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 /*
   27  *      Author: David B. Golub, Carnegie Mellon University
   28  *      Date:   7/90
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD$");
   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(valuep)
   49         db_expr_t *valuep;
   50 {
   51         int     t;
   52 
   53         t = db_read_token();
   54         if (t == tIDENT) {
   55             if (!db_value_of_name(db_tok_string, valuep)) {
   56                 db_error("Symbol not found\n");
   57                 /*NOTREACHED*/
   58             }
   59             return (TRUE);
   60         }
   61         if (t == tNUMBER) {
   62             *valuep = (db_expr_t)db_tok_number;
   63             return (TRUE);
   64         }
   65         if (t == tDOT) {
   66             *valuep = (db_expr_t)db_dot;
   67             return (TRUE);
   68         }
   69         if (t == tDOTDOT) {
   70             *valuep = (db_expr_t)db_prev;
   71             return (TRUE);
   72         }
   73         if (t == tPLUS) {
   74             *valuep = (db_expr_t) db_next;
   75             return (TRUE);
   76         }
   77         if (t == tDITTO) {
   78             *valuep = (db_expr_t)db_last_addr;
   79             return (TRUE);
   80         }
   81         if (t == tDOLLAR) {
   82             if (!db_get_variable(valuep))
   83                 return (FALSE);
   84             return (TRUE);
   85         }
   86         if (t == tLPAREN) {
   87             if (!db_expression(valuep)) {
   88                 db_error("Syntax error\n");
   89                 /*NOTREACHED*/
   90             }
   91             t = db_read_token();
   92             if (t != tRPAREN) {
   93                 db_error("Syntax error\n");
   94                 /*NOTREACHED*/
   95             }
   96             return (TRUE);
   97         }
   98         db_unread_token(t);
   99         return (FALSE);
  100 }
  101 
  102 static boolean_t
  103 db_unary(valuep)
  104         db_expr_t *valuep;
  105 {
  106         int     t;
  107 
  108         t = db_read_token();
  109         if (t == tMINUS) {
  110             if (!db_unary(valuep)) {
  111                 db_error("Syntax error\n");
  112                 /*NOTREACHED*/
  113             }
  114             *valuep = -*valuep;
  115             return (TRUE);
  116         }
  117         if (t == tSTAR) {
  118             /* indirection */
  119             if (!db_unary(valuep)) {
  120                 db_error("Syntax error\n");
  121                 /*NOTREACHED*/
  122             }
  123             *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *), FALSE);
  124             return (TRUE);
  125         }
  126         db_unread_token(t);
  127         return (db_term(valuep));
  128 }
  129 
  130 static boolean_t
  131 db_mult_expr(valuep)
  132         db_expr_t *valuep;
  133 {
  134         db_expr_t       lhs, rhs;
  135         int             t;
  136 
  137         if (!db_unary(&lhs))
  138             return (FALSE);
  139 
  140         t = db_read_token();
  141         while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
  142             if (!db_term(&rhs)) {
  143                 db_error("Syntax error\n");
  144                 /*NOTREACHED*/
  145             }
  146             if (t == tSTAR)
  147                 lhs *= rhs;
  148             else {
  149                 if (rhs == 0) {
  150                     db_error("Divide by 0\n");
  151                     /*NOTREACHED*/
  152                 }
  153                 if (t == tSLASH)
  154                     lhs /= rhs;
  155                 else if (t == tPCT)
  156                     lhs %= rhs;
  157                 else
  158                     lhs = ((lhs+rhs-1)/rhs)*rhs;
  159             }
  160             t = db_read_token();
  161         }
  162         db_unread_token(t);
  163         *valuep = lhs;
  164         return (TRUE);
  165 }
  166 
  167 static boolean_t
  168 db_add_expr(valuep)
  169         db_expr_t *valuep;
  170 {
  171         db_expr_t       lhs, rhs;
  172         int             t;
  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(valuep)
  196         db_expr_t *valuep;
  197 {
  198         db_expr_t       lhs, rhs;
  199         int             t;
  200 
  201         if (!db_add_expr(&lhs))
  202             return (FALSE);
  203 
  204         t = db_read_token();
  205         while (t == tSHIFT_L || t == tSHIFT_R) {
  206             if (!db_add_expr(&rhs)) {
  207                 db_error("Syntax error\n");
  208                 /*NOTREACHED*/
  209             }
  210             if (rhs < 0) {
  211                 db_error("Negative shift amount\n");
  212                 /*NOTREACHED*/
  213             }
  214             if (t == tSHIFT_L)
  215                 lhs <<= rhs;
  216             else {
  217                 /* Shift right is unsigned */
  218                 lhs = (unsigned) lhs >> rhs;
  219             }
  220             t = db_read_token();
  221         }
  222         db_unread_token(t);
  223         *valuep = lhs;
  224         return (TRUE);
  225 }
  226 
  227 int
  228 db_expression(valuep)
  229         db_expr_t *valuep;
  230 {
  231         return (db_shift_expr(valuep));
  232 }

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

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