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1 /*
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2 lwval.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 This file contains definitions associated with the expression evaluator used
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23 by LWASM.
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24
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25 The core of the entire expression handler is the opaque type LWVAL, pointers
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26 to which are passed around to keep track of values. A value may be a simple
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27 integer or it could be a more complex expression linked by operators or it
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28 could be a polynomial expression. Simple integers are merely a degenerate
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29 case of polynomials.
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30
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31 The package understands the following operations:
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32
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33 addition
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34 subtraction
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35 multiplication
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36 division
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37 modulus
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38 parentheses
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39 unary negation
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40 unary "positive"
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41 bitwise and
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42 bitwise or
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43 bitwise not (1's complement)
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44 bitwise exclusive or
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45
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46 Infix operators can be expressed as LWVAL <op> LWVAL. Thus, the order of
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47 operations is only relevant when initially parsing the expression. The order
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48 of evaluation is determined by what appears on either side of the <op> as
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49 an LWVAL may be an expression.
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50 */
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51
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52 #ifndef __lwval_h_seen__
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53 #define __lwval_h_seen__
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54
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55 typedef struct lwval LWVAL;
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56
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57 struct lwval_dt_expr
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58 {
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59 LWVAL *v1; // first value
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60 LWVAL *v2; // second value
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61 int op; // operator
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62 };
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63
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64 union lwval_dt
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65 {
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66 int lwval_int; // integer type data
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67 char *lwval_var; // pointer to variable name
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68 struct lwval_dt_expr expr; // expression
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69 };
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70
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71 enum
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72 {
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73 LWVAL_TYPE_UNDEF, // undefined
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74 LWVAL_TYPE_NAN, // not a number
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75 LWVAL_TYPE_INT, // integer
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76 LWVAL_TYPE_VAR, // variable (symbol)
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77 LWVAL_TYPE_EXPR, // expression
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78 LWVAL_TYPE_ERR // error
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79 };
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80
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81 struct lwval
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82 {
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83 int lwval_type; // data type
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84 union lwval_dt dt; // type specific stuff
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85 };
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86
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87 #ifndef __lwval_c_seen__
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88 #define __lwval_extern__ extern
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89 #else
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90 #define __lwval_extern__
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91 #endif
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92
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93 __lwval_extern__ LWVAL *lwval_construct_int(int value);
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94 __lwval_extern__ LWVAL *lwval_construct_err(int errno);
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95 __lwval_extern__ LWVAL *lwval_construct_nan(void);
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96 __lwval_extern__ LWVAL *lwval_construct_expr(LWVAL *v1, LWVAL *v2, int op);
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97 __lwval_extern__ LWVAL *lwval_construct_undef(void);
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98 __lwval_extern__ void lwval_clear(LWVAL *value);
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99 __lwval_extern__ void lwval_destroy(LWVAL *value);
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100 __lwval_extern__ void lwval_dup(LWVAL *v1, LWVAL *v2);
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101
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102 // operators - operate on v1 and v2 in order, result goes into
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103 // v1; return v1
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104 __lwval_extern__ LWVAL *lwval_add(LWVAL *v1, LWVAL *v2);
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105 __lwval_extern__ LWVAL *lwval_sub(LWVAL *v1, LWVAL *v2);
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106 __lwval_extern__ LWVAL *lwval_mul(LWVAL *v1, LWVAL *v2);
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107 __lwval_extern__ LWVAL *lwval_div(LWVAL *v1, LWVAL *v2);
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108 __lwval_extern__ LWVAL *lwval_mod(LWVAL *v1, LWVAL *v2);
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109 __lwval_extern__ LWVAL *lwval_neg(LWVAL *v1);
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110
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111 #undef __lwval_extern__
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112
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113 #endif //__lwval_h_seen__
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