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db_access.c revision 1.15 
      1 /*	$NetBSD: db_access.c,v 1.15 2001/01/17 19:50:03 jdolecek 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 "AS IS"
     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 #include <machine/endian.h>
     37 
     38 #include <ddb/db_access.h>
     39 
     40 /*
     41  * Access unaligned data items on aligned (longword)
     42  * boundaries.
     43  */
     44 
     45 const 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 	size_t size;
     56 	boolean_t is_signed;
     57 {
     58 	char data[sizeof(db_expr_t)];
     59 	db_expr_t value;
     60 	size_t i;
     61 
     62 	db_read_bytes(addr, size, data);
     63 
     64 	value = 0;
     65 #if BYTE_ORDER == LITTLE_ENDIAN
     66 	for (i = size; i-- > 0;)
     67 #else /* BYTE_ORDER == BIG_ENDIAN */
     68 	for (i = 0; i < size; i++)
     69 #endif /* BYTE_ORDER */
     70 		value = (value << 8) + (data[i] & 0xFF);
     71 
     72 	if (size < 4 && is_signed && (value & db_extend[size]) != 0)
     73 		value |= db_extend[size];
     74 	return (value);
     75 }
     76 
     77 void
     78 db_put_value(addr, size, value)
     79 	db_addr_t addr;
     80 	size_t size;
     81 	db_expr_t value;
     82 {
     83 	char data[sizeof(db_expr_t)];
     84 	size_t i;
     85 
     86 #if BYTE_ORDER == LITTLE_ENDIAN
     87 	for (i = 0; i < size; i++)
     88 #else /* BYTE_ORDER == BIG_ENDIAN */
     89 	for (i = size; i-- > 0;)
     90 #endif /* BYTE_ORDER */
     91 	{
     92 		data[i] = value & 0xFF;
     93 		value >>= 8;
     94 	}
     95 
     96 	db_write_bytes(addr, size, data);
     97 }
     98