99 lines
2.4 KiB
C
99 lines
2.4 KiB
C
#include "sort.h"
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/*
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Constant-time uint32_t sorting by Daniel J. Bernstein
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Source: https://sorting.cr.yp.to
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*/
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#define int32_MINMAX(a,b) \
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do { \
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int32 ab = (b) ^ (a); \
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int32 c = (b) - (a); \
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c ^= ab & (c ^ (b)); \
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c >>= 31; \
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c &= ab; \
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(a) ^= c; \
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(b) ^= c; \
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} while(0)
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static void int32_sort(int32 *x, size_t n) {
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size_t top, p, q, r, i, j;
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if (n < 2) {
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return;
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}
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top = 1;
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while (top < n - top) {
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top += top;
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}
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for (p = top; p >= 1; p >>= 1) {
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i = 0;
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while (i + 2 * p <= n) {
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for (j = i; j < i + p; ++j) {
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int32_MINMAX(x[j], x[j + p]);
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}
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i += 2 * p;
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}
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for (j = i; j < n - p; ++j) {
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int32_MINMAX(x[j], x[j + p]);
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}
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i = 0;
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j = 0;
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for (q = top; q > p; q >>= 1) {
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if (j != i) {
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for (;;) {
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if (j == n - q) {
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goto done;
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}
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int32 a = x[j + p];
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for (r = q; r > p; r >>= 1) {
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int32_MINMAX(a, x[j + r]);
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}
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x[j + p] = a;
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++j;
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if (j == i + p) {
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i += 2 * p;
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break;
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}
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}
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}
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while (i + p <= n - q) {
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for (j = i; j < i + p; ++j) {
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int32 a = x[j + p];
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for (r = q; r > p; r >>= 1) {
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int32_MINMAX(a, x[j + r]);
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}
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x[j + p] = a;
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}
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i += 2 * p;
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}
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/* now i + p > n - q */
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j = i;
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while (j < n - q) {
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int32 a = x[j + p];
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for (r = q; r > p; r >>= 1) {
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int32_MINMAX(a, x[j + r]);
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}
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x[j + p] = a;
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++j;
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}
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done:
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;
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}
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}
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}
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/* can save time by integrating xor loops with int32_sort */
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void PQCLEAN_LEDAKEMLT32_LEAKTIME_uint32_sort(uint32_t *x, size_t n) {
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size_t j;
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for (j = 0; j < n; ++j) {
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x[j] ^= 0x80000000;
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}
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int32_sort((int32_t *) x, n);
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for (j = 0; j < n; ++j) {
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x[j] ^= 0x80000000;
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}
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}
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