sys/ddb/db_access.c

/*
 * 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.
 *
 *      $Id$
 */

/*
 *      Author: David B. Golub, Carnegie Mellon University
 *      Date:   7/90
 */
#include "param.h"
#include "proc.h"
#include <machine/db_machdep.h>         /* type definitions */

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

extern void     db_read_bytes();        /* machine-dependent */
extern void     db_write_bytes();       /* machine-dependent */

int db_extend[] = {     /* table for sign-extending */
        0,
        0xFFFFFF80,
        0xFFFF8000,
        0xFF800000
};

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

        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 < 4) {
            if (is_signed && (value & db_extend[size]) != 0)
                value |= db_extend[size];
        }
        return (value);
}

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

#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);
}