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1 /*
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2 expr.h
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3 Copyright © 2008 William Astle
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4
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5 This file is part of LWASM.
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6
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7 LWASM is free software: you can redistribute it and/or modify it under the
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8 terms of the GNU General Public License as published by the Free Software
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9 Foundation, either version 3 of the License, or (at your option) any later
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10 version.
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11
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12 This program is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 You should have received a copy of the GNU General Public License along with
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18 this program. If not, see <http://www.gnu.org/licenses/>.
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19 */
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20
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21 /*
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22 Definitions for expression evaluator
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23 */
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24
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25 #ifndef __expr_h_seen__
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26 #define __expr_h_seen__
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27
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28 #ifndef __expr_c_seen__
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29 #define __expr_E__ extern
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30 #else
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31 #define __expr_E__
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32 #endif
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33
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34 // term types
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35 #define LWASM_TERM_NONE 0
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36 #define LWASM_TERM_OPER 1 // an operator
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37 #define LWASM_TERM_INT 2 // 32 bit signed integer
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38 #define LWASM_TERM_SYM 3 // symbol reference
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39 #define LWASM_TERM_SECBASE 4 // section base reference
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40
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41 // operator types
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42 #define LWASM_OPER_NONE 0
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43 #define LWASM_OPER_PLUS 1 // +
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44 #define LWASM_OPER_MINUS 2 // -
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45 #define LWASM_OPER_TIMES 3 // *
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46 #define LWASM_OPER_DIVIDE 4 // /
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47 #define LWASM_OPER_MOD 5 // %
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48 #define LWASM_OPER_INTDIV 6 // \ (don't end line with \)
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49 #define LWASM_OPER_BWAND 7 // bitwise AND
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50 #define LWASM_OPER_BWOR 8 // bitwise OR
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51 #define LWASM_OPER_BWXOR 9 // bitwise XOR
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52 #define LWASM_OPER_AND 10 // boolean AND
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53 #define LWASM_OPER_OR 11 // boolean OR
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54 #define LWASM_OPER_NEG 12 // - unary negation (2's complement)
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55 #define LWASM_OPER_COM 13 // ^ unary 1's complement
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56
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57
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58 // term structure
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59 typedef struct lwasm_expr_term_s
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60 {
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61 int term_type; // type of term (see above)
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62 char *symbol; // name of a symbol
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63 int value; // value of the term (int) or operator number (OPER)
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64 } lwasm_expr_term_t;
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65
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66 // type for an expression evaluation stack
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67 typedef struct lwasm_expr_stack_node_s lwasm_expr_stack_node_t;
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68 struct lwasm_expr_stack_node_s
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69 {
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70 lwasm_expr_term_t *term;
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71 lwasm_expr_stack_node_t *prev;
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72 lwasm_expr_stack_node_t *next;
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73 };
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74
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75 typedef struct lwasm_expr_stack_s
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76 {
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77 lwasm_expr_stack_node_t *head;
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78 lwasm_expr_stack_node_t *tail;
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79 } lwasm_expr_stack_t;
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80
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81 __expr_E__ void lwasm_expr_term_free(lwasm_expr_term_t *t);
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82 __expr_E__ lwasm_expr_term_t *lwasm_expr_term_create_oper(int oper);
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83 __expr_E__ lwasm_expr_term_t *lwasm_expr_term_create_sym(char *sym);
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84 __expr_E__ lwasm_expr_term_t *lwasm_expr_term_create_int(int val);
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85 __expr_E__ lwasm_expr_term_t *lwasm_expr_term_create_secbase(void);
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86 __expr_E__ lwasm_expr_term_t *lwasm_expr_term_dup(lwasm_expr_term_t *t);
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87
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88 __expr_E__ void lwasm_expr_stack_free(lwasm_expr_stack_t *s);
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89 __expr_E__ lwasm_expr_stack_t *lwasm_expr_stack_create(void);
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90
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91 __expr_E__ void lwasm_expr_stack_push(lwasm_expr_stack_t *s, lwasm_expr_term_t *t);
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92 __expr_E__ lwasm_expr_term_t *lwasm_expr_stack_pop(lwasm_expr_stack_t *s);
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93
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94 /*
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95 Evaluate an expression. The result is an lwasm_expr_stack_t pointer. If the
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96 expression evaluates to a constant result, the stack will contain exactly one
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97 value which will be a constant. Otherwise, the stack will contain the
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98 expression with all operations that can be evaluated completely evaluated.
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99 You must call lwasm_expr_stack_free() on the result when you are finished
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100 with it.
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101 */
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102 __expr_E__ lwasm_expr_stack_t *lwasm_expr_eval(const char *inp, const char **outp, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state);
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103
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104 // simplify expression
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105 __expr_E__ int lwasm_expr_reval(lwasm_expr_stack_t *s, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state);
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106
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107 // useful macros
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108 // is the expression "simple" (one term)?
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109 #define lwasm_expr_is_simple(s) ((s) -> head == (s) -> tail)
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110
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111 // is the expression constant?
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112 #define lwasm_expr_is_constant(s) (lwasm_expr_is_simple(s) && (!((s) -> head) || (s) -> head -> term -> term_type == LWASM_TERM_INT))
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113
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114 // get the constant value of an expression or 0 if not constant
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115 #define lwasm_expr_get_value(s) (lwasm_expr_is_constant(s) ? ((s) -> head ? (s) -> head -> term -> value : 0) : 0)
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116
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117 #undef __expr_E__
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118
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119 #endif // __expr_h_seen__
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