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 /* 27 * Author: David B. Golub, Carnegie Mellon University 28 * Date: 7/90 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 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(valuep) 49 db_expr_t *valuep; 50 { 51 int t; 52 53 t = db_read_token(); 54 if (t == tIDENT) { 55 if (!db_value_of_name(db_tok_string, valuep)) { 56 db_error("Symbol not found\n"); 57 /*NOTREACHED*/ 58 } 59 return (TRUE); 60 } 61 if (t == tNUMBER) { 62 *valuep = (db_expr_t)db_tok_number; 63 return (TRUE); 64 } 65 if (t == tDOT) { 66 *valuep = (db_expr_t)db_dot; 67 return (TRUE); 68 } 69 if (t == tDOTDOT) { 70 *valuep = (db_expr_t)db_prev; 71 return (TRUE); 72 } 73 if (t == tPLUS) { 74 *valuep = (db_expr_t) db_next; 75 return (TRUE); 76 } 77 if (t == tDITTO) { 78 *valuep = (db_expr_t)db_last_addr; 79 return (TRUE); 80 } 81 if (t == tDOLLAR) { 82 if (!db_get_variable(valuep)) 83 return (FALSE); 84 return (TRUE); 85 } 86 if (t == tLPAREN) { 87 if (!db_expression(valuep)) { 88 db_error("Syntax error\n"); 89 /*NOTREACHED*/ 90 } 91 t = db_read_token(); 92 if (t != tRPAREN) { 93 db_error("Syntax error\n"); 94 /*NOTREACHED*/ 95 } 96 return (TRUE); 97 } 98 db_unread_token(t); 99 return (FALSE); 100 } 101 102 static boolean_t 103 db_unary(valuep) 104 db_expr_t *valuep; 105 { 106 int t; 107 108 t = db_read_token(); 109 if (t == tMINUS) { 110 if (!db_unary(valuep)) { 111 db_error("Syntax error\n"); 112 /*NOTREACHED*/ 113 } 114 *valuep = -*valuep; 115 return (TRUE); 116 } 117 if (t == tSTAR) { 118 /* indirection */ 119 if (!db_unary(valuep)) { 120 db_error("Syntax error\n"); 121 /*NOTREACHED*/ 122 } 123 *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *), FALSE); 124 return (TRUE); 125 } 126 db_unread_token(t); 127 return (db_term(valuep)); 128 } 129 130 static boolean_t 131 db_mult_expr(valuep) 132 db_expr_t *valuep; 133 { 134 db_expr_t lhs, rhs; 135 int t; 136 137 if (!db_unary(&lhs)) 138 return (FALSE); 139 140 t = db_read_token(); 141 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 142 if (!db_term(&rhs)) { 143 db_error("Syntax error\n"); 144 /*NOTREACHED*/ 145 } 146 if (t == tSTAR) 147 lhs *= rhs; 148 else { 149 if (rhs == 0) { 150 db_error("Divide by 0\n"); 151 /*NOTREACHED*/ 152 } 153 if (t == tSLASH) 154 lhs /= rhs; 155 else if (t == tPCT) 156 lhs %= rhs; 157 else 158 lhs = ((lhs+rhs-1)/rhs)*rhs; 159 } 160 t = db_read_token(); 161 } 162 db_unread_token(t); 163 *valuep = lhs; 164 return (TRUE); 165 } 166 167 static boolean_t 168 db_add_expr(valuep) 169 db_expr_t *valuep; 170 { 171 db_expr_t lhs, rhs; 172 int t; 173 174 if (!db_mult_expr(&lhs)) 175 return (FALSE); 176 177 t = db_read_token(); 178 while (t == tPLUS || t == tMINUS) { 179 if (!db_mult_expr(&rhs)) { 180 db_error("Syntax error\n"); 181 /*NOTREACHED*/ 182 } 183 if (t == tPLUS) 184 lhs += rhs; 185 else 186 lhs -= rhs; 187 t = db_read_token(); 188 } 189 db_unread_token(t); 190 *valuep = lhs; 191 return (TRUE); 192 } 193 194 static boolean_t 195 db_shift_expr(valuep) 196 db_expr_t *valuep; 197 { 198 db_expr_t lhs, rhs; 199 int t; 200 201 if (!db_add_expr(&lhs)) 202 return (FALSE); 203 204 t = db_read_token(); 205 while (t == tSHIFT_L || t == tSHIFT_R) { 206 if (!db_add_expr(&rhs)) { 207 db_error("Syntax error\n"); 208 /*NOTREACHED*/ 209 } 210 if (rhs < 0) { 211 db_error("Negative shift amount\n"); 212 /*NOTREACHED*/ 213 } 214 if (t == tSHIFT_L) 215 lhs <<= rhs; 216 else { 217 /* Shift right is unsigned */ 218 lhs = (unsigned) lhs >> rhs; 219 } 220 t = db_read_token(); 221 } 222 db_unread_token(t); 223 *valuep = lhs; 224 return (TRUE); 225 } 226 227 int 228 db_expression(valuep) 229 db_expr_t *valuep; 230 { 231 return (db_shift_expr(valuep)); 232 } 233