#include "factor.h"

void init_interpreter(void)
{
	callframe.quot = F;
	callframe.scan = 0;
	callframe.end = 0;
	thrown_error = F;
}

INLINE void push_callframe(void)
{
	*(cs++) = callframe;
}

INLINE void set_callframe(CELL quot)
{
	type_check(QUOTATION_TYPE,quot);
	F_ARRAY *untagged = untag_array_fast(quot);
	callframe.quot = quot;
	callframe.scan = AREF(untagged,0);
	callframe.end = AREF(untagged,array_capacity(untagged));
}

#define TAIL_CALL_P (callframe.scan == callframe.end)

void call(CELL quot)
{
	if(quot == F) return;
	if(!TAIL_CALL_P) push_callframe();
	set_callframe(quot);
}

/* Called from interpreter() */
void handle_error(void)
{
	if(!throwing) return;

	throwing = false;
	gc_off = false;
	extra_roots = stack_chain->extra_roots;

	if(thrown_keep_stacks)
	{
		ds = thrown_ds;
		rs = thrown_rs;
	}
	else
		fix_stacks();

	dpush(thrown_error);
	dpush(thrown_native_stack_trace);

	/* Push the callframe if the error was thrown by a tail call,
	so that we don't lose it */
	if(TAIL_CALL_P) push_callframe();

	/* Notify any 'catch' blocks */
	set_callframe(userenv[BREAK_ENV]);
}

void interpreter_loop(void)
{
	for(;;)
	{
		/* done current quotation? */
		if(callframe.scan == callframe.end)
		{
			/* done with the whole stack? */
			if(cs_bot == cs)
			{
				/* if we don't have a callback to return to,
				throw an error */
				if(stack_chain->next)
					return;
				else
					simple_error(ERROR_CS_UNDERFLOW,F,F);
			}
			/* return to caller quotation */
			else
				callframe = *(--cs);
		}
		else
		{
			/* look at current object */
			CELL next = get(callframe.scan);
			callframe.scan += CELLS;

			/* execute words, push literals on data stack */
			switch(TAG(next))
			{
			case WORD_TYPE:
				execute(untag_word_fast(next));
				break;
			case WRAPPER_TYPE:
				dpush(untag_wrapper_fast(next)->object);
				break;
			default:
				dpush(next);
				break;
			}
		}
	}
}

void interpreter(void)
{
	stack_chain->native_stack_pointer = native_stack_pointer();
	SETJMP(stack_chain->toplevel);
	handle_error();
	interpreter_loop();
}

/* Called by compiled callbacks after nest_stacks() and boxing registers */
void run_callback(CELL quot)
{
	call(quot);
	run();
}

/* XT of deferred words */
void undefined(F_WORD* word)
{
	simple_error(ERROR_UNDEFINED_WORD,tag_word(word),F);
}

/* XT of compound definitions */
void docol(F_WORD* word)
{
	call(word->def);
}

/* pushes word parameter */
void dosym(F_WORD* word)
{
	dpush(word->def);
}

void primitive_execute(void)
{
	execute(untag_word(dpop()));
}

void primitive_call(void)
{
	call(dpop());
}

void primitive_ifte(void)
{
	ds -= CELLS * 3;
	call(get(ds + CELLS) == F ? get(ds + CELLS * 3) : get(ds + CELLS * 2));
}

void primitive_dispatch(void)
{
	F_ARRAY *a = untag_array_fast(dpop());
	F_FIXNUM n = untag_fixnum_fast(dpop());
	call(get(AREF(a,n)));
}

void primitive_getenv(void)
{
	F_FIXNUM e = untag_fixnum_fast(dpeek());
	drepl(userenv[e]);
}

void primitive_setenv(void)
{
	F_FIXNUM e = untag_fixnum_fast(dpop());
	CELL value = dpop();
	userenv[e] = value;
}

void primitive_exit(void)
{
	exit(to_fixnum(dpop()));
}

void primitive_os_env(void)
{
	char *name = unbox_char_string();
	char *value = getenv(name);
	if(value == NULL)
		dpush(F);
	else
		box_char_string(value);
}

void primitive_eq(void)
{
	CELL lhs = dpop();
	CELL rhs = dpeek();
	drepl((lhs == rhs) ? T : F);
}

void primitive_millis(void)
{
	box_unsigned_8(current_millis());
}

void primitive_type(void)
{
	drepl(tag_fixnum(type_of(dpeek())));
}

void primitive_tag(void)
{
	drepl(tag_fixnum(TAG(dpeek())));
}

void primitive_slot(void)
{
	F_FIXNUM slot = untag_fixnum_fast(dpop());
	CELL obj = UNTAG(dpop());
	dpush(get(SLOT(obj,slot)));
}

void primitive_set_slot(void)
{
	F_FIXNUM slot = untag_fixnum_fast(dpop());
	CELL obj = UNTAG(dpop());
	CELL value = dpop();
	set_slot(obj,slot,value);
}

void primitive_clone(void)
{
	CELL size = object_size(dpeek());
	void *new_obj = allot(size);
	CELL tag = TAG(dpeek());
	memcpy(new_obj,(void*)UNTAG(dpeek()),size);
	drepl(RETAG(new_obj,tag));
}

void fatal_error(char* msg, CELL tagged)
{
	fprintf(stderr,"fatal_error: %s %lx\n",msg,tagged);
	exit(1);
}

void critical_error(char* msg, CELL tagged)
{
	fprintf(stderr,"You have triggered a bug in Factor. Please report.\n");
	fprintf(stderr,"critical_error: %s %lx\n",msg,tagged);
	factorbug();
}

void early_error(CELL error)
{
	if(userenv[BREAK_ENV] == F)
	{
		/* Crash at startup */
		fprintf(stderr,"You have triggered a bug in Factor. Please report.\n");
		fprintf(stderr,"early_error: ");
		print_obj(error);
		fprintf(stderr,"\n");
		factorbug();
	}
}

/* allocates memory */
CELL allot_native_stack_trace(F_COMPILED_FRAME *stack)
{
	GROWABLE_ARRAY(array);

	while(stack < stack_chain->native_stack_pointer)
	{
		CELL return_address = RETURN_ADDRESS(stack);

		if(return_address >= code_heap.segment->start
			&& return_address <= code_heap.segment->end)
		{
			REGISTER_ARRAY(array);
			CELL cell = allot_cell(return_address);
			UNREGISTER_ARRAY(array);
			GROWABLE_ADD(array,cell);
		}

		F_COMPILED_FRAME *prev = PREVIOUS_FRAME(stack);

		if(prev <= stack)
		{
			critical_error("C stack walk failed in allot_native_stack_trace",0);
			break;
		}

		stack = prev;
	}

	GROWABLE_TRIM(array);

	return tag_object(array);
}

void throw_error(CELL error, bool keep_stacks, F_COMPILED_FRAME *native_stack)
{
	early_error(error);

	REGISTER_ROOT(error);
	thrown_native_stack_trace = allot_native_stack_trace(native_stack);
	UNREGISTER_ROOT(error);

	throwing = true;
	thrown_error = error;
	thrown_keep_stacks = keep_stacks;
	thrown_ds = ds;
	thrown_rs = rs;

	/* Return to interpreter() function */
	LONGJMP(stack_chain->toplevel,1);
}

void primitive_throw(void)
{
	throw_error(dpop(),true,native_stack_pointer());
}

void primitive_die(void)
{
	fprintf(stderr,"The die word was called by the library. Unless you called it yourself,\n");
	fprintf(stderr,"you have triggered a bug in Factor. Please report.\n");
	factorbug();
}

void general_error(F_ERRORTYPE error, CELL arg1, CELL arg2,
	bool keep_stacks, F_COMPILED_FRAME *native_stack)
{
	throw_error(allot_array_4(userenv[ERROR_ENV],
		tag_fixnum(error),arg1,arg2),keep_stacks,native_stack);
}

void simple_error(F_ERRORTYPE error, CELL arg1, CELL arg2)
{
	general_error(error,arg1,arg2,true,native_stack_pointer());
}

/* Test if 'fault' is in the guard page at the top or bottom (depending on
offset being 0 or -1) of area+area_size */
bool in_page(CELL fault, CELL area, CELL area_size, int offset)
{
	int pagesize = getpagesize();
	area += area_size;
	area += offset * pagesize;

	return fault >= area && fault <= area + pagesize;
}

void memory_protection_error(CELL addr, int signal, F_COMPILED_FRAME *native_stack)
{
	gc_off = true;

	if(in_page(addr, ds_bot, 0, -1))
		general_error(ERROR_DS_UNDERFLOW,F,F,false,native_stack);
	else if(in_page(addr, ds_bot, ds_size, 0))
		general_error(ERROR_DS_OVERFLOW,F,F,false,native_stack);
	else if(in_page(addr, rs_bot, 0, -1))
		general_error(ERROR_RS_UNDERFLOW,F,F,false,native_stack);
	else if(in_page(addr, rs_bot, rs_size, 0))
		general_error(ERROR_RS_OVERFLOW,F,F,false,native_stack);
	else if(in_page(addr, (CELL)cs_bot, 0, -1))
		general_error(ERROR_CS_UNDERFLOW,F,F,false,native_stack);
	else if(in_page(addr, (CELL)cs_bot, cs_size, 0))
		general_error(ERROR_CS_OVERFLOW,F,F,false,native_stack);
	else if(in_page(addr, nursery->end, 0, 0))
		critical_error("allot() missed GC check",0);
	else if(in_page(addr, extra_roots_region->start, 0, -1))
		critical_error("local root underflow",0);
	else if(in_page(addr, extra_roots_region->end, 0, 0))
		critical_error("local root overflow",0);
	else
		signal_error(signal,native_stack);
}

void signal_error(int signal, F_COMPILED_FRAME *native_stack)
{
	gc_off = true;
	general_error(ERROR_SIGNAL,tag_fixnum(signal),F,false,native_stack);
}

void type_error(CELL type, CELL tagged)
{
	simple_error(ERROR_TYPE,tag_fixnum(type),tagged);
}

void divide_by_zero_error(void)
{
	simple_error(ERROR_DIVIDE_BY_ZERO,F,F);
}

void memory_error(void)
{
	simple_error(ERROR_MEMORY,F,F);
}