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