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 * $Id: db_expr.c,v 1.3 1993/11/25 01:30:06 wollman Exp $ 27 */ 28 29 /* 30 * Author: David B. Golub, Carnegie Mellon University 31 * Date: 7/90 32 */ 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/proc.h> 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 boolean_t 42 db_term(valuep) 43 db_expr_t *valuep; 44 { 45 int t; 46 47 t = db_read_token(); 48 if (t == tIDENT) { 49 if (!db_value_of_name(db_tok_string, valuep)) { 50 db_error("Symbol not found\n"); 51 /*NOTREACHED*/ 52 } 53 return (TRUE); 54 } 55 if (t == tNUMBER) { 56 *valuep = (db_expr_t)db_tok_number; 57 return (TRUE); 58 } 59 if (t == tDOT) { 60 *valuep = (db_expr_t)db_dot; 61 return (TRUE); 62 } 63 if (t == tDOTDOT) { 64 *valuep = (db_expr_t)db_prev; 65 return (TRUE); 66 } 67 if (t == tPLUS) { 68 *valuep = (db_expr_t) db_next; 69 return (TRUE); 70 } 71 if (t == tDITTO) { 72 *valuep = (db_expr_t)db_last_addr; 73 return (TRUE); 74 } 75 if (t == tDOLLAR) { 76 if (!db_get_variable(valuep)) 77 return (FALSE); 78 return (TRUE); 79 } 80 if (t == tLPAREN) { 81 if (!db_expression(valuep)) { 82 db_error("Syntax error\n"); 83 /*NOTREACHED*/ 84 } 85 t = db_read_token(); 86 if (t != tRPAREN) { 87 db_error("Syntax error\n"); 88 /*NOTREACHED*/ 89 } 90 return (TRUE); 91 } 92 db_unread_token(t); 93 return (FALSE); 94 } 95 96 boolean_t 97 db_unary(valuep) 98 db_expr_t *valuep; 99 { 100 int t; 101 102 t = db_read_token(); 103 if (t == tMINUS) { 104 if (!db_unary(valuep)) { 105 db_error("Syntax error\n"); 106 /*NOTREACHED*/ 107 } 108 *valuep = -*valuep; 109 return (TRUE); 110 } 111 if (t == tSTAR) { 112 /* indirection */ 113 if (!db_unary(valuep)) { 114 db_error("Syntax error\n"); 115 /*NOTREACHED*/ 116 } 117 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE); 118 return (TRUE); 119 } 120 db_unread_token(t); 121 return (db_term(valuep)); 122 } 123 124 boolean_t 125 db_mult_expr(valuep) 126 db_expr_t *valuep; 127 { 128 db_expr_t lhs, rhs; 129 int t; 130 131 if (!db_unary(&lhs)) 132 return (FALSE); 133 134 t = db_read_token(); 135 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 136 if (!db_term(&rhs)) { 137 db_error("Syntax error\n"); 138 /*NOTREACHED*/ 139 } 140 if (t == tSTAR) 141 lhs *= rhs; 142 else { 143 if (rhs == 0) { 144 db_error("Divide by 0\n"); 145 /*NOTREACHED*/ 146 } 147 if (t == tSLASH) 148 lhs /= rhs; 149 else if (t == tPCT) 150 lhs %= rhs; 151 else 152 lhs = ((lhs+rhs-1)/rhs)*rhs; 153 } 154 t = db_read_token(); 155 } 156 db_unread_token(t); 157 *valuep = lhs; 158 return (TRUE); 159 } 160 161 boolean_t 162 db_add_expr(valuep) 163 db_expr_t *valuep; 164 { 165 db_expr_t lhs, rhs; 166 int t; 167 168 if (!db_mult_expr(&lhs)) 169 return (FALSE); 170 171 t = db_read_token(); 172 while (t == tPLUS || t == tMINUS) { 173 if (!db_mult_expr(&rhs)) { 174 db_error("Syntax error\n"); 175 /*NOTREACHED*/ 176 } 177 if (t == tPLUS) 178 lhs += rhs; 179 else 180 lhs -= rhs; 181 t = db_read_token(); 182 } 183 db_unread_token(t); 184 *valuep = lhs; 185 return (TRUE); 186 } 187 188 boolean_t 189 db_shift_expr(valuep) 190 db_expr_t *valuep; 191 { 192 db_expr_t lhs, rhs; 193 int t; 194 195 if (!db_add_expr(&lhs)) 196 return (FALSE); 197 198 t = db_read_token(); 199 while (t == tSHIFT_L || t == tSHIFT_R) { 200 if (!db_add_expr(&rhs)) { 201 db_error("Syntax error\n"); 202 /*NOTREACHED*/ 203 } 204 if (rhs < 0) { 205 db_error("Negative shift amount\n"); 206 /*NOTREACHED*/ 207 } 208 if (t == tSHIFT_L) 209 lhs <<= rhs; 210 else { 211 /* Shift right is unsigned */ 212 lhs = (unsigned) lhs >> rhs; 213 } 214 t = db_read_token(); 215 } 216 db_unread_token(t); 217 *valuep = lhs; 218 return (TRUE); 219 } 220 221 int 222 db_expression(valuep) 223 db_expr_t *valuep; 224 { 225 return (db_shift_expr(valuep)); 226 } 227