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 */ 28 29 /* 30 * Author: David B. Golub, Carnegie Mellon University 31 * Date: 7/90 32 */ 33 #include <sys/param.h> 34 35 #include <ddb/ddb.h> 36 #include <ddb/db_lex.h> 37 #include <ddb/db_access.h> 38 #include <ddb/db_command.h> 39 40 static boolean_t db_add_expr __P((db_expr_t *valuep)); 41 static boolean_t db_mult_expr __P((db_expr_t *valuep)); 42 static boolean_t db_shift_expr __P((db_expr_t *valuep)); 43 static boolean_t db_term __P((db_expr_t *valuep)); 44 static boolean_t db_unary __P((db_expr_t *valuep)); 45 46 static boolean_t 47 db_term(valuep) 48 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(valuep) 103 db_expr_t *valuep; 104 { 105 int t; 106 107 t = db_read_token(); 108 if (t == tMINUS) { 109 if (!db_unary(valuep)) { 110 db_error("Syntax error\n"); 111 /*NOTREACHED*/ 112 } 113 *valuep = -*valuep; 114 return (TRUE); 115 } 116 if (t == tSTAR) { 117 /* indirection */ 118 if (!db_unary(valuep)) { 119 db_error("Syntax error\n"); 120 /*NOTREACHED*/ 121 } 122 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE); 123 return (TRUE); 124 } 125 db_unread_token(t); 126 return (db_term(valuep)); 127 } 128 129 static boolean_t 130 db_mult_expr(valuep) 131 db_expr_t *valuep; 132 { 133 db_expr_t lhs, rhs; 134 int t; 135 136 if (!db_unary(&lhs)) 137 return (FALSE); 138 139 t = db_read_token(); 140 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 141 if (!db_term(&rhs)) { 142 db_error("Syntax error\n"); 143 /*NOTREACHED*/ 144 } 145 if (t == tSTAR) 146 lhs *= rhs; 147 else { 148 if (rhs == 0) { 149 db_error("Divide by 0\n"); 150 /*NOTREACHED*/ 151 } 152 if (t == tSLASH) 153 lhs /= rhs; 154 else if (t == tPCT) 155 lhs %= rhs; 156 else 157 lhs = ((lhs+rhs-1)/rhs)*rhs; 158 } 159 t = db_read_token(); 160 } 161 db_unread_token(t); 162 *valuep = lhs; 163 return (TRUE); 164 } 165 166 static boolean_t 167 db_add_expr(valuep) 168 db_expr_t *valuep; 169 { 170 db_expr_t lhs, rhs; 171 int t; 172 173 if (!db_mult_expr(&lhs)) 174 return (FALSE); 175 176 t = db_read_token(); 177 while (t == tPLUS || t == tMINUS) { 178 if (!db_mult_expr(&rhs)) { 179 db_error("Syntax error\n"); 180 /*NOTREACHED*/ 181 } 182 if (t == tPLUS) 183 lhs += rhs; 184 else 185 lhs -= rhs; 186 t = db_read_token(); 187 } 188 db_unread_token(t); 189 *valuep = lhs; 190 return (TRUE); 191 } 192 193 static boolean_t 194 db_shift_expr(valuep) 195 db_expr_t *valuep; 196 { 197 db_expr_t lhs, rhs; 198 int t; 199 200 if (!db_add_expr(&lhs)) 201 return (FALSE); 202 203 t = db_read_token(); 204 while (t == tSHIFT_L || t == tSHIFT_R) { 205 if (!db_add_expr(&rhs)) { 206 db_error("Syntax error\n"); 207 /*NOTREACHED*/ 208 } 209 if (rhs < 0) { 210 db_error("Negative shift amount\n"); 211 /*NOTREACHED*/ 212 } 213 if (t == tSHIFT_L) 214 lhs <<= rhs; 215 else { 216 /* Shift right is unsigned */ 217 lhs = (unsigned) lhs >> rhs; 218 } 219 t = db_read_token(); 220 } 221 db_unread_token(t); 222 *valuep = lhs; 223 return (TRUE); 224 } 225 226 int 227 db_expression(valuep) 228 db_expr_t *valuep; 229 { 230 return (db_shift_expr(valuep)); 231 } 232