DosOpen - Example Code

This example reads to a physical disk using the raw file system and DosListIO.

#define  INCL_ERRORS
#define  INCL_DOS
#define  INCL_NOPMAPI
#include <os2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <bsedev.h>
#include "listio.h"

#define   EightK   8*1024
#define   FourK   4*1024
#define   LISTIO_NUM 1000
#define   PAGE_RAND_MAX 100

CHAR  Buf[EightK];
LISTIO ListIO[LISTIO_NUM];
ULONG seed = 1;
ULONG page_rand(void);

int main (VOID)

{
   CHAR  *BufAligned;
   ULONG  rc;
   ULONG  Loop = LISTIO_NUM,
          i, j;
   ULONG  Action, Actual;
   HFILE  hFile;

   /* Make sure buffer is page aligned */

   BufAligned = (UCHAR *)(((LONG)Buf + FourK) & 0xFFFFF000);

   /* Open a raw file system disk */

   rc = DosOpen((PSZ)"\\\\.\\Physical_Disk2",
                &hFile,
                &Action,
                0L,
                FILE_NORMAL,
                OPEN_ACTION_OPEN_IF_EXISTS,
                OPEN_SHARE_DENYNONE | OPEN_ACCESS_READWRITE,
                0L);

   if (rc != NO_ERROR) {
      printf("DosOpen error:  rc = %u\n", rc);
      return(1);
   } /* if */
   /*************************************/
   /* Perform Random READ using DosRead */
   /*************************************/

   for(i = 0; i < Loop ; i++) { /* Loop for Random Read */
      rc = DosSetFilePtr(hFile,  /* file's handle */
                         page_rand()*FourK, /* offset */
                         FILE_BEGIN, /* from beginning of file */
                         &Actual);

      if (rc != NO_ERROR) {
         printf("DosSetFilePtr error:  rc = %u\n", rc);
         return(1);
      } /* if */

      rc = DosRead( hFile,  /* file's handle */
                    BufAligned,  /* buffer pointer */
                    FourK,   /* size to read */
                    &Actual);

      if (rc != NO_ERROR) {
         printf("DosRead error:  rc = %u\n", rc);
         return(1);
      } /* if */

   } /* for i */
   /****************************************/
   /* Perform Random Read using DosListIO  */
   /****************************************/

   for (i = 0; i < Loop; i++) {
      ListIO[i].hFile = hFile;
      ListIO[i].CmdFlag = LISTIO_READ | FILE_BEGIN;
      ListIO[i].Offset = page_rand()*FourK;
      ListIO[i].pBuffer = BufAligned;
      ListIO[i].NumBytes = FourK;
   } /* for i */

   rc = DosListIO( LISTIO_UNORDERED, /* unordered mode */
                   Loop,    /* number of reads */
                   ListIO);   /* array of control blocks */

   if (rc != NO_ERROR) {
      printf("DosListIO error:  rc = %u\n", rc);

      for (i = 0; i < Loop; i++) {
         if ((ListIO[i].Actual != FourK) ||
             (ListIO[i].RetCode != NO_ERROR)) {
            printf("DosListIO error:  i = %d, Actual = %d, RetCode = %u\n",
     I, ListIO[i].Actual, ListIO[i].RetCode);
         } /* if */
      } /* for i */
      return(1);
   } /* if */
   /* Close file */

   rc = DosClose(hFile);

   if (rc != NO_ERROR) {
      printf("DosClose error:  rc = %u\n", rc);
      return(1);
   }

   return(NO_ERROR);

}

/********************************************************/
/*                                                      */
/* FUNCTION: page_rand                               */
/*                                                      */
/* DESCRIPTION: Generate random number in range         */
/*              [0,PAGE_RAND_MAX-1]           */
/*                                                      */
/********************************************************/

ULONG page_rand()

{
   seed = seed * 1103515245 + 12345;
   return(((ULONG)(seed/(2*PAGE_RAND_MAX)) % PAGE_RAND_MAX));

}