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annotate src/expr.h @ 14:b28d7cb60779
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date | Thu, 23 Oct 2008 02:44:07 +0000 |
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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 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 __expr_h_seen__ |
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53 #define __expr_h_seen__ |
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54 |
14 | 55 typedef struct lwval LWVAL; |
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56 |
14 | 57 union lwval_dt |
58 { | |
59 int lwval_int; // integer type data | |
60 char *lwval_var; // pointer to variable name | |
61 }; | |
62 | |
63 enum | |
64 { | |
65 LWVAL_TYPE_NAN, // not a number | |
66 LWVAL_TYPE_INT, // integer | |
67 LWVAL_TYPE_VAR, // variable (symbol) | |
68 LWVAL_TYPE_EXPR, // expression | |
69 }; | |
70 | |
71 struct lwval | |
72 { | |
73 int lwval_type; // data type | |
74 union lwval_dt dt; // type specific stuff | |
75 }; | |
76 | |
77 #ifndef __expr_c_seen__ | |
78 #define EE extern | |
79 #else | |
80 #define EE | |
81 #endif | |
82 | |
83 EE LWVAL *lwval_construct_int(int value); | |
84 EE void lwval_destroy(LWVAL *value); | |
85 | |
86 // operators - operate on v1 and v2 in order, return in v3 | |
87 // if v3 is NULL, allocate new LWVAL and return it else just | |
88 // return v3 with new value in it | |
89 EE LWVAL *lwval_add(LWVAL *v1, LWVAL *v2, LWVAL *v3); | |
90 EE LWVAL *lwval_sub(LWVAL *v1, LWVAL *v2, LWVAL *v3); | |
91 EE LWVAL *lwval_mul(LWVAL *v1, LWVAL *v2, LWVAL *v3); | |
92 EE LWVAL *lwval_div(LWVAL *v1, LWVAL *v2, LWVAL *v3); | |
93 EE LWVAL *lwval_mod(LWVAL *v1, LWVAL *v2, LWVAL *v3); | |
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94 |
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95 #endif //__expr_h_seen__ |