struct buf *
blk_get(blk_nr_t blk_nr)
{
struct buf *bufp;
repeat:
if ((bufp = btable_get(blk_nr))) { // requested block in the table
if (bufp->locked) {
;// Wait until it become unlocked
goto repeat;
}
bufp->locked = 1;
bfree_rm(bufp); // it has to be in the bfree
return bufp;
}
if (!(bufp = bfree_any_take())) { /*
A buffer is never locked across syscalls, thefore the kernel
can guarantee that a buffer will eventually become available */
;// Wait until a free buffer is available
goto repeat;
}
// the taken buffer is not now in the free buffer pool
bufp->locked = 1;
btable_rm(bufp); // it could be in the btable
bufp->blk_nr = blk_nr;
bufp->valid = 0;
btable_ins(bufp);
return bufp;
}
static inline bool check(uint32_t *ptable, uint32_t x, uint64_t *p_k)
{
int k;
int n = 0;
bool ok = false;
*p_k = 0;
for(k = 1; ; k++) {
n = 2 * k * k;
if(n > x) break;
if(btable_get(ptable, x - n)) {
ok = true;
*p_k = k;
break;
}
}
return ok;
}
int main(int argc, char **argv)
{
int n_in = 0;
int x_in = 0;
for (int c; (c = getopt(argc, argv, "n:x:")) != -1;) {
switch(c) {
case 'n':
n_in = atoi(optarg);
break;
case 'x':
x_in = atoi(optarg);
break;
}
}
uint64_t result = 0;
uint32_t pents[1000000] = {};
vector(int) *vpents = vector_new(int, 100);
int i, j, n = 0, m = 0;
for(i = 1; ; i++) {
n = pentagonal(i);
if(n > 32000000) break;
btable_set(pents, n);
vector_pushback(vpents, n);
m = n;
}
int cur, tgt, sum, diff;
uint32_t d = 0xFFFFFFFF;
for(i = 1; i < vpents->idx - 1; i++) {
cur = vpents->buf[i];
if(cur - vpents->buf[i - 1] > d) {
ICHECK;
break;
}
for(j = 0 ;j < i; j++) {
tgt = vpents->buf[j];
sum = cur + tgt;
diff = cur - tgt;
//printf("%d %d %d %d\n", tgt, cur, sum, diff);
if(sum <= n &&
btable_get(pents, sum) &&
btable_get(pents, diff)) {
printf("%d %d %d %d\n", tgt, cur, sum, diff);
d = min(d, diff);
}
}
}
vector_delete(vpents);
DUMPL(result = d);
return 0;
}
