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db_access.c revision 1.6 
      1 /*	$NetBSD: db_access.c,v 1.6 1994/10/09 08:19:29 mycroft 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 int db_extend[] = {	/* table for sign-extending */
     43 	0,
     44 	0xFFFFFF80,
     45 	0xFFFF8000,
     46 	0xFF800000
     47 };
     48 
     49 db_expr_t
     50 db_get_value(addr, size, is_signed)
     51 	db_addr_t	addr;
     52 	register size_t size;
     53 	boolean_t	is_signed;
     54 {
     55 	char		data[sizeof(int)];
     56 	register db_expr_t value;
     57 	register size_t i;
     58 
     59 	db_read_bytes(addr, size, data);
     60 
     61 	value = 0;
     62 #ifdef	BYTE_MSF
     63 	for (i = 0; i < size; i++)
     64 #else	/* BYTE_LSF */
     65 	for (i = size - 1; i >= 0; i--)
     66 #endif
     67 	    value = (value << 8) + (data[i] & 0xFF);
     68 
     69 	if (size < 4) {
     70 	    if (is_signed && (value & db_extend[size]) != 0)
     71 		value |= db_extend[size];
     72 	}
     73 	return (value);
     74 }
     75 
     76 void
     77 db_put_value(addr, size, value)
     78 	db_addr_t	addr;
     79 	register size_t size;
     80 	register db_expr_t value;
     81 {
     82 	char		data[sizeof(int)];
     83 	register size_t i;
     84 
     85 #ifdef	BYTE_MSF
     86 	for (i = size - 1; i >= 0; i--)
     87 #else	/* BYTE_LSF */
     88 	for (i = 0; i < size; i++)
     89 #endif
     90 	{
     91 	    data[i] = value & 0xFF;
     92 	    value >>= 8;
     93 	}
     94 
     95 	db_write_bytes(addr, size, data);
     96 }
     97