sys/ddb/db_expr.c

   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  * $DragonFly: src/sys/ddb/db_expr.c,v 1.4 2005/12/23 21:35:44 swildner Exp $
  28  */
  29
  30 /*
  31  *      Author: David B. Golub, Carnegie Mellon University
  32  *      Date:   7/90
  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(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(db_expr_t *valuep)
 103 {
 104         int     t;
 105
 106         t = db_read_token();
 107         if (t == tMINUS) {
 108             if (!db_unary(valuep)) {
 109                 db_error("Syntax error\n");
 110                 /*NOTREACHED*/
 111             }
 112             *valuep = -*valuep;
 113             return (TRUE);
 114         }
 115         if (t == tSTAR) {
 116             /* indirection */
 117             if (!db_unary(valuep)) {
 118                 db_error("Syntax error\n");
 119                 /*NOTREACHED*/
 120             }
 121             *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
 122             return (TRUE);
 123         }
 124         db_unread_token(t);
 125         return (db_term(valuep));
 126 }
 127
 128 static boolean_t
 129 db_mult_expr(db_expr_t *valuep)
 130 {
 131         db_expr_t       lhs, rhs;
 132         int             t;
 133
 134         *valuep = 0;    /* silence gcc */
 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(db_expr_t *valuep)
 168 {
 169         db_expr_t       lhs, rhs;
 170         int             t;
 171
 172         *valuep = 0;    /* silence gcc */
 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(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(db_expr_t *valuep)
 228 {
 229         return (db_shift_expr(valuep));
 230 }