Category : C Source Code
Archive   : INTRLIB1.ZIP
Filename : EMS.C

 
Output of file : EMS.C contained in archive : INTRLIB1.ZIP
/******************************************************************************
* EMS - expand memory support routines. *
* *
* Written by Gershon Elber, Dec. 1990 *
*******************************************************************************
* History: *
* 9 Dec 90 - Version 1.0 by Gershon Elber. *
******************************************************************************/

#include
#include
#include
#include "intr_loc.h"
#include "intr_ems.h"

/* #define DEBUG_EMS */

#define EMS_DEVICE_NAME "EMMXXXX0"

#define EMS_INT_NUM 0x67

#define EMS_SEGMENT 0x41
#define EMS_ALLOC 0x43
#define EMS_MAP 0x44
#define EMS_FREE 0x45

static unsigned int Segment = 0;

/******************************************************************************
* Returns TRUE iff EMS has been detected. *
******************************************************************************/
IntrBType EMSDetected(void)
{
char *p = (char *) getvect(EMS_INT_NUM);

if (p == NULL) return FALSE;

p = MK_FP(FP_SEG(p), 10); /* Get pointer to device name. */

if (strncmp(p, EMS_DEVICE_NAME, 8) != 0) return FALSE;

Segment = EMSSegment();

return TRUE;
}

/******************************************************************************
* Returns the segment of the base EMS address in the system, 0 if error. *
******************************************************************************/
unsigned int EMSSegment(void)
{
union REGS regs;

regs.h.ah = EMS_SEGMENT;

int86(EMS_INT_NUM, ®s, ®s);

if (regs.h.ah != 0) return 0;

return regs.x.bx;
}

/******************************************************************************
* EMS alloc routine. Returns EMS handle if succesfull, 0 if failed. *
******************************************************************************/
int EMSAlloc(int NumPages)
{
union REGS regs;

regs.x.bx = NumPages;
regs.h.ah = EMS_ALLOC;

int86(EMS_INT_NUM, ®s, ®s);

if (regs.h.ah != 0) return 0;

return regs.x.dx;
}

/******************************************************************************
* EMS mapping routine. The specified page number in the given EMS handle is *
* mapped to the specified physical page. *
* Returns a pointer to physical address. *
******************************************************************************/
void *EMSMap(int EMSHandle, int LogicPageNum, int PhysicPageNum)
{
union REGS regs;

regs.x.bx = LogicPageNum;
regs.x.dx = EMSHandle;
regs.h.al = PhysicPageNum;
regs.h.ah = EMS_MAP;

int86(EMS_INT_NUM, ®s, ®s);

if (regs.h.ah != 0) return NULL;

return MK_FP(Segment + 0x0400 * PhysicPageNum, 0x0000);
}

/******************************************************************************
* EMS free routine. Frees the EMS handle. *
******************************************************************************/
void EMSFree(int EMSHandle)
{
union REGS regs;

regs.x.dx = EMSHandle;
regs.h.ah = EMS_FREE;

int86(EMS_INT_NUM, ®s, ®s);
}

#ifdef DEBUG_EMS

/******************************************************************************
* Simple tests for the above routines. *
******************************************************************************/
void main(void)
{
int Handle1, Handle2;
void *p1, *p2;

if (EMSDetected())
fprintf(stderr, "EMS driver detected.\n");
else {
fprintf(stderr, "EMS driver not found.\n");
exit(1);
}

if ((Handle1 = EMSAlloc(1)) > 0)
fprintf(stderr, "EMS alloc one page - got handle \#%d.\n", Handle1);
else {
fprintf(stderr, "EMS alloc failed.\n");
exit(2);
}

if ((p1 = EMSMap(Handle1, 0, 0)) != NULL)
fprintf(stderr, "EMS map one page - address %p.\n", p1);
else {
fprintf(stderr, "EMS map failed.\n");
exit(2);
}

if ((Handle2 = EMSAlloc(5)) > 0)
fprintf(stderr, "EMS alloc five page - got handle \#%d.\n", Handle2);
else {
fprintf(stderr, "EMS alloc failed.\n");
exit(2);
}

if ((p2 = EMSMap(Handle2, 0, 1)) != NULL)
fprintf(stderr, "EMS map one page - address %p.\n", p2);
else {
fprintf(stderr, "EMS map failed.\n");
exit(2);
}

EMSFree(Handle1);
EMSFree(Handle2);
}

#endif /* DEBUG_EMS */


  3 Responses to “Category : C Source Code
Archive   : INTRLIB1.ZIP
Filename : EMS.C
”

  1. Daniel says:
    January 27, 2013 at 3:59 pm

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    March 18, 2014 at 4:57 pm

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