db_expr.c

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    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: releng/5.0/sys/ddb/db_expr.c 98815 2002-06-25 15:59:24Z tmm $
   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(valuep)
   48         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(valuep)
  103         db_expr_t *valuep;
  104 {
  105         int     t;
  106 
  107         t = db_read_token();
  108         if (t == tMINUS) {
  109             if (!db_unary(valuep)) {
  110                 db_error("Syntax error\n");
  111                 /*NOTREACHED*/
  112             }
  113             *valuep = -*valuep;
  114             return (TRUE);
  115         }
  116         if (t == tSTAR) {
  117             /* indirection */
  118             if (!db_unary(valuep)) {
  119                 db_error("Syntax error\n");
  120                 /*NOTREACHED*/
  121             }
  122             *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *), FALSE);
  123             return (TRUE);
  124         }
  125         db_unread_token(t);
  126         return (db_term(valuep));
  127 }
  128 
  129 static boolean_t
  130 db_mult_expr(valuep)
  131         db_expr_t *valuep;
  132 {
  133         db_expr_t       lhs, rhs;
  134         int             t;
  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(valuep)
  168         db_expr_t *valuep;
  169 {
  170         db_expr_t       lhs, rhs;
  171         int             t;
  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(valuep)
  195         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(valuep)
  228         db_expr_t *valuep;
  229 {
  230         return (db_shift_expr(valuep));
  231 }

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FreeBSD/Linux Kernel Cross Reference sys/ddb/db_expr.c

FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_expr.c