1 /* 2 * Mach Operating System 3 * Copyright (c) 1991,1990 Carnegie Mellon University 4 * All Rights Reserved. 5 * 6 * Permission to use, copy, modify and distribute this software and its 7 * documentation is hereby granted, provided that both the copyright 8 * notice and this permission notice appear in all copies of the 9 * software, derivative works or modified versions, and any portions 10 * thereof, and that both notices appear in supporting documentation. 11 * 12 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 13 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 14 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 15 * 16 * Carnegie Mellon requests users of this software to return to 17 * 18 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 19 * School of Computer Science 20 * Carnegie Mellon University 21 * Pittsburgh PA 15213-3890 22 * 23 * any improvements or extensions that they make and grant Carnegie the 24 * rights to redistribute these changes. 25 * 26 * $FreeBSD: src/sys/ddb/db_expr.c,v 1.13 1999/08/28 00:41:07 peter Exp $ 27 * $DragonFly: src/sys/ddb/db_expr.c,v 1.4 2005/12/23 21:35:44 swildner Exp $ 28 */ 29 30 /* 31 * Author: David B. Golub, Carnegie Mellon University 32 * Date: 7/90 33 */ 34 #include <sys/param.h> 35 36 #include <ddb/ddb.h> 37 #include <ddb/db_lex.h> 38 #include <ddb/db_access.h> 39 #include <ddb/db_command.h> 40 41 static boolean_t db_add_expr (db_expr_t *valuep); 42 static boolean_t db_mult_expr (db_expr_t *valuep); 43 static boolean_t db_shift_expr (db_expr_t *valuep); 44 static boolean_t db_term (db_expr_t *valuep); 45 static boolean_t db_unary (db_expr_t *valuep); 46 47 static boolean_t 48 db_term(db_expr_t *valuep) 49 { 50 int t; 51 52 t = db_read_token(); 53 if (t == tIDENT) { 54 if (!db_value_of_name(db_tok_string, valuep)) { 55 db_error("Symbol not found\n"); 56 /*NOTREACHED*/ 57 } 58 return (TRUE); 59 } 60 if (t == tNUMBER) { 61 *valuep = (db_expr_t)db_tok_number; 62 return (TRUE); 63 } 64 if (t == tDOT) { 65 *valuep = (db_expr_t)db_dot; 66 return (TRUE); 67 } 68 if (t == tDOTDOT) { 69 *valuep = (db_expr_t)db_prev; 70 return (TRUE); 71 } 72 if (t == tPLUS) { 73 *valuep = (db_expr_t) db_next; 74 return (TRUE); 75 } 76 if (t == tDITTO) { 77 *valuep = (db_expr_t)db_last_addr; 78 return (TRUE); 79 } 80 if (t == tDOLLAR) { 81 if (!db_get_variable(valuep)) 82 return (FALSE); 83 return (TRUE); 84 } 85 if (t == tLPAREN) { 86 if (!db_expression(valuep)) { 87 db_error("Syntax error\n"); 88 /*NOTREACHED*/ 89 } 90 t = db_read_token(); 91 if (t != tRPAREN) { 92 db_error("Syntax error\n"); 93 /*NOTREACHED*/ 94 } 95 return (TRUE); 96 } 97 db_unread_token(t); 98 return (FALSE); 99 } 100 101 static boolean_t 102 db_unary(db_expr_t *valuep) 103 { 104 int t; 105 106 t = db_read_token(); 107 if (t == tMINUS) { 108 if (!db_unary(valuep)) { 109 db_error("Syntax error\n"); 110 /*NOTREACHED*/ 111 } 112 *valuep = -*valuep; 113 return (TRUE); 114 } 115 if (t == tSTAR) { 116 /* indirection */ 117 if (!db_unary(valuep)) { 118 db_error("Syntax error\n"); 119 /*NOTREACHED*/ 120 } 121 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE); 122 return (TRUE); 123 } 124 db_unread_token(t); 125 return (db_term(valuep)); 126 } 127 128 static boolean_t 129 db_mult_expr(db_expr_t *valuep) 130 { 131 db_expr_t lhs, rhs; 132 int t; 133 134 if (!db_unary(&lhs)) 135 return (FALSE); 136 137 t = db_read_token(); 138 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 139 if (!db_term(&rhs)) { 140 db_error("Syntax error\n"); 141 /*NOTREACHED*/ 142 } 143 if (t == tSTAR) 144 lhs *= rhs; 145 else { 146 if (rhs == 0) { 147 db_error("Divide by 0\n"); 148 /*NOTREACHED*/ 149 } 150 if (t == tSLASH) 151 lhs /= rhs; 152 else if (t == tPCT) 153 lhs %= rhs; 154 else 155 lhs = ((lhs+rhs-1)/rhs)*rhs; 156 } 157 t = db_read_token(); 158 } 159 db_unread_token(t); 160 *valuep = lhs; 161 return (TRUE); 162 } 163 164 static boolean_t 165 db_add_expr(db_expr_t *valuep) 166 { 167 db_expr_t lhs, rhs; 168 int t; 169 170 if (!db_mult_expr(&lhs)) 171 return (FALSE); 172 173 t = db_read_token(); 174 while (t == tPLUS || t == tMINUS) { 175 if (!db_mult_expr(&rhs)) { 176 db_error("Syntax error\n"); 177 /*NOTREACHED*/ 178 } 179 if (t == tPLUS) 180 lhs += rhs; 181 else 182 lhs -= rhs; 183 t = db_read_token(); 184 } 185 db_unread_token(t); 186 *valuep = lhs; 187 return (TRUE); 188 } 189 190 static boolean_t 191 db_shift_expr(db_expr_t *valuep) 192 { 193 db_expr_t lhs, rhs; 194 int t; 195 196 if (!db_add_expr(&lhs)) 197 return (FALSE); 198 199 t = db_read_token(); 200 while (t == tSHIFT_L || t == tSHIFT_R) { 201 if (!db_add_expr(&rhs)) { 202 db_error("Syntax error\n"); 203 /*NOTREACHED*/ 204 } 205 if (rhs < 0) { 206 db_error("Negative shift amount\n"); 207 /*NOTREACHED*/ 208 } 209 if (t == tSHIFT_L) 210 lhs <<= rhs; 211 else { 212 /* Shift right is unsigned */ 213 lhs = (unsigned) lhs >> rhs; 214 } 215 t = db_read_token(); 216 } 217 db_unread_token(t); 218 *valuep = lhs; 219 return (TRUE); 220 } 221 222 int 223 db_expression(db_expr_t *valuep) 224 { 225 return (db_shift_expr(valuep)); 226 } 227