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/*

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 *  matiec - a compiler for the programming languages defined in IEC 61131-3

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 *

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 *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

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 *  Copyright (C) 2012       Manuele Conti  (conti.ma@alice.it)

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 *

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 *

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 *  This program is free software: you can redistribute it and/or modify

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 *  it under the terms of the GNU General Public License as published by

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 *  the Free Software Foundation, either version 3 of the License, or

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 *  (at your option) any later version.

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 *

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 *  This program is distributed in the hope that it will be useful,

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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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 *  You should have received a copy of the GNU General Public License

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 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

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 *

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 *

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 * This code is made available on the understanding that it will not be

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 * used in safety-critical situations without a full and competent review.

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 */

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/*

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 * An IEC 61131-3 compiler.

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 *

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 * Based on the

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 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

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 *

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 */

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/*

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 * Array Range Checking:

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 *   - Check whether array subscript values fall within the allowed range.

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 *     Note that for the checking of subscript values to work correctly, we need to have constant folding working too:

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 *     array_var[8 + 99] can not be checked without constant folding.

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 */

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#include "array_range_check.hh"

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#include <limits>  // required for std::numeric_limits<XXX>

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#define FIRST_(symbol1, symbol2) (((symbol1)->first_order < (symbol2)->first_order)   ? (symbol1) : (symbol2))

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#define  LAST_(symbol1, symbol2) (((symbol1)->last_order  > (symbol2)->last_order)    ? (symbol1) : (symbol2))

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#define STAGE3_ERROR(error_level, symbol1, symbol2, ...) {                                                                  \

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  if (current_display_error_level >= error_level) {                                                                         \

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    fprintf(stderr, "%s:%d-%d..%d-%d: error: ",                                                                             \

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            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

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                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

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    fprintf(stderr, __VA_ARGS__);                                                                                           \

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    fprintf(stderr, "\n");                                                                                                  \

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    error_count++;                                                                                                     \

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  }                                                                                                                         \

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}

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#define STAGE3_WARNING(symbol1, symbol2, ...) {                                                                             \

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    fprintf(stderr, "%s:%d-%d..%d-%d: warning: ",                                                                           \

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            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

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                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

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    fprintf(stderr, __VA_ARGS__);                                                                                           \

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    fprintf(stderr, "\n");                                                                                                  \

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    warning_found = true;                                                                                                   \

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}

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#define GET_CVALUE(dtype, symbol)             ((symbol)->const_value._##dtype.get())

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#define VALID_CVALUE(dtype, symbol)           ((symbol)->const_value._##dtype.is_valid())

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/*  The cmp_unsigned_signed function compares two numbers u and s.

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 *  It returns an integer indicating the relationship between the numbers:

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 *  - A zero value indicates that both numbers are equal.

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 *  - A value greater than zero indicates that numbers does not match and

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 *    first has a greater value.

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 *  - A value less than zero indicates that numbers does not match and

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 *    first has a lesser value.

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 */

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static inline int cmp_unsigned_signed(const uint64_t u, const int64_t s) {

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  const uint64_t INT64_MAX_uvar = INT64_MAX;

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  if (u <= INT64_MAX_uvar)

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    return ((int64_t)u - s);

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  return -1;

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}

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array_range_check_c::array_range_check_c(symbol_c *ignore) {

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	error_count = 0;

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	current_display_error_level = 0;

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	search_varfb_instance_type = NULL;

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}

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array_range_check_c::~array_range_check_c(void) {

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}

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int array_range_check_c::get_error_count() {

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	return error_count;

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}

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void array_range_check_c::check_dimension_count(array_variable_c *symbol) {

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	int dimension_count;

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	symbol_c *var_decl;

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	var_decl = search_varfb_instance_type->get_basetype_decl(symbol->subscripted_variable);

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	array_dimension_iterator_c array_dimension_iterator(var_decl);

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	for (dimension_count = 0; NULL != array_dimension_iterator.next(); dimension_count++);

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	if (dimension_count != ((list_c *)symbol->subscript_list)->n)

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		STAGE3_ERROR(0, symbol, symbol, "Number of subscripts/indexes does not match the number of subscripts/indexes in the array's declaration (array has %d indexes)", dimension_count);

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}

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void array_range_check_c::check_bounds(array_variable_c *symbol) {

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  list_c *l; /* the subscript_list */

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  symbol_c *var_decl;

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  l = (list_c *)symbol->subscript_list;

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  var_decl = search_varfb_instance_type->get_basetype_decl(symbol->subscripted_variable);

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  array_dimension_iterator_c array_dimension_iterator(var_decl);

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  for (int i =  0; i < l->n; i++) {

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    subrange_c *dimension = array_dimension_iterator.next();

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    /* mismatch between number of indexes/subscripts. This error will be caught in check_dimension_count() so we ignore it. */

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    if (NULL == dimension) 

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      return;

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    /* Check lower limit */

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    /* Repeat the same check, now for upper limit */

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  }

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}

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/*************************/

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/* B.1 - Common elements */

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/*************************/

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/**********************/

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/* B.1.3 - Data types */

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/**********************/

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/********************************/

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/* B 1.3.3 - Derived data types */

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/********************************/

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/*  signed_integer DOTDOT signed_integer */

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/* dimension will be filled in during stage 3 (array_range_check_c) with the number of elements in this subrange */

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// SYM_REF2(subrange_c, lower_limit, upper_limit, unsigned long long int dimension)

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void *array_range_check_c::visit(subrange_c *symbol) {

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	unsigned long long int dimension = 0; // we use unsigned long long instead of uint64_t since it might just happen to be larger than uint64_t in the platform used for compiling this code!!

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	/* Determine the size of the array... */

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	if        (VALID_CVALUE( int64, symbol->upper_limit) && VALID_CVALUE( int64, symbol->lower_limit)) {  

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		// do the sums in such a way that no overflow is possible... even during intermediate steps used by compiler!

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		// remember that the result (dimension) is unsigned, while the operands are signed!!

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		// dimension = GET_CVALUE( int64, symbol->upper_limit) - VALID_CVALUE( int64, symbol->lower_limit);

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		if  (GET_CVALUE( int64, symbol->lower_limit)  >   GET_CVALUE( int64, symbol->upper_limit)) {

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			STAGE3_ERROR(0, symbol, symbol, "Subrange has lower limit (%"PRId64") larger than upper limit (%"PRId64").", GET_CVALUE( int64, symbol->lower_limit), GET_CVALUE( int64, symbol->upper_limit));

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			dimension = std::numeric_limits< unsigned long long int >::max() - 1; // -1 because it will be incremented at the end of this function!! 

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		} else if (GET_CVALUE( int64, symbol->lower_limit) >= 0) {

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			dimension = GET_CVALUE( int64, symbol->upper_limit) - GET_CVALUE( int64, symbol->lower_limit);

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		} else {

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			dimension  = -GET_CVALUE( int64, symbol->lower_limit);

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			dimension +=  GET_CVALUE( int64, symbol->upper_limit);     

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		}

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	} else if (VALID_CVALUE(uint64, symbol->upper_limit) && VALID_CVALUE(uint64, symbol->lower_limit)) {

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		if  (GET_CVALUE(uint64, symbol->lower_limit)  >   GET_CVALUE(uint64, symbol->upper_limit)) {

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			STAGE3_ERROR(0, symbol, symbol, "Subrange has lower limit (%"PRIu64") larger than upper limit (%"PRIu64").", GET_CVALUE(uint64, symbol->lower_limit), GET_CVALUE(uint64, symbol->upper_limit));

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			dimension = std::numeric_limits< unsigned long long int >::max() - 1; // -1 because it will be incremented at the end of this function!! 

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		} else

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			dimension = GET_CVALUE(uint64, symbol->upper_limit) - GET_CVALUE(uint64, symbol->lower_limit); 

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	} else if (VALID_CVALUE(uint64, symbol->upper_limit) && VALID_CVALUE( int64, symbol->lower_limit)) {

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		// No need to check whether lower_limit > upper_limit, as we only reach this point if lower_limit < 0 (and upper_limit must be >= 0!)

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		if (GET_CVALUE( int64, symbol->lower_limit) >= 0) {

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			dimension = GET_CVALUE(uint64, symbol->upper_limit) - GET_CVALUE( int64, symbol->lower_limit);

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		} else {

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			unsigned long long int lower_ull;

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			lower_ull  = -GET_CVALUE( int64, symbol->lower_limit);

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			dimension  =  GET_CVALUE(uint64, symbol->upper_limit) + lower_ull;     

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			if (dimension < lower_ull)

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				STAGE3_ERROR(0, symbol, symbol, "Number of elements in array subrange exceeds maximum number of elements (%llu).", std::numeric_limits< unsigned long long int >::max());

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		}

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	} else if (!VALID_CVALUE(uint64, symbol->upper_limit) && !VALID_CVALUE( int64, symbol->upper_limit)) {

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		STAGE3_ERROR(0, symbol->upper_limit, symbol->upper_limit, "Subrange upper limit is not a constant value.");

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		// set dimension to largest possible value so we do not get any further related error messages.

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		dimension = std::numeric_limits< unsigned long long int >::max() - 1; // -1 because it will be incremented at the end of this function!! 

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	} else if (!VALID_CVALUE(uint64, symbol->lower_limit) && !VALID_CVALUE( int64, symbol->lower_limit)) {

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		STAGE3_ERROR(0, symbol->lower_limit, symbol->lower_limit, "Subrange lower limit is not a constant value.");

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		// set dimension to largest possible value so we do not get any further related error messages.

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		dimension = std::numeric_limits< unsigned long long int >::max() - 1; // -1 because it will be incremented at the end of this function!! 

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		/* NOTE: Note that both the "subrange *** limit is not a constant value" error messages are only necessary due to an extension

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		 *       that matiec supports by allowing non-literals in subrange declarations (currently only subranges in array declarations).

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		 *         e.g.:  array_var: ARRAY [1..max] of INT;   <--- illegal according to IEC 61131-1 due to the 'max' non literal

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		 *       Matiec will allow the above syntax, as long as the 'max' variable can be determined to be constant throughout

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		 *       the program execution at runtime (and not only constant when program initiates) - for example, a VAR CONSTANT

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		 *       variable.

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		 *       These two checks will verify if we were able to fold the variable into a constant value, or not.

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		 */

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	} else {ERROR;}

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	/* correct value for dimension is actually ---> dimension = upper_limit - lower_limit + 1

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	 * Up to now, we have only determined dimension = upper_limit - lower_limit

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	 * We must first check whether this last increment will cause an overflow!

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	 */

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	if (dimension == std::numeric_limits< unsigned long long int >::max())

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		STAGE3_ERROR(0, symbol, symbol, "Number of elements in array subrange exceeds maximum number of elements (%llu).", std::numeric_limits< unsigned long long int >::max());

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	/* correct value for dimension is actually ---> dimension = upper_limit - lower_limit + 1 */

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	dimension++; 

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	symbol->dimension = dimension;

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	return NULL;

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}

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/* integer '(' [array_initial_element] ')' */

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/* array_initial_element may be NULL ! */

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// SYM_REF2(array_initial_elements_c, integer, array_initial_element)

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void *array_range_check_c::visit(array_initial_elements_c *symbol) {

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	if (VALID_CVALUE( int64, symbol->integer) && (GET_CVALUE( int64, symbol->integer) < 0)) 

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		ERROR; /* the IEC 61131-3 syntax guarantees that this value will never be negative! */

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	/* TODO: check that the total number of 'initial values' does not exceed the size of the array! */

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	return NULL;

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}

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/*********************/

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/* B 1.4 - Variables */

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/*********************/

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/*************************************/

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/* B 1.4.2 - Multi-element variables */

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/*************************************/

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void *array_range_check_c::visit(array_variable_c *symbol) {

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	check_dimension_count(symbol);

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	check_bounds(symbol);

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	return NULL;

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}

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/**************************************/

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/* B 1.5 - Program organisation units */

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/**************************************/

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/***********************/

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/* B 1.5.1 - Functions */

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/***********************/

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// SYM_REF4(function_declaration_c, derived_function_name, type_name, var_declarations_list, function_body)

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void *array_range_check_c::visit(function_declaration_c *symbol) {

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	symbol->var_declarations_list->accept(*this); // required for visiting subrange_c

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	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

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	// search_var_instance_decl = new search_var_instance_decl_c(symbol);

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	symbol->function_body->accept(*this);

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	delete search_varfb_instance_type;

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	// delete search_var_instance_decl;

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	search_varfb_instance_type = NULL;

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	// search_var_instance_decl = NULL;

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	return NULL;

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}

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/*****************************/

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/* B 1.5.2 - Function blocks */

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/*****************************/

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// SYM_REF3(function_block_declaration_c, fblock_name, var_declarations, fblock_body)

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void *array_range_check_c::visit(function_block_declaration_c *symbol) {

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	symbol->var_declarations->accept(*this); // required for visiting subrange_c

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	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

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	// search_var_instance_decl = new search_var_instance_decl_c(symbol);

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	symbol->fblock_body->accept(*this);

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	delete search_varfb_instance_type;

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	// delete search_var_instance_decl;

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	search_varfb_instance_type = NULL;

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	// search_var_instance_decl = NULL;

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	return NULL;

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}

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/**********************/

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/* B 1.5.3 - Programs */

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/**********************/

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// SYM_REF3(program_declaration_c, program_type_name, var_declarations, function_block_body)

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void *array_range_check_c::visit(program_declaration_c *symbol) {

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	symbol->var_declarations->accept(*this); // required for visiting subrange_c

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	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

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	// search_var_instance_decl = new search_var_instance_decl_c(symbol);

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	symbol->function_block_body->accept(*this);

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	delete search_varfb_instance_type;

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	// delete search_var_instance_decl;

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	search_varfb_instance_type = NULL;

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	// search_var_instance_decl = NULL;

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	return NULL;

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}

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