/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 *
 * $FreeBSD: src/sys/ddb/db_access.c,v 1.15 1999/08/28 00:41:04 peter Exp $
 */

/*
 *      Author: David B. Golub, Carnegie Mellon University
 *      Date:   7/90
 */
#include <sys/param.h>
#include <machine/limits.h>

#include <ddb/ddb.h>
#include <ddb/db_access.h>

/*
 * Access unaligned data items on aligned (longword)
 * boundaries.
 */

#if LONG_BIT == 32

static unsigned db_extend[] = { /* table for sign-extending */
        0,
        0xFFFFFF80U,
        0xFFFF8000U,
        0xFF800000U
};

#else

static unsigned long db_extend[] = {    /* table for sign-extending */
        0,
        0xFFFFFFFFFFFFFF80LU,
        0xFFFFFFFFFFFF8000LU,
        0xFFFFFFFFFF800000LU,
        0xFFFFFFFF80000000LU,
        0xFFFFFF8000000000LU,
        0xFFFF800000000000LU,
        0xFF80000000000000LU
};

#endif

#ifndef BYTE_MSF
#define BYTE_MSF        0
#endif

db_expr_t
db_get_value(db_addr_t addr, int size, boolean_t is_signed)
{
        char    data[sizeof(long)];
        int     i;
        db_expr_t value;

        if (size > sizeof(long))
                size = sizeof(long);

        db_read_bytes(addr, size, data);

        value = 0;
#if     BYTE_MSF
        for (i = 0; i < size; i++)
#else   /* BYTE_LSF */
        for (i = size - 1; i >= 0; i--)
#endif
        {
                value = (value << 8) + (data[i] & 0xFF);
        }

        if (size < sizeof(long)) {
                if (is_signed && (value & db_extend[size]) != 0)
                        value |= db_extend[size];
        }
        return (value);
}

void
db_put_value(db_addr_t addr, int size, db_expr_t value)
{
        char    data[sizeof(long)];
        int     i;

        if (size > sizeof(long))
                size = sizeof(long);

#if     BYTE_MSF
        for (i = size - 1; i >= 0; i--)
#else   /* BYTE_LSF */
        for (i = 0; i < size; i++)
#endif
        {
                data[i] = value & 0xFF;
                value >>= 8;
        }

        db_write_bytes(addr, size, data);
}