	UBYTE Version:3;
	UBYTE Flags:5;
	UBYTE SizeOfProlog;
	UBYTE CountOfCodes;
	UBYTE FrameRegister:4;
	UBYTE FrameOffset:4;
	ULONG ExceptionHandler;
	ULONG ExceptionData[1];
};

struct seh_data {
	UNWIND_INFO unwind_info;
	RUNTIME_FUNCTION func;
	UBYTE handler[32];
};

void factor_vm::c_to_factor_toplevel(cell quot)
{
	/* The annoying thing about Win64 SEH is that the offsets in
	 * function tables are 32-bit integers, and the exception handler
	 * itself must reside between the start and end pointers, so
	 * we stick everything at the beginning of the code heap and
	 * generate a small trampoline that jumps to the real
	 * exception handler. */

	seh_data *seh_area = (seh_data *)code->seh_area;
	cell base = code->seg->start;

	/* Should look at generating this with the Factor assembler */

	/* mov rax,0 */
	seh_area->handler[0] = 0x48;
	seh_area->handler[1] = 0xb8;
	seh_area->handler[2] = 0x0;
	seh_area->handler[3] = 0x0;
	seh_area->handler[4] = 0x0;
	seh_area->handler[5] = 0x0;
	seh_area->handler[6] = 0x0;
	seh_area->handler[7] = 0x0;
	seh_area->handler[8] = 0x0;
	seh_area->handler[9] = 0x0;

	/* jmp rax */
	seh_area->handler[10] = 0x48;
	seh_area->handler[11] = 0xff;
	seh_area->handler[12] = 0xe0;

	/* Store address of exception handler in the operand of the 'mov' */
	cell handler = (cell)&factor::exception_handler;
	memcpy(&seh_area->handler[2],&handler,sizeof(cell));

	UNWIND_INFO *unwind_info = &seh_area->unwind_info;
	unwind_info->Version = 1;
	unwind_info->Flags = UNW_FLAG_EHANDLER;
	unwind_info->SizeOfProlog = 0;
	unwind_info->CountOfCodes = 0;
	unwind_info->FrameRegister = 0;
	unwind_info->FrameOffset = 0;
	unwind_info->ExceptionHandler = (DWORD)((cell)&seh_area->handler[0] - base);
	unwind_info->ExceptionData[0] = 0;

	RUNTIME_FUNCTION *func = &seh_area->func;
	func->BeginAddress = 0;
	func->EndAddress = (DWORD)(code->seg->end - base);
	func->UnwindData = (DWORD)((cell)&seh_area->unwind_info - base);

	if(!RtlAddFunctionTable(func,1,base))
		fatal_error("RtlAddFunctionTable() failed",0);

	c_to_factor(quot);

	if(!RtlDeleteFunctionTable(func))
		fatal_error("RtlDeleteFunctionTable() failed",0);
}

}