59 lines
1.6 KiB
C
59 lines
1.6 KiB
C
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#include "sc25519.h"
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#include "index_heap.h"
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/* caller's responsibility to ensure hlen>=3 */
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void heap_init(unsigned long long *h, unsigned long long hlen, sc25519 *scalars)
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{
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h[0] = 0;
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unsigned long long i=1;
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while(i<hlen)
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heap_push(h, &i, i, scalars);
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}
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void heap_extend(unsigned long long *h, unsigned long long oldlen, unsigned long long newlen, sc25519 *scalars)
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{
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unsigned long long i=oldlen;
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while(i<newlen)
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heap_push(h, &i, i, scalars);
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}
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void heap_push(unsigned long long *h, unsigned long long *hlen, unsigned long long elem, sc25519 *scalars)
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{
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/* Move up towards the root */
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/* XXX: Check size of hlen, whether cast to signed value is ok */
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signed long long pos = *hlen;
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signed long long ppos = (pos-1)/2;
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unsigned long long t;
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h[*hlen] = elem;
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while(pos > 0)
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{
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/* if(sc25519_lt_vartime(&scalars[h[ppos]], &scalars[h[pos]])) */
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if(sc25519_lt(&scalars[h[ppos]], &scalars[h[pos]]))
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{
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t = h[ppos];
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h[ppos] = h[pos];
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h[pos] = t;
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pos = ppos;
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ppos = (pos-1)/2;
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}
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else break;
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}
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(*hlen)++;
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}
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/* Put the largest value in the heap in max1, the second largest in max2 */
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void heap_get2max(unsigned long long *h, unsigned long long *max1, unsigned long long *max2, sc25519 *scalars)
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{
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*max1 = h[0];
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*max2 = h[1];
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if(sc25519_lt(&scalars[h[1]],&scalars[h[2]]))
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*max2 = h[2];
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}
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/* After the root has been replaced, restore heap property */
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/* extern void heap_rootreplaced(unsigned long long *h, unsigned long long hlen, sc25519 *scalars);
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*/
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/* extern void heap_rootreplaced_shortscalars(unsigned long long *h, unsigned long long hlen, sc25519 *scalars);
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*/
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