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CodeBlocksPortable/WATCOM/samples/goodies/fileio.c

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/* Time buffered file I/O using a buffer of arbitrary size in low or
extended memory.
*/
#include <stdio.h>
#include <dos.h>
#include <malloc.h>
#include <time.h>
#include <stdlib.h>
int iobufsize = 32; /* in K */
void fatal (char *msg)
{
printf ("fileio: %s.\n", msg);
exit (1);
}
void main (int argc, char *argv[])
{
union REGS r;
FILE *fp;
register int i;
clock_t start, end;
char *outputbuf;
int do_low = 0;
/* Allocate an output buffer, in either low memory or extended memory,
as directed. Associate the buffer with the output file.
*/
while (argc-- > 1)
{
if ((argv[argc][0] == '-') || (argv[argc][0] == '/'))
{
if ((argv[argc][1] == 'l') || (argv[argc][1] == 'L'))
do_low = 1;
}
else
iobufsize = atoi(argv[argc]);
}
if (do_low)
{
r.x.eax = 0x100; /* DPMI allocate low memory */
r.x.ebx = iobufsize * (1024 / 16);
int386 (0x31, &r, &r);
if (r.w.cflag)
fatal ("couldn't allocate low memory");
outputbuf = (char *) (r.x.eax << 4);
}
else
{
if (! (outputbuf = malloc (iobufsize * 1024)))
fatal ("couldn't allocate extended memory");
}
printf ("Using %dK buffer in %s memory\n", iobufsize, do_low ? "low" : "extended");
if (! (fp = fopen ("bigfile", "w")))
fatal ("couldn't open output file");
if (setvbuf (fp, outputbuf, _IOFBF, iobufsize * 1024))
fatal ("couldn't buffer output file");
start = clock ();
for (i = 256 * 1024; i > 0; i--)
fputc ('x', fp); /* Write 256K 'x' characters */
fflush (fp); /* Commit to disk */
end = clock ();
if (ferror (fp))
fatal ("error writing output file");
fclose (fp);
remove ("bigfile");
printf ("elapsed time: %d clocks\n", (int) (end - start));
}