--- /dev/null
+/* Licensed under GPL v2+ - see LICENSE file for details */
+
+#include <ccan/endian/endian.h>
+
+#include "siphash.h"
+
+typedef uint64_t u64;
+
+enum sip_index { A=0, B=2, C=1, D=3, E=4 };
+
+#define rol(x,l) (((x) << (l)) | ((x) >> (64-(l))))
+
+#define SIP_HALF_ROUND(a,b,c,d,L1,L2) \
+ (a) += (b); \
+ (c) += (d); \
+ (b) = (a) ^ rol((b),L1); \
+ (d) = (c) ^ rol((d),L2); \
+ (a) = rol((a),32);
+
+#define SIP_ROUND(W) \
+ do { \
+ SIP_HALF_ROUND((W)[A], (W)[B], (W)[C], (W)[D], 13, 16); \
+ SIP_HALF_ROUND((W)[C], (W)[B], (W)[A], (W)[D], 17, 21); \
+ } while(0)
+
+/* Load a 64-bit word as little endian */
+#define W64(S,I) (le64_to_cpu(*((u64 *)(S) + (I))))
+
+static void siphash_init(u64 v[5], const unsigned char key[16])
+{
+ v[A] = W64(key, 0) ^ UINT64_C(0x736f6d6570736575);
+ v[B] = W64(key, 1) ^ UINT64_C(0x646f72616e646f6d);
+ v[C] = W64(key, 0) ^ UINT64_C(0x6c7967656e657261);
+ v[D] = W64(key, 1) ^ UINT64_C(0x7465646279746573);
+ v[E] = 0; /* message continuation */
+}
+
+/* Load the last 0-7 bytes of `in` and put in len & 255 */
+static void siphash_epilogue(u64 *m, const void *in, size_t len)
+{
+ in = (char *)in + (len & ~7);
+ *m = (u64)(len & 255) << 56;
+ switch (len & 7) {
+ case 7: *m |= (u64)*((unsigned char *)in+6) << 48;
+ case 6: *m |= (u64)*((unsigned char *)in+5) << 40;
+ case 5: *m |= (u64)*((unsigned char *)in+4) << 32;
+ case 4: *m |= (u64)*((unsigned char *)in+3) << 24;
+ case 3: *m |= (u64)*((unsigned char *)in+2) << 16;
+ case 2: *m |= (u64)*((unsigned char *)in+1) << 8;
+ case 1: *m |= (u64)*((unsigned char *)in+0);
+ case 0: ;
+ }
+}
+
+u64 siphash_2_4(const void *in, size_t len, const unsigned char key[16])
+{
+ u64 v[5];
+ size_t j;
+
+ siphash_init(v, key);
+
+ for (j = 0; j < len/8; j++) {
+ v[E] = W64(in, j);
+ v[D] ^= v[E];
+ SIP_ROUND(v);
+ SIP_ROUND(v);
+ v[A] ^= v[E];
+ }
+ siphash_epilogue(&v[E], in, len);
+
+ v[D] ^= v[E];
+ SIP_ROUND(v);
+ SIP_ROUND(v);
+ v[A] ^= v[E];
+
+ /* Finalize */
+ v[C] ^= 0xff;
+ SIP_ROUND(v);
+ SIP_ROUND(v);
+ SIP_ROUND(v);
+ SIP_ROUND(v);
+
+ return v[A]^v[B]^v[C]^v[D];
+}
+