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db_access.c revision 1.15.4.1 
      1 /*	$NetBSD: db_access.c,v 1.15.4.1 2002/01/10 19:52:36 thorpej 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/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: db_access.c,v 1.15.4.1 2002/01/10 19:52:36 thorpej Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/proc.h>
     37 
     38 #include <machine/db_machdep.h>		/* type definitions */
     39 #include <machine/endian.h>
     40 
     41 #include <ddb/db_access.h>
     42 
     43 /*
     44  * Access unaligned data items on aligned (longword)
     45  * boundaries.
     46  */
     47 
     48 const int db_extend[] = {	/* table for sign-extending */
     49 	0,
     50 	0xFFFFFF80,
     51 	0xFFFF8000,
     52 	0xFF800000
     53 };
     54 
     55 db_expr_t
     56 db_get_value(addr, size, is_signed)
     57 	db_addr_t addr;
     58 	size_t size;
     59 	boolean_t is_signed;
     60 {
     61 	char data[sizeof(db_expr_t)];
     62 	db_expr_t value;
     63 	size_t i;
     64 
     65 	db_read_bytes(addr, size, data);
     66 
     67 	value = 0;
     68 #if BYTE_ORDER == LITTLE_ENDIAN
     69 	for (i = size; i-- > 0;)
     70 #else /* BYTE_ORDER == BIG_ENDIAN */
     71 	for (i = 0; i < size; i++)
     72 #endif /* BYTE_ORDER */
     73 		value = (value << 8) + (data[i] & 0xFF);
     74 
     75 	if (size < 4 && is_signed && (value & db_extend[size]) != 0)
     76 		value |= db_extend[size];
     77 	return (value);
     78 }
     79 
     80 void
     81 db_put_value(addr, size, value)
     82 	db_addr_t addr;
     83 	size_t size;
     84 	db_expr_t value;
     85 {
     86 	char data[sizeof(db_expr_t)];
     87 	size_t i;
     88 
     89 #if BYTE_ORDER == LITTLE_ENDIAN
     90 	for (i = 0; i < size; i++)
     91 #else /* BYTE_ORDER == BIG_ENDIAN */
     92 	for (i = size; i-- > 0;)
     93 #endif /* BYTE_ORDER */
     94 	{
     95 		data[i] = value & 0xFF;
     96 		value >>= 8;
     97 	}
     98 
     99 	db_write_bytes(addr, size, data);
    100 }
    101