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 * Author: David B. Golub, Carnegie Mellon University 27 * Date: 7/90 28 * $Id: db_expr.c,v 1.3 1993/12/18 04:46:32 mycroft Exp $ 29 */ 30 31 #include <sys/param.h> 32 #include <sys/proc.h> 33 34 #include <machine/db_machdep.h> 35 36 #include <ddb/db_lex.h> 37 #include <ddb/db_access.h> 38 #include <ddb/db_command.h> 39 40 boolean_t 41 db_term(valuep) 42 db_expr_t *valuep; 43 { 44 int t; 45 46 t = db_read_token(); 47 if (t == tIDENT) { 48 if (!db_value_of_name(db_tok_string, valuep)) { 49 db_error("Symbol not found\n"); 50 /*NOTREACHED*/ 51 } 52 return (TRUE); 53 } 54 if (t == tNUMBER) { 55 *valuep = (db_expr_t)db_tok_number; 56 return (TRUE); 57 } 58 if (t == tDOT) { 59 *valuep = (db_expr_t)db_dot; 60 return (TRUE); 61 } 62 if (t == tDOTDOT) { 63 *valuep = (db_expr_t)db_prev; 64 return (TRUE); 65 } 66 if (t == tPLUS) { 67 *valuep = (db_expr_t) db_next; 68 return (TRUE); 69 } 70 if (t == tDITTO) { 71 *valuep = (db_expr_t)db_last_addr; 72 return (TRUE); 73 } 74 if (t == tDOLLAR) { 75 if (!db_get_variable(valuep)) 76 return (FALSE); 77 return (TRUE); 78 } 79 if (t == tLPAREN) { 80 if (!db_expression(valuep)) { 81 db_error("Syntax error\n"); 82 /*NOTREACHED*/ 83 } 84 t = db_read_token(); 85 if (t != tRPAREN) { 86 db_error("Syntax error\n"); 87 /*NOTREACHED*/ 88 } 89 return (TRUE); 90 } 91 db_unread_token(t); 92 return (FALSE); 93 } 94 95 boolean_t 96 db_unary(valuep) 97 db_expr_t *valuep; 98 { 99 int t; 100 101 t = db_read_token(); 102 if (t == tMINUS) { 103 if (!db_unary(valuep)) { 104 db_error("Syntax error\n"); 105 /*NOTREACHED*/ 106 } 107 *valuep = -*valuep; 108 return (TRUE); 109 } 110 if (t == tSTAR) { 111 /* indirection */ 112 if (!db_unary(valuep)) { 113 db_error("Syntax error\n"); 114 /*NOTREACHED*/ 115 } 116 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE); 117 return (TRUE); 118 } 119 db_unread_token(t); 120 return (db_term(valuep)); 121 } 122 123 boolean_t 124 db_mult_expr(valuep) 125 db_expr_t *valuep; 126 { 127 db_expr_t lhs, rhs; 128 int t; 129 130 if (!db_unary(&lhs)) 131 return (FALSE); 132 133 t = db_read_token(); 134 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) { 135 if (!db_term(&rhs)) { 136 db_error("Syntax error\n"); 137 /*NOTREACHED*/ 138 } 139 if (t == tSTAR) 140 lhs *= rhs; 141 else { 142 if (rhs == 0) { 143 db_error("Divide by 0\n"); 144 /*NOTREACHED*/ 145 } 146 if (t == tSLASH) 147 lhs /= rhs; 148 else if (t == tPCT) 149 lhs %= rhs; 150 else 151 lhs = ((lhs+rhs-1)/rhs)*rhs; 152 } 153 t = db_read_token(); 154 } 155 db_unread_token(t); 156 *valuep = lhs; 157 return (TRUE); 158 } 159 160 boolean_t 161 db_add_expr(valuep) 162 db_expr_t *valuep; 163 { 164 db_expr_t lhs, rhs; 165 int t; 166 167 if (!db_mult_expr(&lhs)) 168 return (FALSE); 169 170 t = db_read_token(); 171 while (t == tPLUS || t == tMINUS) { 172 if (!db_mult_expr(&rhs)) { 173 db_error("Syntax error\n"); 174 /*NOTREACHED*/ 175 } 176 if (t == tPLUS) 177 lhs += rhs; 178 else 179 lhs -= rhs; 180 t = db_read_token(); 181 } 182 db_unread_token(t); 183 *valuep = lhs; 184 return (TRUE); 185 } 186 187 boolean_t 188 db_shift_expr(valuep) 189 db_expr_t *valuep; 190 { 191 db_expr_t lhs, rhs; 192 int t; 193 194 if (!db_add_expr(&lhs)) 195 return (FALSE); 196 197 t = db_read_token(); 198 while (t == tSHIFT_L || t == tSHIFT_R) { 199 if (!db_add_expr(&rhs)) { 200 db_error("Syntax error\n"); 201 /*NOTREACHED*/ 202 } 203 if (rhs < 0) { 204 db_error("Negative shift amount\n"); 205 /*NOTREACHED*/ 206 } 207 if (t == tSHIFT_L) 208 lhs <<= rhs; 209 else { 210 /* Shift right is unsigned */ 211 lhs = (unsigned) lhs >> rhs; 212 } 213 t = db_read_token(); 214 } 215 db_unread_token(t); 216 *valuep = lhs; 217 return (TRUE); 218 } 219 220 int 221 db_expression(valuep) 222 db_expr_t *valuep; 223 { 224 return (db_shift_expr(valuep)); 225 } 226