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 (db_expr_t *valuep); 41 static boolean_t db_mult_expr (db_expr_t *valuep); 42 static boolean_t db_shift_expr (db_expr_t *valuep); 43 static boolean_t db_term (db_expr_t *valuep); 44 static boolean_t db_unary (db_expr_t *valuep); 45 46 static boolean_t 47 db_term(db_expr_t *valuep) 48 { 49 int t; 50 51 t = db_read_token(); 52 if (t == tIDENT) { 53 if (!db_value_of_name(db_tok_string, valuep)) { 54 db_error("Symbol not found\n"); 55 /*NOTREACHED*/ 56 } 57 return (TRUE); 58 } 59 if (t == tNUMBER) { 60 *valuep = (db_expr_t)db_tok_number; 61 return (TRUE); 62 } 63 if (t == tDOT) { 64 *valuep = (db_expr_t)db_dot; 65 return (TRUE); 66 } 67 if (t == tDOTDOT) { 68 *valuep = (db_expr_t)db_prev; 69 return (TRUE); 70 } 71 if (t == tPLUS) { 72 *valuep = (db_expr_t) db_next; 73 return (TRUE); 74 } 75 if (t == tDITTO) { 76 *valuep = (db_expr_t)db_last_addr; 77 return (TRUE); 78 } 79 if (t == tDOLLAR) { 80 if (!db_get_variable(valuep)) 81 return (FALSE); 82 return (TRUE); 83 } 84 if (t == tLPAREN) { 85 if (!db_expression(valuep)) { 86 db_error("Syntax error\n"); 87 /*NOTREACHED*/ 88 } 89 t = db_read_token(); 90 if (t != tRPAREN) { 91 db_error("Syntax error\n"); 92 /*NOTREACHED*/ 93 } 94 return (TRUE); 95 } 96 db_unread_token(t); 97 return (FALSE); 98 } 99 100 static boolean_t 101 db_unary(db_expr_t *valuep) 102 { 103 int t; 104 105 t = db_read_token(); 106 if (t == tMINUS) { 107 if (!db_unary(valuep)) { 108 db_error("Syntax error\n"); 109 /*NOTREACHED*/ 110 } 111 *valuep = -*valuep; 112 return (TRUE); 113 } 114 if (t == tSTAR) { 115 /* indirection */ 116 if (!db_unary(valuep)) { 117 db_error("Syntax error\n"); 118 /*NOTREACHED*/ 119 } 120 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE); 121 return (TRUE); 122 } 123 db_unread_token(t); 124 return (db_term(valuep)); 125 } 126 127 static boolean_t 128 db_mult_expr(db_expr_t *valuep) 129 { 130 db_expr_t lhs, rhs; 131 int t; 132 133 *valuep = 0; /* silence gcc */ 134 135 if (!db_unary(&lhs)) 136 return (FALSE); 137 138 t = db_read_token(); 139 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 140 if (!db_term(&rhs)) { 141 db_error("Syntax error\n"); 142 /*NOTREACHED*/ 143 } 144 if (t == tSTAR) 145 lhs *= rhs; 146 else { 147 if (rhs == 0) { 148 db_error("Divide by 0\n"); 149 /*NOTREACHED*/ 150 } 151 if (t == tSLASH) 152 lhs /= rhs; 153 else if (t == tPCT) 154 lhs %= rhs; 155 else 156 lhs = roundup(lhs, rhs); 157 } 158 t = db_read_token(); 159 } 160 db_unread_token(t); 161 *valuep = lhs; 162 return (TRUE); 163 } 164 165 static boolean_t 166 db_add_expr(db_expr_t *valuep) 167 { 168 db_expr_t lhs, rhs; 169 int t; 170 171 *valuep = 0; /* silence gcc */ 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(db_expr_t *valuep) 195 { 196 db_expr_t lhs, rhs; 197 int t; 198 199 if (!db_add_expr(&lhs)) 200 return (FALSE); 201 202 t = db_read_token(); 203 while (t == tSHIFT_L || t == tSHIFT_R) { 204 if (!db_add_expr(&rhs)) { 205 db_error("Syntax error\n"); 206 /*NOTREACHED*/ 207 } 208 if (rhs < 0) { 209 db_error("Negative shift amount\n"); 210 /*NOTREACHED*/ 211 } 212 if (t == tSHIFT_L) 213 lhs <<= rhs; 214 else { 215 /* Shift right is unsigned */ 216 lhs = (unsigned) lhs >> rhs; 217 } 218 t = db_read_token(); 219 } 220 db_unread_token(t); 221 *valuep = lhs; 222 return (TRUE); 223 } 224 225 int 226 db_expression(db_expr_t *valuep) 227 { 228 return (db_shift_expr(valuep)); 229 } 230