Add check bison version in configure.ac file.
To build correctly matiec we need bison greater or equals than 2.4 version.
Now the "configure" script is able to check if system has correctly requirements.
(* Following taken directly from the IEC 61131.3 draft standard *)
(*
* An IEC 61131-3 IL and ST compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*)
(*
* This is part of the library conatining the functions
* and function blocks defined in the standard.
*
* Edge detection function blocks
* ------------------------------
*)
FUNCTION_BLOCK R_TRIG
VAR_INPUT CLK: BOOL; END_VAR
VAR_OUTPUT Q: BOOL; END_VAR
VAR RETAIN M: BOOL; END_VAR
Q := CLK AND NOT M;
M := CLK;
END_FUNCTION_BLOCK
FUNCTION_BLOCK F_TRIG
VAR_INPUT CLK: BOOL; END_VAR
VAR_OUTPUT Q: BOOL; END_VAR
VAR RETAIN M: BOOL; END_VAR
Q := NOT CLK AND NOT M;
M := NOT CLK;
END_FUNCTION_BLOCK