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db_access.c revision 1.1 
      1 /*
      2  * Mach Operating System
      3  * Copyright (c) 1991,1990 Carnegie Mellon University
      4  * All Rights Reserved.
      5  *
      6  * Permission to use, copy, modify and distribute this software and its
      7  * documentation is hereby granted, provided that both the copyright
      8  * notice and this permission notice appear in all copies of the
      9  * software, derivative works or modified versions, and any portions
     10  * thereof, and that both notices appear in supporting documentation.
     11  *
     12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
     13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     15  *
     16  * Carnegie Mellon requests users of this software to return to
     17  *
     18  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     19  *  School of Computer Science
     20  *  Carnegie Mellon University
     21  *  Pittsburgh PA 15213-3890
     22  *
     23  * any improvements or extensions that they make and grant Carnegie the
     24  * rights to redistribute these changes.
     25  */
     26 /*
     27  * HISTORY
     28  * $Log: db_access.c,v $
     29  * Revision 1.1  1993/03/21 09:45:37  cgd
     30  * Initial revision
     31  *
     32  * Revision 1.1  1992/03/25  21:44:50  pace
     33  * Initial revision
     34  *
     35  * Revision 2.3  91/02/05  17:05:44  mrt
     36  * 	Changed to new Mach copyright
     37  * 	[91/01/31  16:16:22  mrt]
     38  *
     39  * Revision 2.2  90/08/27  21:48:20  dbg
     40  * 	Fix type declarations.
     41  * 	[90/08/07            dbg]
     42  * 	Created.
     43  * 	[90/07/25            dbg]
     44  *
     45  */
     46 /*
     47  *	Author: David B. Golub, Carnegie Mellon University
     48  *	Date:	7/90
     49  */
     50 #include "param.h"
     51 #include "proc.h"
     52 #include <machine/db_machdep.h>		/* type definitions */
     53 
     54 /*
     55  * Access unaligned data items on aligned (longword)
     56  * boundaries.
     57  */
     58 
     59 extern void	db_read_bytes();	/* machine-dependent */
     60 extern void	db_write_bytes();	/* machine-dependent */
     61 
     62 int db_extend[] = {	/* table for sign-extending */
     63 	0,
     64 	0xFFFFFF80,
     65 	0xFFFF8000,
     66 	0xFF800000
     67 };
     68 
     69 db_expr_t
     70 db_get_value(addr, size, is_signed)
     71 	db_addr_t	addr;
     72 	register int	size;
     73 	boolean_t	is_signed;
     74 {
     75 	char		data[sizeof(int)];
     76 	register db_expr_t value;
     77 	register int	i;
     78 
     79 	db_read_bytes(addr, size, data);
     80 
     81 	value = 0;
     82 #if	BYTE_MSF
     83 	for (i = 0; i < size; i++)
     84 #else	/* BYTE_LSF */
     85 	for (i = size - 1; i >= 0; i--)
     86 #endif
     87 	{
     88 	    value = (value << 8) + (data[i] & 0xFF);
     89 	}
     90 
     91 	if (size < 4) {
     92 	    if (is_signed && (value & db_extend[size]) != 0)
     93 		value |= db_extend[size];
     94 	}
     95 	return (value);
     96 }
     97 
     98 void
     99 db_put_value(addr, size, value)
    100 	db_addr_t	addr;
    101 	register int	size;
    102 	register db_expr_t value;
    103 {
    104 	char		data[sizeof(int)];
    105 	register int	i;
    106 
    107 #if	BYTE_MSF
    108 	for (i = size - 1; i >= 0; i--)
    109 #else	/* BYTE_LSF */
    110 	for (i = 0; i < size; i++)
    111 #endif
    112 	{
    113 	    data[i] = value & 0xFF;
    114 	    value >>= 8;
    115 	}
    116 
    117 	db_write_bytes(addr, size, data);
    118 }
    119 
    120