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: releng/9.0/sys/ddb/db_expr.c 195699 2009-07-14 22:48:30Z rwatson $");
   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_value_of_name_pcpu(db_tok_string, valuep) &&
   56                 !db_value_of_name_vnet(db_tok_string, valuep)) {
   57                 db_error("Symbol not found\n");
   58                 /*NOTREACHED*/
   59             }
   60             return (TRUE);
   61         }
   62         if (t == tNUMBER) {
   63             *valuep = (db_expr_t)db_tok_number;
   64             return (TRUE);
   65         }
   66         if (t == tDOT) {
   67             *valuep = (db_expr_t)db_dot;
   68             return (TRUE);
   69         }
   70         if (t == tDOTDOT) {
   71             *valuep = (db_expr_t)db_prev;
   72             return (TRUE);
   73         }
   74         if (t == tPLUS) {
   75             *valuep = (db_expr_t) db_next;
   76             return (TRUE);
   77         }
   78         if (t == tDITTO) {
   79             *valuep = (db_expr_t)db_last_addr;
   80             return (TRUE);
   81         }
   82         if (t == tDOLLAR) {
   83             if (!db_get_variable(valuep))
   84                 return (FALSE);
   85             return (TRUE);
   86         }
   87         if (t == tLPAREN) {
   88             if (!db_expression(valuep)) {
   89                 db_error("Syntax error\n");
   90                 /*NOTREACHED*/
   91             }
   92             t = db_read_token();
   93             if (t != tRPAREN) {
   94                 db_error("Syntax error\n");
   95                 /*NOTREACHED*/
   96             }
   97             return (TRUE);
   98         }
   99         db_unread_token(t);
  100         return (FALSE);
  101 }
  102 
  103 static boolean_t
  104 db_unary(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(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(db_expr_t *valuep)
  168 {
  169         db_expr_t       lhs, rhs;
  170         int             t;
  171 
  172         if (!db_mult_expr(&lhs))
  173             return (FALSE);
  174 
  175         t = db_read_token();
  176         while (t == tPLUS || t == tMINUS) {
  177             if (!db_mult_expr(&rhs)) {
  178                 db_error("Syntax error\n");
  179                 /*NOTREACHED*/
  180             }
  181             if (t == tPLUS)
  182                 lhs += rhs;
  183             else
  184                 lhs -= rhs;
  185             t = db_read_token();
  186         }
  187         db_unread_token(t);
  188         *valuep = lhs;
  189         return (TRUE);
  190 }
  191 
  192 static boolean_t
  193 db_shift_expr(db_expr_t *valuep)
  194 {
  195         db_expr_t       lhs, rhs;
  196         int             t;
  197 
  198         if (!db_add_expr(&lhs))
  199             return (FALSE);
  200 
  201         t = db_read_token();
  202         while (t == tSHIFT_L || t == tSHIFT_R) {
  203             if (!db_add_expr(&rhs)) {
  204                 db_error("Syntax error\n");
  205                 /*NOTREACHED*/
  206             }
  207             if (rhs < 0) {
  208                 db_error("Negative shift amount\n");
  209                 /*NOTREACHED*/
  210             }
  211             if (t == tSHIFT_L)
  212                 lhs <<= rhs;
  213             else {
  214                 /* Shift right is unsigned */
  215                 lhs = (unsigned) lhs >> rhs;
  216             }
  217             t = db_read_token();
  218         }
  219         db_unread_token(t);
  220         *valuep = lhs;
  221         return (TRUE);
  222 }
  223 
  224 int
  225 db_expression(db_expr_t *valuep)
  226 {
  227         return (db_shift_expr(valuep));
  228 }

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

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sys/ddb/db_expr.c