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db_access.c revision 1.5 
      1 /*	$NetBSD: db_access.c,v 1.5 1994/06/29 06:30:55 cgd Exp $	*/
      2 
      3 /*
      4  * Mach Operating System
      5  * Copyright (c) 1991,1990 Carnegie Mellon University
      6  * All Rights Reserved.
      7  *
      8  * Permission to use, copy, modify and distribute this software and its
      9  * documentation is hereby granted, provided that both the copyright
     10  * notice and this permission notice appear in all copies of the
     11  * software, derivative works or modified versions, and any portions
     12  * thereof, and that both notices appear in supporting documentation.
     13  *
     14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
     15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     16  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     17  *
     18  * Carnegie Mellon requests users of this software to return to
     19  *
     20  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     21  *  School of Computer Science
     22  *  Carnegie Mellon University
     23  *  Pittsburgh PA 15213-3890
     24  *
     25  * any improvements or extensions that they make and grant Carnegie the
     26  * rights to redistribute these changes.
     27  *
     28  *	Author: David B. Golub, Carnegie Mellon University
     29  *	Date:	7/90
     30  */
     31 
     32 #include <sys/param.h>
     33 #include <sys/proc.h>
     34 
     35 #include <machine/db_machdep.h>		/* type definitions */
     36 
     37 /*
     38  * Access unaligned data items on aligned (longword)
     39  * boundaries.
     40  */
     41 
     42 extern void	db_read_bytes();	/* machine-dependent */
     43 extern void	db_write_bytes();	/* machine-dependent */
     44 
     45 int db_extend[] = {	/* table for sign-extending */
     46 	0,
     47 	0xFFFFFF80,
     48 	0xFFFF8000,
     49 	0xFF800000
     50 };
     51 
     52 db_expr_t
     53 db_get_value(addr, size, is_signed)
     54 	db_addr_t	addr;
     55 	register int	size;
     56 	boolean_t	is_signed;
     57 {
     58 	char		data[sizeof(int)];
     59 	register db_expr_t value;
     60 	register int	i;
     61 
     62 	db_read_bytes(addr, size, data);
     63 
     64 	value = 0;
     65 #ifdef	BYTE_MSF
     66 	for (i = 0; i < size; i++)
     67 #else	/* BYTE_LSF */
     68 	for (i = size - 1; i >= 0; i--)
     69 #endif
     70 	{
     71 	    value = (value << 8) + (data[i] & 0xFF);
     72 	}
     73 
     74 	if (size < 4) {
     75 	    if (is_signed && (value & db_extend[size]) != 0)
     76 		value |= db_extend[size];
     77 	}
     78 	return (value);
     79 }
     80 
     81 void
     82 db_put_value(addr, size, value)
     83 	db_addr_t	addr;
     84 	register int	size;
     85 	register db_expr_t value;
     86 {
     87 	char		data[sizeof(int)];
     88 	register int	i;
     89 
     90 #ifdef	BYTE_MSF
     91 	for (i = size - 1; i >= 0; i--)
     92 #else	/* BYTE_LSF */
     93 	for (i = 0; i < size; i++)
     94 #endif
     95 	{
     96 	    data[i] = value & 0xFF;
     97 	    value >>= 8;
     98 	}
     99 
    100 	db_write_bytes(addr, size, data);
    101 }
    102 
    103