Fixed logic for REPEAT..UNTIL

In Stage4, C code generator, REPEAT statement was generating a while loop with inverted logic

Added RETAIN qualifier to VARIABLES.CSV

Variable forcing now uses limited list and buffer instead of systematical instance tree traversal and in-tree "fvalue" to keep track of forced value for pointed variables (external, located). Pointer swapping is performed when forcing externals and located, with backup being restored when forcing is reset. Match Beremiz commit 93ad018fb602.

Fixed __SET_EXTERNAL_FB declaration in accessor.h, invoked when accessing EXTERNAL_BLOCK.VARIABLE. Macro was invoking __SET_VAR with wrong parameter count. Fixed corresponding code generator for ST. Seems similar codegen for IL is also broken, but fix would affect other (unknown) behviours -> didn't touch it.

Remove RETAIN qualifier for F_TRIG and R_TRIG 'M' variable. This is not following standard, and implicitely consumes a lot of RETAIN memory. User can explicitely qualify R_TRIG of F_TRIG instance as RETAIN if needed.

Fix in standard function library: forgot static linkage for inline __str_cmp()

Fixed in standard function library: NE_BOOL was missing.

Fixed in standard function library: String comparison was retrurning wrong result whith strings of different sizes but starting the same, or with zero length strings.

Fixed FIND Standard Character String Function. Now returns 0 in case empty string is given either for IN1 or IN2.

Reworked get_greatest_tick_count computation

Add a column to VARIABLES.CSV, containing variable (derived) type name, additionally to current last column contyaining base type name

add default NULL value to references (as suggested by anonymous in issue 62)
(Not really needed, but it is good practise...)

merge

fix issue #73: add missing overloaded functions ADD, SUB, MUL and DIV for TIME, TOD, DT, ...

remove debugging printf() introduced in previous commits

merge

fix bug introduced in previous commit (force literals to unsigned log long)

return storage of task interval back to 1 ns resolution (when calculating least common multiple et. al. of task intervals).

addendum to issue #76: detect overflow when calculating least common multiple of task intervals.

definitive fix of issue #76: remove internal overflow of u64 when calculating least common multiple of task intervals.

Test for overflow when translating task periods/intervals to integer variable.

partial fix to issue #76 - calculate task periods with 1ms (instead of 1ns) resolution. Allows for tasks with periods larger than 4.295s, but smaller than 50 days.

partial fix for issue 74: allow deref of REF in left hand side of assignment (only works in FUNCTIONS for now)

fix issue #78: IL NOT operator not working

fix issue#77 - when IL FB followed by SFC FB, non-existant error was detected in IL code.

revert commits improved performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR)

Following commits are reverted:
mjsousa 0b275a2 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- increase hardcoded limit to 499
mjsousa 2228799 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- Add comments!!
mjsousa ce81fa6 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR)"

The reason is that they cause regression in some cases (if function is
used as argument for function block, for example) and this is not
fixed for a long time.

merge

fix backup/restore functions: now also backup/restore programs instantiated to run inside tasks.

add include <time.h>, required for time_t

improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- increase hardcoded limit to 499

improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- Add comments!!

improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR)"

Fix method ./configure uses to determine bison version (did not work in bourne shell) (submitted by anonymous)"

fix bug: allow variables with names starting with 'var' to be used in the first line of POU body

Abort compilation when finding R_EDGE or F_EDGE

Fix bug: XOR operator was broken for ANY_BIT types. No XOR__[DL]WORD__[DL]WORD functions were generated.

Add some comments to code regarding backup/restore functions

fix initialization of variable (was not following ISO C++ rules)

make generating backup/restore functions a command line option (off by default).

add support for generating functions to backup/restore the internal state of the PLC.

delete unused variable.

handle POUs with no VAR .. END_VAR blocks

fix bug introduced in previous commit (matiec was unable to parse SFC code)

Fix tracking of line numbers in IL code (error messages were previously indicating incorrect line number).

Fix bug in datatype narrowing algorithm affecting IL code.

Set the symbol->token member in symbolic_variables_c objects.

Debugging helper class: print value of tokens in debugging output.

Fix bug: allow global variables of type DT (initial values for DT are not const!)

Add comment stating how to enable debug option in flex.

merge

Print error message when FB/Struct initial value contains other strcuts/FB/arrays (not yet supported by C code generator).

Do datatype checking of initial values for structures and FBs, and print error messages when compiling erroneuos source code.

fix bug in symbol_c::find_element()

Acceept structure_element_declaration_c symbol as a possible (non base type) data type

Add token references in structure_element_declaration_c

Add token reference to all symbol_c, and add list_c::find_element()

remove debug code left in by mistake in previous commit

Access elements[] in list_c through a new get_element() method.

Start implementation of datatype checking of initial values for structures and FBs.

fix wrong common_ticktime if task interval is greater than 4.3 seconds