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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) 2003-2011  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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 *  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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/* Do constant folding...

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 *

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 * I.e., Determine the value of all expressions in which only constant values (i.e. literals) are used.

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 * The (constant) result of each operation is stored (annotated) in the respective operation symbol 

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 * (e.g.: add_expression_c) in the abstract syntax tree,

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 *

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 * For example:

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 *       2 + 3         -> the constant value '5'    is stored in the add_expression_c symbol.

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 *       22.2 - 5.0    -> the constant value '17.2' is stored in the add_expression_c symbol.

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 *       etc...

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 *

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 *

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 * NOTE 1 

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 *      Some operations and constants can have multiple data types. For example,

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 *        1 AND 0

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 *      may be either a BOOL, BYTE, WORD or LWORD.

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 *

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 *      The same happens with 

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 *        1 + 2

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 *      which may be signed (e.g. INT) or unsigned (UINT)

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 *

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 *      For the above reason, instead of storing a single constant value, we actually store 4:

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 *        - bool

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 *        - uint64

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 *        -  int64

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 *        - real64

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 *

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 *      Additionally, since the result of an operation may result in an overflow, we actually

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 *      store the result inside a struct (defined in absyntax.hh)

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 *

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 *             ** During stage 3 (semantic analysis/checking) we will be doing constant folding.

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 *              * That algorithm will anotate the abstract syntax tree with the result of operations

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 *              * on literals (i.e. 44 + 55 will store the result 99).

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 *              * Since the same source code (e.g. 1 + 0) may actually be a BOOL or an ANY_INT,

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 *              * or an ANY_BIT, we need to handle all possibilities, and determine the result of the

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 *              * operation assuming each type.

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 *              * For this reason, we have one entry for each possible type, with some expressions

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 *              * having more than one entry filled in!

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 *              **

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 *             typedef enum { cs_undefined,   // not defined --> const_value is not valid!

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 *                            cs_const_value, // const value is valid

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 *                            cs_overflow     // result produced overflow or underflow --> const_value is not valid!

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 *                          } const_status_t;

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 *    

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 *             typedef struct {

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 *                 const_status_t status;

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 *                 real64_t       value; 

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 *             } const_value_real64_t;

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 *             const_value_real64_t *const_value_real64; // when NULL --> UNDEFINED

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 *             

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 *             typedef struct {

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 *                 const_status_t status;

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 *                 int64_t        value; 

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 *             } const_value_int64_t;

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 *             const_value_int64_t *const_value_int64; // when NULL --> UNDEFINED

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 *             

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 *             typedef struct {

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 *                 const_status_t status;

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 *                 uint64_t       value; 

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 *             } const_value_uint64_t;

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 *             const_value_uint64_t *const_value_uint64; // when NULL --> UNDEFINED

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 *             

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 *             typedef struct {

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 *                 const_status_t status;

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 *                 bool           value; 

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 *             } const_value_bool_t;

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 *             const_value_bool_t *const_value_bool; // when NULL --> UNDEFINED

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 *

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 *

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 *

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 * NOTE 2 

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 *    This file does not print out any error messages!

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 *    We cannot really print out error messages when we find an overflow. Since each operation

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 *    (symbol in the absract syntax tree for that operation) will have up to 4 constant results,

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 *    it may happen that some of them overflow, while other do not.

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 *    We must wait for data type checking to determine the exact data type of each expression

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 *    before we can decide whether or not we should print out an overflow error message.

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 *

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 *    For this reason, this visitor merely annotates the abstract syntax tree, and leaves the

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 *    actuall printing of errors for the print_datatype_errors_c class!

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 */

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#include "constant_folding.hh"

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#include <stdlib.h> /* required for malloc() */

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#include <string.h>  /* required for strlen() */

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// #include <stdlib.h>  /* required for atoi() */

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#include <errno.h>   /* required for errno */

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#include "../main.hh" // required for uint8_t, real_64_t, ..., and the macros NAN, INFINITY, INT8_MAX, REAL32_MAX, ... */

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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 NEW_CVALUE(dtype, symbol) \

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 (symbol->const_value_##dtype) = new(symbol_c::const_value_##dtype##_t); \

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 if ((symbol->const_value_##dtype) == NULL) ERROR; \

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 (symbol->const_value_##dtype)->status = symbol_c::cs_undefined;

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#define SET_CVALUE(dtype, symbol, new_value)  ((symbol)->const_value_##dtype->value) = new_value; ((symbol)->const_value_##dtype->status) = symbol_c::cs_const_value;

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#define GET_CVALUE(dtype, symbol)             ((symbol)->const_value_##dtype->value)

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#define SET_OVFLOW(dtype, symbol)             ((symbol)->const_value_##dtype->status) = symbol_c::cs_overflow

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    /* The following test is correct in the presence of a NULL pointer, as the logical evaluation will be suspended as soon as the first condition is false! */

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#define VALID_CVALUE(dtype, symbol)           ((NULL != (symbol)->const_value_##dtype) && (symbol_c::cs_const_value == (symbol)->const_value_##dtype->status))

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#define ISZERO_CVALUE(dtype, symbol)          ((VALID_CVALUE(dtype, symbol)) && (GET_CVALUE(dtype, symbol) == 0))

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#define DO_BINARY_OPER(dtype, oper, otype)\

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	if (VALID_CVALUE(dtype, symbol->r_exp) && VALID_CVALUE(dtype, symbol->l_exp)) {                                \

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		NEW_CVALUE(otype, symbol);                                                                             \

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		SET_CVALUE(otype, symbol, GET_CVALUE(dtype, symbol->l_exp) oper GET_CVALUE(dtype, symbol->r_exp));     \

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	}

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#define DO_UNARY_OPER(dtype, oper, arg)\

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	if (VALID_CVALUE(dtype, arg)) {                                                                                \

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		NEW_CVALUE(dtype, symbol);                                                                             \

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		SET_CVALUE(dtype, symbol, oper GET_CVALUE(dtype, arg));                                                \

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	}

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

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

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

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/***            convert string to numerical value                    ***/

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

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

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

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  /* To allow the compiler to be portable, we cannot assume that int64_t is mapped onto long long int,

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   * so we cannot call strtoll() and strtoull() in extract_int64() and extract_uint64().

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   *

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   * So, we create our own strtouint64() and strtoint64() functions.

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   * (We actually call them matiec_strtoint64() so they will not clash with any function

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   *  that may be added to the standard library in the future).

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   * We actually create several of each, and let the compiler choose which is the correct one,

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   * by having it resolve the call to the overloaded function. For the C++ compiler to be able

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   * to resolve this ambiguity, we need to add a dummy parameter to each function!

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   *

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   * TODO: support platforms in which int64_t is mapped onto int !! Is this really needed?

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   */

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static  int64_t matiec_strtoint64 (         long      int *dummy, const char *nptr, char **endptr, int base) {return strtol  (nptr, endptr, base);}

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static  int64_t matiec_strtoint64 (         long long int *dummy, const char *nptr, char **endptr, int base) {return strtoll (nptr, endptr, base);}

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static uint64_t matiec_strtouint64(unsigned long      int *dummy, const char *nptr, char **endptr, int base) {return strtoul (nptr, endptr, base);}

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static uint64_t matiec_strtouint64(unsigned long long int *dummy, const char *nptr, char **endptr, int base) {return strtoull(nptr, endptr, base);}

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/* extract the value of an integer from an integer_c object !! */

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/* NOTE: it must ignore underscores! */

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/* NOTE: To follow the basic structure used throughout the compiler's code, we should really be

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 * writing this as a visitor_c (and do away with the dynamic casts!), but since we only have 3 distinct 

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 * symbol class types to handle, it is probably easier to read if we write it as a standard function... 

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 */

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int64_t extract_int64_value(symbol_c *sym, bool *overflow) {

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  int64_t      ret;

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  std::string  str = "";

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  char        *endptr;

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  const char  *value;

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  int          base;

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  integer_c         *integer;

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  hex_integer_c     *hex_integer;

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  octal_integer_c   *octal_integer;

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  binary_integer_c  *binary_integer;

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   if       ((integer        = dynamic_cast<integer_c *>(sym))        != NULL) {value = integer       ->value + 0; base = 10;}

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   else  if ((hex_integer    = dynamic_cast<hex_integer_c *>(sym))    != NULL) {value = hex_integer   ->value + 3; base = 16;}

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   else  if ((octal_integer  = dynamic_cast<octal_integer_c *>(sym))  != NULL) {value = octal_integer ->value + 2; base =  8;}

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   else  if ((binary_integer = dynamic_cast<binary_integer_c *>(sym)) != NULL) {value = binary_integer->value + 2; base =  2;}

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   else  ERROR;

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  for(unsigned int i = 0; i < strlen(value); i++)

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    if (value[i] != '_')  str += value[i];

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  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

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  ret = matiec_strtoint64((int64_t *)NULL, str.c_str(), &endptr, base);

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  if (overflow != NULL)

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    *overflow = (errno == ERANGE);

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  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

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    ERROR;

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  return ret;

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}

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uint64_t extract_uint64_value(symbol_c *sym, bool *overflow) {

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  uint64_t     ret;

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  std::string  str = "";

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  char        *endptr;

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  const char  *value;

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  int          base;

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  integer_c         *integer;

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  hex_integer_c     *hex_integer;

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  octal_integer_c   *octal_integer;

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  binary_integer_c  *binary_integer;

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   if       ((integer        = dynamic_cast<integer_c *>(sym))        != NULL) {value = integer       ->value + 0; base = 10;}

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   else  if ((hex_integer    = dynamic_cast<hex_integer_c *>(sym))    != NULL) {value = hex_integer   ->value + 3; base = 16;}

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   else  if ((octal_integer  = dynamic_cast<octal_integer_c *>(sym))  != NULL) {value = octal_integer ->value + 2; base =  8;}

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   else  if ((binary_integer = dynamic_cast<binary_integer_c *>(sym)) != NULL) {value = binary_integer->value + 2; base =  2;}

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   else  ERROR;

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  for(unsigned int i = 0; i < strlen(value); i++)

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    if (value[i] != '_')  str += value[i];

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  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

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  ret = matiec_strtouint64((uint64_t *)NULL, str.c_str(), &endptr, base);

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  if (overflow != NULL)

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    *overflow = (errno == ERANGE);

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  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

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    ERROR;

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  return ret;

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}

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/* extract the value of a real from an real_c object !! */

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/* NOTE: it must ignore underscores! */

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/* From iec_bison.yy

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 *  real:

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 *   real_token		{$$ = new real_c($1, locloc(@$));}

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 * | fixed_point_token	{$$ = new real_c($1, locloc(@$));}

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 *

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 * From iec_flex.ll

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 * {real}			{yylval.ID=strdup(yytext); return real_token;}

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 * {fixed_point}		{yylval.ID=strdup(yytext); return fixed_point_token;}

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 *

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 * real		{integer}\.{integer}{exponent}

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 * fixed_point		{integer}\.{integer}

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 * exponent        [Ee]([+-]?){integer}

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 * integer         {digit}((_?{digit})*)

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 */

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real64_t extract_real_value(symbol_c *sym, bool *overflow) {

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  std::string str = "";

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  real_c *real_sym;

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  char   *endptr;

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  real64_t ret;

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  if ((real_sym = dynamic_cast<real_c *>(sym)) == NULL) ERROR;

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  for(unsigned int i = 0; i < strlen(real_sym->value); i++)

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    if (real_sym->value[i] != '_') str += real_sym->value[i];

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  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

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  #if    (real64_t  == float)

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    ret = strtof(str.c_str(),  &endptr);

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  #elif  (real64_t  == double)

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    ret = strtod(str.c_str(),  &endptr);

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  #elif  (real64_t  == long_double)

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    ret = strtold(str.c_str(), &endptr);

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  #else 

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    #error Could not determine which data type is being used for real64_t (defined in absyntax.hh). Aborting!

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  #endif

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  if (overflow != NULL)

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    *overflow = (errno == ERANGE);

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  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

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    ERROR;

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   336

  return ret;

   337

}

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   339

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

   344

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

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

   346

/***        Functions to check for overflow situation                ***/

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

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

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

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   351

   352

/* NOTE:

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 *   Most of the conditions to detect overflows on signed and unsigned integer operations were adapted from

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 *   https://www.securecoding.cert.org/confluence/display/seccode/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow?showComments=false

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 *   https://www.securecoding.cert.org/confluence/display/seccode/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap

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 */

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/* NOTE: If at all possible, all overflow tests are done by pre-condition tests, i.e. tests that 

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 *       can be run _before_ the operation is executed, and therefore without accessing the result!

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 *

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 *       The exception is for real/floating point values, that simply test if the result is NaN (not a number).

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 */

   363

   364

/* res = a + b */

   365

static void CHECK_OVERFLOW_uint64_SUM(symbol_c *res, symbol_c *a, symbol_c *b) {

   366

	if (!VALID_CVALUE(uint64, res))

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		return;

   368

	/* Test by post-condition: If sum is smaller than either operand => overflow! */

   369

	// if (GET_CVALUE(uint64, res) < GET_CVALUE(uint64, a))

   370

	/* Test by pre-condition: If (UINT64_MAX - a) < b => overflow! */

   371

	if ((UINT64_MAX - GET_CVALUE(uint64, a)) < GET_CVALUE(uint64, b))

   372

		SET_OVFLOW(uint64, res);

   373

}

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   375

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/* res = a - b */

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static void CHECK_OVERFLOW_uint64_SUB(symbol_c *res, symbol_c *a, symbol_c *b) {

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	if (!VALID_CVALUE(uint64, res))

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		return;

   380

	/* Test by post-condition: If diference is larger than a => overflow! */

   381

	// if (GET_CVALUE(uint64, res) > GET_CVALUE(uint64, a))

   382

	/* Test by pre-condition: if b > a => overflow! */

   383

	if (GET_CVALUE(uint64, b) > GET_CVALUE(uint64, a))

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		SET_OVFLOW(uint64, res);

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}

   386

   387

   388

/* res = a * b */

   389

static void CHECK_OVERFLOW_uint64_MUL(symbol_c *res, symbol_c *a, symbol_c *b) {

   390

	if (!VALID_CVALUE(uint64, res))

   391

		return;

   392

	/* Test by pre-condition: If (UINT64_MAX / a) < b => overflow! */

   393

	if ((UINT64_MAX / GET_CVALUE(uint64, a)) < GET_CVALUE(uint64, b))

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		SET_OVFLOW(uint64, res);

   395

}

   396

   397

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/* res = a / b */

   399

static void CHECK_OVERFLOW_uint64_DIV(symbol_c *res, symbol_c *a, symbol_c *b) {

   400

	if (!VALID_CVALUE(uint64, res))

   401

		return;

   402

	if (GET_CVALUE(uint64, b) == 0) /* division by zero! */

   403

		SET_OVFLOW(uint64, res);

   404

}

   405

   406

   407

/* res = a MOD b */

   408

static void CHECK_OVERFLOW_uint64_MOD(symbol_c *res, symbol_c *a, symbol_c *b) {

   409

	if (!VALID_CVALUE(uint64, res))

   410

		return;

   411

	/* no overflow condition exists, including division by zero, which IEC 61131-3 considers legal for MOD operation! */

   412

	if (false) 

   413

		SET_OVFLOW(uint64, res);

   414

}

   415

   416

   417

/* res = a + b */

   418

static void CHECK_OVERFLOW_int64_SUM(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   419

	if (!VALID_CVALUE(int64, res))

   420

		return;

   421

	int64_t a = GET_CVALUE(int64, a_ptr);

   422

	int64_t b = GET_CVALUE(int64, b_ptr);

   423

	/* The following test is valid no matter what representation is being used (e.g. two's complement, etc...) */

   424

	if (((b > 0) && (a > (INT64_MAX - b)))

   425

	 || ((b < 0) && (a < (INT64_MIN - b))))

   426

		SET_OVFLOW(int64, res);

   427

}

   428

   429

   430

/* res = a - b */

   431

static void CHECK_OVERFLOW_int64_SUB(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   432

	if (!VALID_CVALUE(int64, res))

   433

		return;

   434

	int64_t a = GET_CVALUE(int64, a_ptr);

   435

	int64_t b = GET_CVALUE(int64, b_ptr);

   436

	/* The following test is valid no matter what representation is being used (e.g. two's complement, etc...) */

   437

	if (((b > 0) && (a < (INT64_MIN + b)))

   438

	 || ((b < 0) && (a > (INT64_MAX + b))))

   439

		SET_OVFLOW(int64, res);

   440

}

   441

   442

   443

/* res = a * b */

   444

static void CHECK_OVERFLOW_int64_MUL(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   445

	if (!VALID_CVALUE(int64, res))

   446

		return;

   447

	int64_t a = GET_CVALUE(int64, a_ptr);

   448

	int64_t b = GET_CVALUE(int64, b_ptr);

   449

	if (   ( (a > 0) &&  (b > 0) &&             (a > (INT64_MAX / b))) 

   450

	    || ( (a > 0) && !(b > 0) &&             (b < (INT64_MIN / a))) 

   451

	    || (!(a > 0) &&  (b > 0) &&             (a < (INT64_MIN / b))) 

   452

	    || (!(a > 0) && !(b > 0) && (a != 0) && (b < (INT64_MAX / a))))

   453

		SET_OVFLOW(int64, res);

   454

}

   455

   456

   457

/* res = a / b */

   458

static void CHECK_OVERFLOW_int64_DIV(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   459

	if (!VALID_CVALUE(int64, res))

   460

		return;

   461

	int64_t a = GET_CVALUE(int64, a_ptr);

   462

	int64_t b = GET_CVALUE(int64, b_ptr);

   463

	if ((b == 0) || ((a == INT64_MIN) && (b == -1)))

   464

		SET_OVFLOW(int64, res);

   465

}

   466

   467

   468

/* res = a MOD b */

   469

static void CHECK_OVERFLOW_int64_MOD(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   470

	if (!VALID_CVALUE(int64, res))

   471

		return;

   472

	int64_t a = GET_CVALUE(int64, a_ptr);

   473

	int64_t b = GET_CVALUE(int64, b_ptr);

   474

	/* IEC 61131-3 standard says IN1 MOD IN2 must be equivalent to

   475

	 *  IF (IN2 = 0) THEN OUT:=0 ; ELSE OUT:=IN1 - (IN1/IN2)*IN2 ; END_IF

   476

	 *

   477

	 * Note that, when IN1 = INT64_MIN, and IN2 = -1, an overflow occurs in the division,

   478

	 * so although the MOD operation should be OK, acording to the above definition, we actually have an overflow!!

   479

	 *

   480

	 * On the other hand, division by 0 is OK!!

   481

	 */

   482

	if ((a == INT64_MIN) && (b == -1))

   483

		SET_OVFLOW(int64, res);

   484

}

   485

   486

   487

/* res = - a */

   488

static void CHECK_OVERFLOW_int64_NEG(symbol_c *res, symbol_c *a_ptr) {

   489

	if (!VALID_CVALUE(int64, res))

   490

		return;

   491

	int64_t a = GET_CVALUE(int64, a_ptr);

   492

	if (a == INT64_MIN)

   493

		SET_OVFLOW(int64, res);

   494

}

   495