diff -r 41cb5b80416e -r e1f0ebd2d9ec stage4/generate_c/generate_c_tempvardecl.cc --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/stage4/generate_c/generate_c_tempvardecl.cc Wed Oct 24 17:39:51 2007 +0200 @@ -0,0 +1,179 @@ +/* + * (c) 2003 Mario de Sousa + * + * Offered to the public under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General + * Public License for more details. + * + * This code is made available on the understanding that it will not be + * used in safety-critical situations without a full and competent review. + */ + +/* + * An IEC 61131-3 IL and ST compiler. + * + * Based on the + * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10) + * + */ + + +/* + * Declare temporary variables to be later used as output parameters + * in function calls for which not all output parameters were + * defined in the original (st or il) source code. + * + * This is part of the 4th stage that generates + * a c++ source program equivalent to the IL and ST + * code. + */ + + + + +class temp_var_name_c { + private: + int counter; + + public: + void reset(void) {counter = 0;} + temp_var_name_c(void) {reset();} + + public: + std::string *new_name(void) { + std::string *new_str = new std::string(TEMP_VAR); + /* yikes!!! How to convert an int to a string elegantly??? + * Right now I (Mario) can only think of snprintf() + * C++ must have a more elegant method! + */ + int int_str_size = snprintf(NULL, 0, "%d", counter); + if (int_str_size <= 0) ERROR; + char *int_str = (char *)malloc(int_str_size+1); + if (snprintf(int_str, int_str_size+1, "%d", counter++) >= int_str_size+1) ERROR; + *new_str += int_str; + free(int_str); + return new_str; + } + +}; + + + +/***********************************************************************/ +/***********************************************************************/ +/***********************************************************************/ +/***********************************************************************/ + + + +/* Some function calls in the body of functions or function blocks + * may leave some parameters to their default values, and + * ignore some output parameters of the function being called. + * Our conversion of ST functions to C++ does not contemplate that, + * i.e. each called function must get all it's input and output + * parameters set correctly. + * For input parameters we merely need to call the function with + * the apropriate default value, but for output parameters + * we must create temporary variables to hold the output value. + * + * We declare all the temporary output variables at the begining of + * the body of each function or function block, and use them as + * in function calls later on as they become necessary... + * Note that we cannot create these variables just before a function + * call, as the function call itself may be integrated within an + * expression, or another function call! + * + * The variables are declared in the exact same order in which they + * will be used later on during the function calls, which allows us + * to simply re-create the name that was used for the temporary variable + * instead of keeping it in some list. + * The names are recreated by the temp_var_name_factory, after reset() + * has been called! + * + * This function will genertae code similar to... + * + * INT __TMP_0 = 23; + * REAL __TMP_1 = 45.5; + * ... + */ + +class generate_c_tempvardecl_c: generate_c_typedecl_c { + public: + generate_c_tempvardecl_c(stage4out_c *s4o_ptr): generate_c_typedecl_c(s4o_ptr) {} + + void generate(symbol_c *body, temp_var_name_c *temp_var_name_factory) { + temp_var_name_factory->reset(); + function_call_iterator_c fcall_iterator(body); + for(symbol_c *finvocation = NULL; (finvocation = fcall_iterator.next()) != NULL;) { + /* get the name of the next function that gets called */ + identifier_c *fcalled_name = fcall_iterator.fname(); + /* get that function's declaration... */ + function_declaration_c *fdecl = function_symtable.find_value(fcalled_name); + if (fdecl == function_symtable.end_value()) { + function_type_t function_type = get_function_type(fcalled_name); + if (function_type == function_none) ERROR; + return; + } + /* create iterator to iterate through each of the called function's parameters... */ + function_param_iterator_c fp_iterator(fdecl); + + /* iterate through each of the called function's parameters... */ + identifier_c *param_name = NULL; + function_call_param_iterator_c function_call_param_iterator(finvocation); + for(int i = 1; (param_name = fp_iterator.next()) != NULL; i++) { + + function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction(); + if (param_direction == function_param_iterator_c::direction_in) + /* ignore input only parameters... + * we do not need to create temporary variables for these! + */ + continue; + + /* Get the value from a foo( = ) style call */ + symbol_c *param_value = function_call_param_iterator.search(param_name); + + /* Get the value from a foo() style call */ + if (param_value == NULL) + param_value = function_call_param_iterator.next(); + + if (param_value != NULL) + /* ignore output parameters to which a variable is passed... + * we do not need to create temporary variables for these! + */ + continue; + + symbol_c *param_type = fp_iterator.param_type(); + + /* get the parameter's default value */ + param_value = fp_iterator.default_value(); + + /* If no default value specified in function declaration, + * get the default value of this variable's type + */ + if (param_value == NULL) + param_value = (symbol_c *)param_type->accept(*type_initial_value_c::instance()); + if (param_value == NULL) ERROR; + + /* now declare a temporary variable, with the correct default value... */ + s4o.print(s4o.indent_spaces); + param_type->accept(*this); + s4o.print(" "); + + std::string *temp_var_name = temp_var_name_factory->new_name(); + s4o.print(*temp_var_name); + delete temp_var_name; + + s4o.print(" = "); + param_value->accept(*this); + s4o.print(";\n"); + } + } + temp_var_name_factory->reset(); + s4o.print("\n"); + } +};