43 lines
893 B
C
43 lines
893 B
C
|
/* Reads a 128 kB file into static data and "sorts" the bytes in
|
||
|
|
it, using counting sort, a single-pass algorithm. The sorted
|
||
|
|
data is written back to the same file in-place. */
|
||
|
|
|
||
|
|
#include <debug.h>
|
||
|
|
#include <syscall.h>
|
||
|
|
#include "tests/lib.h"
|
||
|
|
#include "tests/main.h"
|
||
|
|
|
||
|
|
const char *test_name = "child-sort";
|
||
|
|
|
||
|
|
unsigned char buf[128 * 1024];
|
||
|
|
size_t histogram[256];
|
||
|
|
|
||
|
|
int
|
||
|
|
main (int argc UNUSED, char *argv[])
|
||
|
|
{
|
||
|
|
int handle;
|
||
|
|
unsigned char *p;
|
||
|
|
size_t size;
|
||
|
|
size_t i;
|
||
|
|
|
||
|
|
quiet = true;
|
||
|
|
|
||
|
|
CHECK ((handle = open (argv[1])) > 1, "open \"%s\"", argv[1]);
|
||
|
|
|
||
|
|
size = read (handle, buf, sizeof buf);
|
||
|
|
for (i = 0; i < size; i++)
|
||
|
|
histogram[buf[i]]++;
|
||
|
|
p = buf;
|
||
|
|
for (i = 0; i < sizeof histogram / sizeof *histogram; i++)
|
||
|
|
{
|
||
|
|
size_t j = histogram[i];
|
||
|
|
while (j-- > 0)
|
||
|
|
*p++ = i;
|
||
|
|
}
|
||
|
|
seek (handle, 0);
|
||
|
|
write (handle, buf, size);
|
||
|
|
close (handle);
|
||
|
|
|
||
|
|
return 123;
|
||
|
|
}
|