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Annotation of sys/ddb/db_access.c, Revision 1.1

1.1     ! nbrk        1: /*     $OpenBSD: db_access.c,v 1.10 2007/03/15 17:10:22 miod Exp $     */
        !             2: /*     $NetBSD: db_access.c,v 1.8 1994/10/09 08:37:35 mycroft Exp $    */
        !             3:
        !             4: /*
        !             5:  * Mach Operating System
        !             6:  * Copyright (c) 1991,1990 Carnegie Mellon University
        !             7:  * All Rights Reserved.
        !             8:  *
        !             9:  * Permission to use, copy, modify and distribute this software and its
        !            10:  * documentation is hereby granted, provided that both the copyright
        !            11:  * notice and this permission notice appear in all copies of the
        !            12:  * software, derivative works or modified versions, and any portions
        !            13:  * thereof, and that both notices appear in supporting documentation.
        !            14:  *
        !            15:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
        !            16:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            17:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            18:  *
        !            19:  * Carnegie Mellon requests users of this software to return to
        !            20:  *
        !            21:  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
        !            22:  *  School of Computer Science
        !            23:  *  Carnegie Mellon University
        !            24:  *  Pittsburgh PA 15213-3890
        !            25:  *
        !            26:  * any improvements or extensions that they make and grant Carnegie the
        !            27:  * the rights to redistribute these changes.
        !            28:  *
        !            29:  *     Author: David B. Golub, Carnegie Mellon University
        !            30:  *     Date:   7/90
        !            31:  */
        !            32:
        !            33: #include <sys/param.h>
        !            34: #include <sys/proc.h>
        !            35:
        !            36: #include <uvm/uvm_extern.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: db_expr_t
        !            48: db_get_value(db_addr_t addr, size_t size, boolean_t is_signed)
        !            49: {
        !            50:        char data[sizeof(db_expr_t)];
        !            51:        db_expr_t value, extend;
        !            52:        int i;
        !            53:
        !            54: #ifdef DIAGNOSTIC
        !            55:        if (size > sizeof data)
        !            56:                size = sizeof data;
        !            57: #endif
        !            58:
        !            59:        db_read_bytes(addr, size, data);
        !            60:
        !            61:        value = 0;
        !            62:        extend = (~(db_expr_t)0) << (size * 8 - 1);
        !            63: #if BYTE_ORDER == LITTLE_ENDIAN
        !            64:        for (i = size - 1; i >= 0; i--)
        !            65: #else /* BYTE_ORDER == BIG_ENDIAN */
        !            66:        for (i = 0; i < size; i++)
        !            67: #endif /* BYTE_ORDER */
        !            68:                value = (value << 8) + (data[i] & 0xFF);
        !            69:
        !            70:        if (size < sizeof(db_expr_t) && is_signed && (value & extend))
        !            71:                value |= extend;
        !            72:        return (value);
        !            73: }
        !            74:
        !            75: void
        !            76: db_put_value(db_addr_t addr, size_t size, db_expr_t value)
        !            77: {
        !            78:        char data[sizeof(db_expr_t)];
        !            79:        int i;
        !            80:
        !            81: #ifdef DIAGNOSTIC
        !            82:        if (size > sizeof data)
        !            83:                size = sizeof data;
        !            84: #endif
        !            85:
        !            86: #if BYTE_ORDER == LITTLE_ENDIAN
        !            87:        for (i = 0; i < size; i++)
        !            88: #else /* BYTE_ORDER == BIG_ENDIAN */
        !            89:        for (i = size - 1; i >= 0; i--)
        !            90: #endif /* BYTE_ORDER */
        !            91:        {
        !            92:                data[i] = value & 0xff;
        !            93:                value >>= 8;
        !            94:        }
        !            95:
        !            96:        db_write_bytes(addr, size, data);
        !            97: }