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Merge pull request #292 from Logan007/pearsonUpdate
pearson hashing: added optional 16-bit look-up table
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4a08411fe9
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@ -21,3 +21,5 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len);
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void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len);
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uint16_t pearson_hash_16 (const uint8_t *in, size_t len);
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void pearson_hash_init();
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@ -245,6 +245,8 @@ n2n_edge_t* edge_init(const tuntap_dev *dev, const n2n_edge_conf_t *conf, int *r
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eee->pending_peers = NULL;
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eee->sup_attempts = N2N_EDGE_SUP_ATTEMPTS;
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pearson_hash_init();
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if(eee->conf.compression == N2N_COMPRESSION_ID_LZO)
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if(lzo_init() != LZO_E_OK) {
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traceEvent(TRACE_ERROR, "LZO compression error");
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122
src/pearson.c
122
src/pearson.c
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@ -17,7 +17,6 @@
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*/
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// taken from https://github.com/Logan007/pearson
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// This is free and unencumbered software released into the public domain.
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#include <stddef.h>
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@ -25,6 +24,10 @@
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#include "pearson.h"
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// compile with 'LOW_MEM_FOOTPRINT' defined to make use of 256 byte look-up tabe only
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// otherwise, a 16-bit look-up table is used which allows considerably faster hashing
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// however, it needs to be generated by once calling pearson_hash_init() upfront
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// #define LOW_MEM_FOOTPRINT
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// table as in original paper "Fast Hashing of Variable-Length Text Strings" by Peter K. Pearson
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// as published in The Communications of the ACM Vol.33, No. 6 (June 1990), pp. 677-680.
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@ -67,11 +70,16 @@ static const uint8_t t[256] ={
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0xd8, 0x83, 0x59, 0x15, 0x1c, 0x85, 0x25, 0x99, 0x95, 0x50, 0xaa, 0x44, 0x06, 0xa9, 0xea, 0x97 }; */
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#ifndef LOW_MEM_FOOTPRINT
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static uint16_t t16[65536]; // 16-bit look-up table
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#endif
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#define ROR64(x,r) (((x)>>(r))|((x)<<(64-(r))))
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void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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size_t i;
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/* initial values - astonishingly, assembling using SHIFTs and ORs (in register)
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* works faster on well pipelined CPUs than loading the 64-bit value from memory.
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* however, there is one advantage to loading from memory: as we also store back to
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@ -79,10 +87,8 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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uint8_t upper[8] = { 0x0F, 0x0E, 0x0D, 0x0C, 0x0B, 0x0A, 0x09, 0x08 };
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uint8_t lower[8] = { 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00 };
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uint64_t *upper_hash_mask_ptr = (uint64_t*)&upper;
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uint64_t *lower_hash_mask_ptr = (uint64_t*)&lower;
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uint64_t upper_hash_mask = *upper_hash_mask_ptr;
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uint64_t lower_hash_mask = *lower_hash_mask_ptr;
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uint64_t upper_hash_mask = *(uint64_t*)&upper;
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uint64_t lower_hash_mask = *(uint64_t*)&lower;
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uint64_t high_upper_hash_mask = upper_hash_mask + 0x1010101010101010;
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uint64_t high_lower_hash_mask = lower_hash_mask + 0x1010101010101010;
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@ -90,7 +96,6 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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uint64_t lower_hash = 0;
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uint64_t high_upper_hash = 0;
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uint64_t high_lower_hash = 0;
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size_t i;
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for (i = 0; i < len; i++) {
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// broadcast the character, xor into hash, make them different permutations
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@ -104,8 +109,9 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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high_lower_hash ^= c ^ high_lower_hash_mask;
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// table lookup
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uint8_t x;
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uint64_t h = 0;
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#ifdef LOW_MEM_FOOTPRINT // 256 byte look-up table ----------
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uint8_t x;
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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@ -148,6 +154,35 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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x = high_lower_hash; x = t[x]; high_lower_hash >>= 8; h |= x; h=ROR64(h,8);
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x = high_lower_hash; x = t[x]; high_lower_hash >>= 8; h |= x; h=ROR64(h,8);
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high_lower_hash = h;
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#else // 16-bit look-up table -------------------------------
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uint16_t x;
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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upper_hash = h;
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h = 0;
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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lower_hash = h;
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h = 0;
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x = high_upper_hash; x = t16[x]; high_upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_upper_hash; x = t16[x]; high_upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_upper_hash; x = t16[x]; high_upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_upper_hash; x = t16[x]; high_upper_hash >>= 16; h |= x; h=ROR64(h,16);
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high_upper_hash = h;
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h = 0;
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x = high_lower_hash; x = t16[x]; high_lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_lower_hash; x = t16[x]; high_lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_lower_hash; x = t16[x]; high_lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = high_lower_hash; x = t16[x]; high_lower_hash >>= 16; h |= x; h=ROR64(h,16);
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high_lower_hash = h;
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#endif // LOW_MEM_FOOTPRINT ------
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}
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// store output
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uint64_t *o;
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@ -164,6 +199,7 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
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void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
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size_t i;
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/* initial values - astonishingly, assembling using SHIFTs and ORs (in register)
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* works faster on well pipelined CPUs than loading the 64-bit value from memory.
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* however, there is one advantage to loading from memory: as we also store back to
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@ -171,14 +207,11 @@ void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
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uint8_t upper[8] = { 0x0F, 0x0E, 0x0D, 0x0C, 0x0B, 0x0A, 0x09, 0x08 };
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uint8_t lower[8] = { 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00 };
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uint64_t *upper_hash_mask_ptr = (uint64_t*)&upper;
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uint64_t *lower_hash_mask_ptr = (uint64_t*)&lower;
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uint64_t upper_hash_mask = *upper_hash_mask_ptr;
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uint64_t lower_hash_mask = *lower_hash_mask_ptr;
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uint64_t upper_hash_mask = *(uint64_t*)&upper;
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uint64_t lower_hash_mask = *(uint64_t*)&lower;
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uint64_t upper_hash = 0;
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uint64_t lower_hash = 0;
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size_t i;
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for (i = 0; i < len; i++) {
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// broadcast the character, xor into hash, make them different permutations
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@ -189,8 +222,9 @@ void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
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upper_hash ^= c ^ upper_hash_mask;
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lower_hash ^= c ^ lower_hash_mask;
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// table lookup
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uint8_t x;
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uint64_t h = 0;
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#ifdef LOW_MEM_FOOTPRINT // 256 byte look-up table ----------
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uint8_t x;
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
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@ -210,7 +244,22 @@ void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
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x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
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x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
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x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
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lower_hash= h;
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#else // 16-bit look-up table -------------------------------
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uint16_t x;
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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x = upper_hash; x = t16[x]; upper_hash >>= 16; h |= x; h=ROR64(h,16);
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upper_hash = h;
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h = 0;
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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x = lower_hash; x = t16[x]; lower_hash >>= 16; h |= x; h=ROR64(h,16);
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lower_hash = h;
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#endif // LOW_MEM_FOOTPRINT ------
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}
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// store output
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uint64_t *o;
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@ -220,6 +269,38 @@ void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
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*o = lower_hash;
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}
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/* --- for later use ---
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// 32-bit hash: the return value has to be interpreted as uint32_t and
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// follows machine-specific endianess in memory
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uint32_t pearson_hash_32 (const uint8_t *in, size_t len) {
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size_t i;
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uint32_t hash = 0;
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uint32_t hash_mask = 0x03020100;
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for (i = 0; i < len; i++) {
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// broadcast the character, xor into hash, make them different permutations
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uint32_t c = (uint8_t)in[i];
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c |= c << 8;
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c |= c << 16;
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hash ^= c ^ hash_mask;
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// table lookup
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#ifdef LOW_MEM_FOOTPRINT
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uint32_t h = 0;
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uint8_t x;
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x = hash; x = t[x]; hash >>= 8; h |= x; h=ROR32(h,8);
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x = hash; x = t[x]; hash >>= 8; h |= x; h=ROR32(h,8);
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x = hash; x = t[x]; hash >>= 8; h |= x; h=ROR32(h,8);
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x = hash; x = t[x]; hash >>= 8; h |= x; h=ROR32(h,8);
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hash = h;
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#else
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hash = (t16[hash >> 16] << 16) + t16[(uint16_t)hash];
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#endif
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}
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// output
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return hash;
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} --- pearson_hash_32 for later use --- */
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// 16-bit hash: the return value has to be interpreted as uint16_t and
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// follows machine-specific endianess in memory
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@ -234,8 +315,23 @@ uint16_t pearson_hash_16 (const uint8_t *in, size_t len) {
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c |= c << 8;
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hash ^= c ^ hash_mask;
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// table lookup
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#ifdef LOW_MEM_FOOTPRINT
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hash = t[(uint8_t)hash] + (t[hash >> 8] << 8);
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#else
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hash = t16[hash];
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#endif
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}
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// output
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return hash;
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}
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void pearson_hash_init () {
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#ifndef LOW_MEM_FOOTPRINT
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size_t i;
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for (i = 0; i < 65536; i++)
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t16[i] = (t[i >> 8] << 8) + t[(uint8_t)i];
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#endif
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}
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3
src/sn.c
3
src/sn.c
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@ -50,6 +50,9 @@ static int init_sn(n2n_sn_t * sss) {
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#ifdef WIN32
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initWin32();
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#endif
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pearson_hash_init();
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memset(sss, 0, sizeof(n2n_sn_t));
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sss->daemon = 1; /* By defult run as a daemon. */
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@ -179,6 +179,9 @@ int sn_init(n2n_sn_t *sss)
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#ifdef WIN32
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initWin32();
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#endif
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pearson_hash_init();
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memset(sss, 0, sizeof(n2n_sn_t));
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sss->daemon = 1; /* By defult run as a daemon. */
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