emschk.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 74 行

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*
*                            Open Watcom Project
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//
// EMSCHK       : check for existence of EMS
//

#include "ftnstd.h"

#include <dos.h>

extern  int     _EMS_available(void);
extern  int     _EMS_get_number_of_pages(unsigned int *,unsigned int *);
extern  int     _EMS_map_memory(int,int,int);
extern  int     _EMS_allocate_memory(unsigned int,int *);
extern  int     _EMS_get_page_frame_segment(unsigned int *);

extern  unsigned int    EMSsegment;
extern  int             EMShandle;


void    InitEMS() {
//=================

// Initialize EMS.

    unsigned            total;
    unsigned            unallocated;
    unsigned            index;
    unsigned int        __FAR *p;

    EMSsegment = 0;
    if( _EMS_available() ) {
        _EMS_get_number_of_pages( &unallocated, &total );
        _EMS_get_page_frame_segment( &EMSsegment );
        if( _EMS_allocate_memory( 4, &EMShandle ) == 0 ) {
            for( index = 0; index < 4; ++index ) {
                _EMS_map_memory( EMShandle, index, index );
            }
            p = MK_FP( EMSsegment, 0 );     // point to memory
            *p = 0xFFFE;                    // set size to 64K - 2
        }
    }
}