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/* hanoi solver for hanoi2 */
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
static int num_disks[3] =
{0, 0, 0};
static void
move_disk(int from, int to, int fd)
{
char buf[3];
assert(from != to);
num_disks[from]--;
num_disks[to]++;
#ifdef TEST_ENGINE
printf("%d --> %d\n", from, to);
#else
buf[0] = 'M';
buf[1] = (char) from;
buf[2] = (char) to;
if (3 != write(fd, buf, 3)) {
perror("can't write");
exit(1);
}
#endif
}
static void
move_disks(int from, int to, int n, int fd)
{
static int other_table[9] =
{-1, 2, 1, 2, -1, 0, 1, 0, -1};
int other;
assert(from != to);
other = other_table[from * 3 + to];
assert(other != -1);
if (n == 1) {
move_disk(from, to, fd);
} else {
move_disks(from, other, n - 1, fd);
move_disk(from, to, fd);
move_disks(other, to, n - 1, fd);
}
}
void
engine(int *args)
{
num_disks[0] = args[0];
for (;;) {
move_disks(0, 2, args[0], args[1]);
move_disks(2, 0, args[0], args[1]);
}
}
#ifdef TEST_ENGINE
int
main(int argc, char *argv[])
{
int engine_args[2];
if (argc > 1) {
engine_args[0] = atoi(argv[1]);
}
engine_args[1] = 1;
engine(n, engine_args);
return 0; /* ANSI C requires main to return int. */
}
#endif
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