Removed all patch kit headers, sccsid and rcsid strings, put $Id$ in, some

[unix-history] / sys / ddb / db_expr.c

/* 
* Mach Operating System
* Copyright (c) 1991,1990 Carnegie Mellon University
* All Rights Reserved.
* 
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
* 
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
* CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
* 
* Carnegie Mellon requests users of this software to return to
* 
*  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
*  School of Computer Science
*  Carnegie Mellon University
*  Pittsburgh PA 15213-3890
* 
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
*      $Id$
*/

/*
*      Author: David B. Golub, Carnegie Mellon University
*      Date:   7/90
*/
#include "param.h"
#include "proc.h"
#include <machine/db_machdep.h>
#include <ddb/db_lex.h>
#include <ddb/db_access.h>
#include <ddb/db_command.h>

boolean_t
db_term(valuep)
       db_expr_t *valuep;
{
       int     t;

       t = db_read_token();
       if (t == tIDENT) {
           if (!db_value_of_name(db_tok_string, valuep)) {
               db_error("Symbol not found\n");
               /*NOTREACHED*/
           }
           return (TRUE);
       }
       if (t == tNUMBER) {
           *valuep = (db_expr_t)db_tok_number;
           return (TRUE);
       }
       if (t == tDOT) {
           *valuep = (db_expr_t)db_dot;
           return (TRUE);
       }
       if (t == tDOTDOT) {
           *valuep = (db_expr_t)db_prev;
           return (TRUE);
       }
       if (t == tPLUS) {
           *valuep = (db_expr_t) db_next;
           return (TRUE);
       }
       if (t == tDITTO) {
           *valuep = (db_expr_t)db_last_addr;
           return (TRUE);
       }
       if (t == tDOLLAR) {
           if (!db_get_variable(valuep))
               return (FALSE);
           return (TRUE);
       }
       if (t == tLPAREN) {
           if (!db_expression(valuep)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           t = db_read_token();
           if (t != tRPAREN) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           return (TRUE);
       }
       db_unread_token(t);
       return (FALSE);
}

boolean_t
db_unary(valuep)
       db_expr_t *valuep;
{
       int     t;

       t = db_read_token();
       if (t == tMINUS) {
           if (!db_unary(valuep)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           *valuep = -*valuep;
           return (TRUE);
       }
       if (t == tSTAR) {
           /* indirection */
           if (!db_unary(valuep)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
           return (TRUE);
       }
       db_unread_token(t);
       return (db_term(valuep));
}

boolean_t
db_mult_expr(valuep)
       db_expr_t *valuep;
{
       db_expr_t       lhs, rhs;
       int             t;

       if (!db_unary(&lhs))
           return (FALSE);

       t = db_read_token();
       while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
           if (!db_term(&rhs)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           if (t == tSTAR)
               lhs *= rhs;
           else {
               if (rhs == 0) {
                   db_error("Divide by 0\n");
                   /*NOTREACHED*/
               }
               if (t == tSLASH)
                   lhs /= rhs;
               else if (t == tPCT)
                   lhs %= rhs;
               else
                   lhs = ((lhs+rhs-1)/rhs)*rhs;
           }
           t = db_read_token();
       }
       db_unread_token(t);
       *valuep = lhs;
       return (TRUE);
}

boolean_t
db_add_expr(valuep)
       db_expr_t *valuep;
{
       db_expr_t       lhs, rhs;
       int             t;

       if (!db_mult_expr(&lhs))
           return (FALSE);

       t = db_read_token();
       while (t == tPLUS || t == tMINUS) {
           if (!db_mult_expr(&rhs)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           if (t == tPLUS)
               lhs += rhs;
           else
               lhs -= rhs;
           t = db_read_token();
       }
       db_unread_token(t);
       *valuep = lhs;
       return (TRUE);
}

boolean_t
db_shift_expr(valuep)
       db_expr_t *valuep;
{
       db_expr_t       lhs, rhs;
       int             t;

       if (!db_add_expr(&lhs))
           return (FALSE);

       t = db_read_token();
       while (t == tSHIFT_L || t == tSHIFT_R) {
           if (!db_add_expr(&rhs)) {
               db_error("Syntax error\n");
               /*NOTREACHED*/
           }
           if (rhs < 0) {
               db_error("Negative shift amount\n");
               /*NOTREACHED*/
           }
           if (t == tSHIFT_L)
               lhs <<= rhs;
           else {
               /* Shift right is unsigned */
               lhs = (unsigned) lhs >> rhs;
           }
           t = db_read_token();
       }
       db_unread_token(t);
       *valuep = lhs;
       return (TRUE);
}

int
db_expression(valuep)
       db_expr_t *valuep;
{
       return (db_shift_expr(valuep));
}