/* 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
#include
#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;
}