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Annotation of Gnu-Mach/i386/util/i16/i16.h, revision 1.1.1.1

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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