/* -*- mode:c -*- */

#include "compiler.h"
#include "plat/plat.h"
#include "lib/std.h"

#include <dasm_proto.h>
#include <dasm_x86.h>

#define value_size sizeof (value_t)

|.arch x86;

|.macro setup, nvars;
| push ebp;
| mov ebp, esp;
| sub esp, (value_size * nvars);
|.endmacro;

|.macro cleanup;
| mov esp, ebp;
| pop ebp;
| ret;
|.endmacro;

dasm_State *d;
unsigned int npc = 8;

struct function *find_function (struct environment *env, char *name)
{
	struct function *f = env->first;

	while ( strcmp (f->name, name) != 0 )
	{
		if ( f->prev )
			f = f->prev;
		else
			return NULL;
	}

	return f;
}

void compile (value_t val)
{
	|.section code;
	dasm_init (&d, DASM_MAXSECTION);

	|.globals lbl_;
	void *labels[ lbl__MAX ];
	dasm_setupglobal (&d, labels, lbl__MAX);

	|.actionlist lisp_actions;
	dasm_setup (&d, lisp_actions);

	dasm_growpc (&d, npc);

	struct environment env;
	env.first = NULL;
	char *name = "main";
	load_std (&env);

	printval (val, 0);
	compile_expr_to_func (&env, name, val, &d);

	value_t (*fun)() = find_function (&env, name)->def0;
	printval (fun (), 0);
}

void compile_expression (struct environment *env, struct local *local,
                         value_t val, dasm_State **Dst)
{
	if ( integerp (val) || stringp (val) || symbolp (val) )
	{
		| mov eax, val;
	}
	else if ( listp (val) )
	{
		value_t fsym = car (val);

		if ( !symbolp (fsym) )
		{
			err ("function name must be a symbol");
		}

		struct function *func = find_function (env, (char *) (fsym ^ SYMBOL_TAG));
		value_t args = cdr (val);
		int nargs = length (args);

		if ( nargs != func->nargs )
			err ("wrong number of args");

		for ( int i = length (args) - 1; i >= 0; i-- )
		{
			compile_expression (env, local, elt (args, i), Dst);
			| push eax;
		}

		| mov ebx, (func->code_addr);
		| call ebx;
		| add esp, (nargs * 4);
		// result in eax
	}
}

void compile_expr_to_func (struct environment *env, char *name, value_t val,
                           dasm_State **Dst)
{
	| setup 0;

	struct local local;
	compile_expression (env, &local, val, Dst);
	
	| cleanup;

	add_function (env, name, link (Dst), 0);
}