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  */
  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 }