IABSD.fr/src/sys/ddb/db_expr.c

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• Author : deraadt
  Date : 2020-10-15 03:13:59
  Hash : 5abbae66
  Message : sick of the CMU, let's make this KNF

• sys/ddb/db_expr.c

• /*	$OpenBSD: db_expr.c,v 1.18 2020/10/15 03:14:00 deraadt Exp $	*/
  /*	$NetBSD: db_expr.c,v 1.5 1996/02/05 01:56:58 christos Exp $	*/
  
  /*
   * Mach Operating System
   * Copyright (c) 1993,1992,1991,1990 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 "AS IS"
   * 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 Mellon
   * the rights to redistribute these changes.
   *
   *	Author: David B. Golub, Carnegie Mellon University
   *	Date:	7/90
   */
  
  #include <sys/param.h>
  
  #include <machine/db_machdep.h>
  
  #include <ddb/db_lex.h>
  #include <ddb/db_access.h>
  #include <ddb/db_command.h>
  #include <ddb/db_sym.h>
  #include <ddb/db_extern.h>
  #include <ddb/db_variables.h>
  
  int db_term(db_expr_t *);
  int db_unary(db_expr_t *);
  int db_mult_expr(db_expr_t *);
  int db_add_expr(db_expr_t *);
  int db_shift_expr(db_expr_t *);
  
  int
  db_term(db_expr_t *valuep)
  {
  	int	t;
  
  	t = db_read_token();
  	if (t == tIDENT) {
  		if (db_symbol_by_name(db_tok_string, valuep) == NULL) {
  			db_error("Symbol not found\n");
  			/*NOTREACHED*/
  		}
  		return 1;
  	}
  	if (t == tNUMBER) {
  		*valuep = db_tok_number;
  		return 1;
  	}
  	if (t == tDOT) {
  		*valuep = (db_expr_t)db_dot;
  		return 1;
  	}
  	if (t == tDOTDOT) {
  		*valuep = (db_expr_t)db_prev;
  		return 1;
  	}
  	if (t == tPLUS) {
  		*valuep = (db_expr_t) db_next;
  		return 1;
  	}
  	if (t == tDITTO) {
  		*valuep = (db_expr_t)db_last_addr;
  		return 1;
  	}
  	if (t == tDOLLAR) {
  		if (!db_get_variable(valuep))
  			return 0;
  		return 1;
  	}
  	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 1;
  	}
  	db_unread_token(t);
  	return 0;
  }
  
  int
  db_unary(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 1;
  	}
  	if (t == tSTAR) {
  		/* indirection */
  		if (!db_unary(valuep)) {
  			db_error("Syntax error\n");
  			/*NOTREACHED*/
  		}
  		*valuep = db_get_value((vaddr_t)*valuep, sizeof(vaddr_t), 0);
  		return 1;
  	}
  	db_unread_token(t);
  	return (db_term(valuep));
  }
  
  int
  db_mult_expr(db_expr_t *valuep)
  {
  	db_expr_t	lhs, rhs;
  	int		t;
  
  	if (!db_unary(&lhs))
  		return 0;
  
  	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 1;
  }
  
  int
  db_add_expr(db_expr_t *valuep)
  {
  	db_expr_t	lhs, rhs;
  	int		t;
  
  	if (!db_mult_expr(&lhs))
  		return 0;
  
  	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 1;
  }
  
  int
  db_shift_expr(db_expr_t *valuep)
  {
  	db_expr_t	lhs, rhs;
  	int		t;
  
  	if (!db_add_expr(&lhs))
  		return 0;
  
  	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 1;
  }
  
  int
  db_expression(db_expr_t *valuep)
  {
  	return (db_shift_expr(valuep));
  }