drop table if exists statemachine;
create table statemachine (
	state integer not null,
	value integer not null,
	newstate integer not null,
	newvalue integer not null,
	direction integer not null,
	primary key (state,value)
);
# 2 state busy beaver
#insert into statemachine values (0,0,1,1,1), (0,1,1,1,-1), (1,0,0,1,-1), (1,1,-1,1,0);
# 3 state busy beaver
insert into statemachine values (0,0,1,1,1), (0,1,2,1,-1), (1,0,0,1,-1), (1,1,1,1,1), (2,0,1,1,-1), (2,1,-1,1,0);

drop table if exists tape;
create table tape (
	location integer not null,
	type enum ('tape','state','finger') not null default 'tape',
	value integer not null,
	primary key (type,location)
);
insert into tape values (0,'state',0), (0,'finger',0), (0,'tape',0);

drop procedure if exists TURING;
delimiter |
CREATE PROCEDURE TURING()
BEGIN
SELECT value INTO @state FROM tape WHERE type = 'state';
SELECT value INTO @finger FROM tape WHERE type = 'finger';
SET @value = 0;
SELECT value INTO @value FROM tape WHERE type = 'tape' AND location = @finger;
REPLACE INTO tape
 SELECT 0 AS location, 'state' AS type, newstate AS value FROM statemachine WHERE state = @state AND value = @value
UNION
 SELECT 0 AS location, 'finger' AS type, @finger+direction AS value FROM statemachine WHERE state = @state AND value = @value
UNION
 SELECT @finger AS location, 'tape' AS type, newvalue AS value FROM statemachine WHERE state = @state AND value = @value;
END;
|
delimiter ;