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Annotation of Gnu-Mach/i386/util/i16/i16.h, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Copyright (c) 1995-1994 The University of Utah and
        !             3:  * the Computer Systems Laboratory at the University of Utah (CSL).
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * Permission to use, copy, modify and distribute this software is hereby
        !             7:  * granted provided that (1) source code retains these copyright, permission,
        !             8:  * and disclaimer notices, and (2) redistributions including binaries
        !             9:  * reproduce the notices in supporting documentation, and (3) all advertising
        !            10:  * materials mentioning features or use of this software display the following
        !            11:  * acknowledgement: ``This product includes software developed by the
        !            12:  * Computer Systems Laboratory at the University of Utah.''
        !            13:  *
        !            14:  * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
        !            15:  * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
        !            16:  * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            17:  *
        !            18:  * CSL requests users of this software to return to [email protected] any
        !            19:  * improvements that they make and grant CSL redistribution rights.
        !            20:  *
        !            21:  *      Author: Bryan Ford, University of Utah CSL
        !            22:  */
        !            23: #ifndef _I386_I16_
        !            24: #define _I386_I16_
        !            25: 
        !            26: #include <mach/machine/code16.h>
        !            27: 
        !            28: #include "gdt.h"
        !            29: 
        !            30: 
        !            31: /* Macros to switch between 16-bit and 32-bit code
        !            32:    in the middle of a C function.
        !            33:    Be careful with these!  */
        !            34: #define i16_switch_to_32bit() asm volatile("
        !            35:                ljmp    %0,$1f
        !            36:                .code32
        !            37:        1:
        !            38:        " : : "i" (KERNEL_CS));
        !            39: #define switch_to_16bit() asm volatile("
        !            40:                ljmp    %0,$1f
        !            41:                .code16
        !            42:        1:
        !            43:        " : : "i" (KERNEL_16_CS));
        !            44: 
        !            45: 
        !            46: /* From within one type of code, execute 'stmt' in the other.
        !            47:    These are safer and harder to screw up with than the above macros.  */
        !            48: #define i16_do_32bit(stmt) \
        !            49:        ({      i16_switch_to_32bit(); \
        !            50:                { stmt; } \
        !            51:                switch_to_16bit(); })
        !            52: #define do_16bit(stmt) \
        !            53:        ({      switch_to_16bit(); \
        !            54:                { stmt; } \
        !            55:                i16_switch_to_32bit(); })
        !            56: 
        !            57: 
        !            58: #endif _I386_I16_

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