// Equihash solver
// Copyright (c) 2016 John Tromp

// Equihash presents the following problem
//
// Fix N, K, such that N is a multiple of K+1
// Let integer n = N/(K+1), and view N-bit words
// as having K+1 "digits" of n bits each
// Fix M = 2^{n+1} N-bit hashes H_0, ... , H_{M-1}
// as outputs of a hash function applied to an (n+1)-bit index
//
// Problem: find a binary tree on 2^K distinct indices,
// for which the exclusive-or of leaf hashes is all 0s
// Additionally, it should satisfy the Wagner conditions:
// 1) for each height i subtree, the exclusive-or
// of its 2^i leaf hashes starts with i*n 0 bits,
// 2) the leftmost leaf of any left subtree is less
// than the leftmost leaf of the corresponding right subtree
//
// The algorithm below solves this by storing trees
// as a directed acyclic graph of K layers
// The n digit bits are split into
// n-RESTBITS bucket bits and RESTBITS leftover bits
// Each layer i, consisting of height i subtrees
// whose xor starts with i*n 0s, is partitioned into
// 2^{n-RESTBITS} buckets according to the next n-RESTBITS
// in the xor
// Within each bucket, trees whose xor match in the
// next RESTBITS bits are combined to produce trees
// in the next layer
// To eliminate trees with duplicated indices,
// we simply test if the last 32 bits of the xor are 0,
// and if so, assume that this is due to index duplication
// In practice this works very well to avoid bucket overflow
// and produces negligible false positives

#include "equi.h"
#include <stdio.h>
#include <pthread.h>
#include <assert.h>

#if defined __builtin_bswap32 && defined __LITTLE_ENDIAN
#undef htobe32
#define htobe32(x) __builtin_bswap32(x)
#elif defined __APPLE__
#undef htobe32
#define htobe32(x) OSSwapHostToBigInt32(x)
#endif

// u32 already defined in equi.h
typedef uint16_t u16;
typedef uint64_t u64;

// rquired for avoiding multio-threading race conflicts
#ifdef ATOMIC
#include <atomic>
typedef std::atomic<u32> au32;
#else
typedef u32 au32;
#endif

#ifndef RESTBITS
#define RESTBITS	8
#endif

// 2_log of number of buckets
#define BUCKBITS (DIGITBITS-RESTBITS)

// by default buckets have a capacity of twice their expected size
// but this factor reduced it accordingly
#ifndef SAVEMEM
#if RESTBITS == 4
// can't save memory in such small buckets
#define SAVEMEM 1
#elif RESTBITS >= 8
// an expected size of at least 512 has such relatively small
// standard deviation that we can reduce capacity with negligible discarding
// this value reduces (200,9) memory to under 144MB
#define SAVEMEM 9/14
#endif
#endif

// number of buckets
static const u32 NBUCKETS = 1<<BUCKBITS;
// corresponding bucket mask
static const u32 BUCKMASK = NBUCKETS-1;
// 2_log of number of slots per bucket
static const u32 SLOTBITS = RESTBITS+1+1;
// default bucket capacity
static const u32 SLOTRANGE = 1<<SLOTBITS;
// corresponding SLOTBITS mask
static const u32 SLOTMASK = SLOTRANGE-1;
// most significat bit in SLOTMASK
static const u32 SLOTMSB = 1<<(SLOTBITS-1);
// number of slots per bucket
static const u32 NSLOTS = SLOTRANGE * SAVEMEM;
// number of per-xhash slots
static const u32 XFULL = 16;
// number of possible values of RESTBITS bits
static const u32 NRESTS = 1<<RESTBITS;
// number of blocks of hashes extracted from single 512 bit blake2b output
static const u32 NBLOCKS = (NHASHES+HASHESPERBLAKE-1)/HASHESPERBLAKE;
// more than 8 solutions are rare (less than one in 100000 runs)
static const u32 MAXSOLS = 8;

// tree node identifying its children as two different slots in
// a bucket on previous layer with matching rest bits (x-tra hash)
struct tree {
  // formerly i had these bitfields
  // unsigned bucketid : BUCKBITS;
  // unsigned slotid0  : SLOTBITS;
  // unsigned slotid1 : SLOTBITS;
  // but these were poorly optimized by the compiler
  // so now we do things "manually"
  u32 bid_s0_s1;

  // constructor for height 0 trees stores index instead
  tree(const u32 idx) {
    bid_s0_s1 = idx;
  }
  tree(const u32 bid, const u32 s0, const u32 s1) {
// SLOTDIFF saves 1 bit by encoding the distance between
// the two slots modulo SLOTRANGE instead, and picking
// slotid0 such that this distance is at most SLOTRANGE/2
// the extra branching involved gives noticeable slowdown
#ifdef SLOTDIFF
    u32 ds10 = (s1 - s0) & SLOTMASK;
    if (ds10 & SLOTMSB) {
      bid_s0_s1 = (((bid << SLOTBITS) | s1) << (SLOTBITS-1)) | (SLOTMASK & ~ds10);
    } else {
      bid_s0_s1 = (((bid << SLOTBITS) | s0) << (SLOTBITS-1)) | (ds10 - 1);
    }
#else
    bid_s0_s1 = (((bid << SLOTBITS) | s0) << SLOTBITS) | s1;
#endif
  }
  // retrieve hash index from tree(const u32 idx) constructor
  u32 getindex() const {
    return bid_s0_s1;
  }
  // retrieve bucket index
  u32 bucketid() const {
#ifdef SLOTDIFF
    return bid_s0_s1 >> (2 * SLOTBITS - 1);
#else
    return bid_s0_s1 >> (2 * SLOTBITS);
#endif
  }
  // retrieve first slot index
  u32 slotid0() const {
#ifdef SLOTDIFF
    return (bid_s0_s1 >> (SLOTBITS-1)) & SLOTMASK;
#else
    return (bid_s0_s1 >> SLOTBITS) & SLOTMASK;
#endif
  }
  // retrieve second slot index
  u32 slotid1() const {
#ifdef SLOTDIFF
    return (slotid0() + 1 + (bid_s0_s1 & (SLOTMASK>>1))) & SLOTMASK;
#else
    return bid_s0_s1 & SLOTMASK;
#endif
  }
};

// each bucket slot occupies a variable number of hash/tree units,
// all but the last of which hold the xor over all leaf hashes,
// or what's left of it after stripping the initial i*n 0s
// the last unit holds the tree node itself
// the hash is sometimes accessed 32 bits at a time (word)
// and sometimes 8 bits at a time (bytes)
union htunit {
  tree tag;
  u32 word;
  uchar bytes[sizeof(u32)];
};

#define WORDS(bits)	((bits + 31) / 32)
#define HASHWORDS0 WORDS(WN - DIGITBITS + RESTBITS)
#define HASHWORDS1 WORDS(WN - 2*DIGITBITS + RESTBITS)

// A slot is up to HASHWORDS0 hash units followed by a tag
typedef htunit slot0[HASHWORDS0+1];
typedef htunit slot1[HASHWORDS1+1];
// a bucket is NSLOTS treenodes
typedef slot0 bucket0[NSLOTS];
typedef slot1 bucket1[NSLOTS];
// the N-bit hash consists of K+1 n-bit "digits"
// each of which corresponds to a layer of NBUCKETS buckets
typedef bucket0 digit0[NBUCKETS];
typedef bucket1 digit1[NBUCKETS];
typedef au32 bsizes[NBUCKETS];

// The algorithm proceeds in K+1 rounds, one for each digit
// All data is stored in two heaps,
// heap0 of type digit0, and heap1 of type digit1
// The following table shows the layout of these heaps
// in each round, which is an optimized version
// of xenoncat's fixed memory layout, avoiding any waste
// Each line shows only a single slot, which is actually
// replicated NSLOTS * NBUCKETS times
//
//             heap0         heap1
// round  hashes   tree   hashes tree
// 0      A A A A A A 0   . . . . . .
// 1      A A A A A A 0   B B B B B 1
// 2      C C C C C 2 0   B B B B B 1
// 3      C C C C C 2 0   D D D D 3 1
// 4      E E E E 4 2 0   D D D D 3 1
// 5      E E E E 4 2 0   F F F 5 3 1
// 6      G G 6 . 4 2 0   F F F 5 3 1
// 7      G G 6 . 4 2 0   H H 7 5 3 1
// 8      I 8 6 . 4 2 0   H H 7 5 3 1
//
// Round 0 generates hashes and stores them in the buckets
// of heap0 according to the initial n-RESTBITS bits
// These hashes are denoted A above and followed by the
// tree tag denoted 0
// In round 1 we combine each pair of slots in the same bucket
// with matching RESTBITS of digit 0 and store the resulting
// 1-tree in heap1 with its xor hash denoted B
// Upon finishing round 1, the A space is no longer needed,
// and is re-used in round 2 to store both the shorter C hashes,
// and their tree tags denoted 2
// Continuing in this manner, each round reads buckets from one
// heap, and writes buckets in the other heap.
// In the final round K, all pairs leading to 0 xors are identified
// and their leafs recovered through the DAG of tree nodes

// convenience function
u32 min(const u32 a, const u32 b) {
  return a < b ? a : b;
}

// size (in bytes) of hash in round 0 <= r < WK
u32 hashsize(const u32 r) {
  const u32 hashbits = WN - (r+1) * DIGITBITS + RESTBITS;
  return (hashbits + 7) / 8;
}

// convert bytes into words,rounding up
u32 hashwords(u32 bytes) {
  return (bytes + 3) / 4;
}

// manages hash and tree data
struct htalloc {
  bucket0 *heap0;
  bucket1 *heap1;
  u32 alloced;
  htalloc() {
    alloced = 0;
  }
  void alloctrees() {
    assert(DIGITBITS >= 16); // ensures hashes shorten by 1 unit every 2 digits
    heap0 = (bucket0 *)alloc(NBUCKETS, sizeof(bucket0));
    heap1 = (bucket1 *)alloc(NBUCKETS, sizeof(bucket1));
  }
  void dealloctrees() {
    free(heap0);
    free(heap1);
  }
  void *alloc(const u32 n, const u32 sz) {
    void *mem  = calloc(n, sz);
    assert(mem);
    alloced += n * sz;
    return mem;
  }
};

struct equi {
  blake2b_state blake_ctx;
  htalloc hta;
  bsizes *nslots;
  proof *sols;
  au32 nsols;
  u32 nthreads;
  u32 xfull;
  u32 bfull;
  u32 hfull;
  pthread_barrier_t barry;
  equi(const u32 n_threads) {
    assert(sizeof(htunit) == 4);
    assert(WK&1); // assumed in candidate() calling indices1()
    nthreads = n_threads;
    const int err = pthread_barrier_init(&barry, NULL, nthreads);
    assert(!err);
    hta.alloctrees();
    nslots = (bsizes *)hta.alloc(2 * NBUCKETS, sizeof(au32));
    sols   =  (proof *)hta.alloc(MAXSOLS, sizeof(proof));
  }
  ~equi() {
    hta.dealloctrees();
    free(nslots);
    free(sols);
  }
  void setheadernonce(const char *headernonce, const u32 len) {
    setheader(&blake_ctx, headernonce);
    memset(nslots, 0, NBUCKETS * sizeof(au32)); // only nslots[0] needs zeroing
    nsols = xfull = bfull = hfull = 0;
  }
  u32 getslot0(const u32 bucketi) {
#ifdef ATOMIC
    return std::atomic_fetch_add_explicit(&nslots[0][bucketi], 1U, std::memory_order_relaxed);
#else
    return nslots[0][bucketi]++;
#endif
  }
  u32 getslot1(const u32 bucketi) {
#ifdef ATOMIC
    return std::atomic_fetch_add_explicit(&nslots[1][bucketi], 1U, std::memory_order_relaxed);
#else
    return nslots[1][bucketi]++;
#endif
  }
  u32 getnslots0(const u32 bid) {
    au32 &nslot = nslots[0][bid];
    const u32 n = min(nslot, NSLOTS);
    nslot = 0;
    return n;
  }
  u32 getnslots1(const u32 bid) {
    au32 &nslot = nslots[1][bid];
    const u32 n = min(nslot, NSLOTS);
    nslot = 0;
    return n;
  }
#ifdef MERGESORT
  // if merged != 0, mergesort indices and return true if dupe found
  // if merged == 0, order indices as in Wagner condition
  bool orderindices(u32 *indices, u32 size, u32 *merged) {
    if (merged) {
      u32 i = 0, j = 0, k;
      for (k = 0; i<size && j<size; k++) {
        if (indices[i] == indices[size+j]) return true;
        merged[k] = indices[i] < indices[size+j] ? indices[i++] : indices[size+j++];
      }
      memcpy(merged+k, indices+i, (size-i) * sizeof(u32));
      memcpy(indices,  merged,    (size+j) * sizeof(u32));
      return false;
    } else {
      if (indices[0] > indices[size]) {
        for (u32 i=0; i < size; i++) {
          const u32 tmp = indices[i];
          indices[i] = indices[size+i];
          indices[size+i] = tmp;
        }
      }
      return false;
    }
  }
  // return true if dupe found
  bool listindices0(u32 r, const tree t, u32 *indices, u32 *merged) {
    if (r == 0) {
      *indices = t.getindex();
      return false;
    }
    const slot1 *buck = hta.heap1[t.bucketid()];
    const u32 size = 1 << --r;
    u32 *indices1 = indices + size;
    u32 tagi = hashwords(hashsize(r));
    return listindices1(r, buck[t.slotid0()][tagi].tag, indices,  merged)
        || listindices1(r, buck[t.slotid1()][tagi].tag, indices1, merged)
        || orderindices(indices, size, merged);
  }
  bool listindices1(u32 r, const tree t, u32 *indices, u32 *merged) {
    const slot0 *buck = hta.heap0[t.bucketid()];
    const u32 size = 1 << --r;
    u32 *indices1 = indices + size;
    u32 tagi = hashwords(hashsize(r));
    return listindices0(r, buck[t.slotid0()][tagi].tag, indices,  merged)
        || listindices0(r, buck[t.slotid1()][tagi].tag, indices1, merged)
        || orderindices(indices, size, merged);
  }
  void candidate(const tree t) {
    proof prf, merged;
    if (listindices1(WK, t, prf, merged)) return;
#ifdef ATOMIC
    u32 soli = std::atomic_fetch_add_explicit(&nsols, 1U, std::memory_order_relaxed);
#else
    u32 soli = nsols++;
#endif
    if (soli < MAXSOLS) listindices1(WK, t, sols[soli], 0);
  }
#else
  bool orderindices(u32 *indices, u32 size) {
    if (indices[0] > indices[size]) {
      for (u32 i=0; i < size; i++) {
        const u32 tmp = indices[i];
        indices[i] = indices[size+i];
        indices[size+i] = tmp;
      }
    }
    return false;
  }
  // if dupes != 0, list indices in arbitrary order and return true if dupe found
  // if dupes == 0, order indices as in Wagner condition
  bool listindices0(u32 r, const tree t, u32 *indices, u32 *dupes) {
    if (r == 0) {
      u32 idx = t.getindex();
      if (dupes) {
        u32 bin = idx & (PROOFSIZE-1);
        if (idx == dupes[bin]) return true;
        dupes[bin] = idx;
      }
      *indices = idx;
      return false;
    }
    const slot1 *buck = hta.heap1[t.bucketid()];
    const u32 size = 1 << --r;
    u32 tagi = hashwords(hashsize(r));
    return listindices1(r, buck[t.slotid0()][tagi].tag, indices,      dupes)
        || listindices1(r, buck[t.slotid1()][tagi].tag, indices+size, dupes)
        || (!dupes && orderindices(indices, size));
  }
  bool listindices1(u32 r, const tree t, u32 *indices, u32 *dupes) {
    const slot0 *buck = hta.heap0[t.bucketid()];
    const u32 size = 1 << --r;
    u32 tagi = hashwords(hashsize(r));
    return listindices0(r, buck[t.slotid0()][tagi].tag, indices,      dupes)
        || listindices0(r, buck[t.slotid1()][tagi].tag, indices+size, dupes)
        || (!dupes && orderindices(indices, size));
  }
  void candidate(const tree t) {
    proof prf, dupes;
    memset(dupes, 0xffff, sizeof(proof));
    if (listindices1(WK, t, prf, dupes)) return; // assume WK odd
    qsort(prf, PROOFSIZE, sizeof(u32), &compu32);
    for (u32 i=1; i<PROOFSIZE; i++) if (prf[i] <= prf[i-1]) return;
#ifdef ATOMIC
    u32 soli = std::atomic_fetch_add_explicit(&nsols, 1U, std::memory_order_relaxed);
#else
    u32 soli = nsols++;
#endif
    if (soli < MAXSOLS) listindices1(WK, t, sols[soli], 0); // assume WK odd
  }
#endif
  void showbsizes(u32 r) {
    printf(" x%d b%d h%d\n", xfull, bfull, hfull);
    xfull = bfull = hfull = 0;
#if defined(HIST) || defined(SPARK) || defined(LOGSPARK)
    u32 binsizes[65];
    memset(binsizes, 0, 65 * sizeof(u32));
    for (u32 bucketid = 0; bucketid < NBUCKETS; bucketid++) {
      u32 bsize = min(nslots[r&1][bucketid], NSLOTS) >> (SLOTBITS-6);
      binsizes[bsize]++;
    }
    for (u32 i=0; i < 65; i++) {
#ifdef HIST
      printf(" %d:%d", i, binsizes[i]);
#else
#ifdef SPARK
      u32 sparks = binsizes[i] / SPARKSCALE;
#else
      u32 sparks = 0;
      for (u32 bs = binsizes[i]; bs; bs >>= 1) sparks++;
      sparks = sparks * 7 / SPARKSCALE;
#endif
      printf("\342\226%c", '\201' + sparks);
#endif
    }
    printf("\n");
#endif
    printf("Digit %d", r+1);
  }

  struct htlayout {
    htalloc hta;
    u32 prevhtunits;
    u32 nexthtunits;
    u32 dunits;
    u32 prevbo;
  
    htlayout(equi *eq, u32 r): hta(eq->hta), prevhtunits(0), dunits(0) {
      u32 nexthashbytes = hashsize(r);
      nexthtunits = hashwords(nexthashbytes);
      prevbo = 0;
      if (r) {
        u32 prevhashbytes = hashsize(r-1);
        prevhtunits = hashwords(prevhashbytes);
        prevbo = prevhtunits * sizeof(htunit) - prevhashbytes; // 0-3
        dunits = prevhtunits - nexthtunits;
      }
    }
    u32 getxhash0(const htunit* slot) const {
#if WN == 200 && RESTBITS == 4
      return slot->bytes[prevbo] >> 4;
#elif WN == 200 && RESTBITS == 8
      return (slot->bytes[prevbo] & 0xf) << 4 | slot->bytes[prevbo+1] >> 4;
#elif WN == 144 && RESTBITS == 4
      return slot->bytes[prevbo] & 0xf;
#else
#error non implemented
#endif
    }
    u32 getxhash1(const htunit* slot) const {
#if WN == 200 && RESTBITS == 4
      return slot->bytes[prevbo] & 0xf;
#elif WN == 200 && RESTBITS == 8
      return slot->bytes[prevbo];
#elif WN == 144 && RESTBITS == 4
      return slot->bytes[prevbo] & 0xf;
#else
#error non implemented
#endif
    }
    bool equal(const htunit *hash0, const htunit *hash1) const {
      return hash0[prevhtunits-1].word == hash1[prevhtunits-1].word;
    }
  };

  struct collisiondata {
#ifdef XBITMAP
#if NSLOTS > 64
#error cant use XBITMAP with more than 64 slots
#endif
    u64 xhashmap[NRESTS];
    u64 xmap;
#else
#if RESTBITS <= 6
    typedef uchar xslot;
#else
    typedef u16 xslot;
#endif
    xslot nxhashslots[NRESTS];
    xslot xhashslots[NRESTS][XFULL];
    xslot *xx;
    u32 n0;
    u32 n1;
#endif
    u32 s0;

    void clear() {
#ifdef XBITMAP
      memset(xhashmap, 0, NRESTS * sizeof(u64));
#else
      memset(nxhashslots, 0, NRESTS * sizeof(xslot));
#endif
    }
    bool addslot(u32 s1, u32 xh) {
#ifdef XBITMAP
      xmap = xhashmap[xh];
      xhashmap[xh] |= (u64)1 << s1;
      s0 = -1;
      return true;
#else
      n1 = (u32)nxhashslots[xh]++;
      if (n1 >= XFULL)
        return false;
      xx = xhashslots[xh];
      xx[n1] = s1;
      n0 = 0;
      return true;
#endif
    }
    bool nextcollision() const {
#ifdef XBITMAP
      return xmap != 0;
#else
      return n0 < n1;
#endif
    }
    u32 slot() {
#ifdef XBITMAP
      const u32 ffs = __builtin_ffsll(xmap);
      s0 += ffs; xmap >>= ffs;
      return s0;
#else
      return (u32)xx[n0++];
#endif
    }
  };

  void digit0(const u32 id) {
    uchar hash[HASHOUT];
    blake2b_state state0 = blake_ctx;
    htlayout htl(this, 0);
    const u32 hashbytes = hashsize(0);
    for (u32 block = id; block < NBLOCKS; block += nthreads) {
      blake2b_state state = state0;
      u32 leb = htole32(block);
      blake2b_update(&state, (uchar *)&leb, sizeof(u32));
      blake2b_final(&state, hash, HASHOUT);
      for (u32 i = 0; i<HASHESPERBLAKE; i++) {
        const uchar *ph = hash + i * WN/8;
#if BUCKBITS == 12 && RESTBITS == 8
        const u32 bucketid = ((u32)ph[0] << 4) | ph[1] >> 4;
#elif BUCKBITS == 16 && RESTBITS == 4
        const u32 bucketid = ((u32)ph[0] << 8) | ph[1];
#elif BUCKBITS == 20 && RESTBITS == 4
        const u32 bucketid = ((((u32)ph[0] << 8) | ph[1]) << 4) | ph[2] >> 4;
#elif BUCKBITS == 12 && RESTBITS == 4
        const u32 bucketid = ((u32)ph[0] << 4) | ph[1] >> 4;
        const u32 xhash = ph[1] & 0xf;
#else
#error not implemented
#endif
        const u32 slot = getslot0(bucketid);
        if (slot >= NSLOTS) {
          bfull++;
          continue;
        }
        htunit *s = hta.heap0[bucketid][slot] + htl.nexthtunits;
        memcpy(s->bytes-hashbytes, ph+WN/8-hashbytes, hashbytes);
        s->tag = tree(block * HASHESPERBLAKE + i);
      }
    }
  }
  
  void digitodd(const u32 r, const u32 id) {
    htlayout htl(this, r);
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = htl.hta.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htl.getxhash0(slot1))) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (htl.equal(slot0, slot1)) {
            hfull++;
            continue;
          }
          u32 xorbucketid;
          const uchar *bytes0 = slot0->bytes, *bytes1 = slot1->bytes;
#if WN == 200 && BUCKBITS == 12 && RESTBITS == 8
          xorbucketid = (((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) & 0xf) << 8)
                             | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2]);
#elif WN == 144 && BUCKBITS == 20 && RESTBITS == 4
          xorbucketid = ((((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) << 8)
                              | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2])) << 4)
                              | (bytes0[htl.prevbo+3] ^ bytes1[htl.prevbo+3]) >> 4;
#elif WN == 96 && BUCKBITS == 12 && RESTBITS == 4
          xorbucketid = ((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) << 4)
                            | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2]) >> 4;
#else
#error not implemented
#endif
          const u32 xorslot = getslot1(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = htl.hta.heap1[xorbucketid][xorslot];
          for (u32 i=htl.dunits; i < htl.prevhtunits; i++)
            xs++->word = slot0[i].word ^ slot1[i].word;
          xs->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  
  void digiteven(const u32 r, const u32 id) {
    htlayout htl(this, r);
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot1 *buck = htl.hta.heap1[bucketid];
      u32 bsize   = getnslots1(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htl.getxhash1(slot1))) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (htl.equal(slot0, slot1)) {
            hfull++;
            continue;
          }
          u32 xorbucketid;
          const uchar *bytes0 = slot0->bytes, *bytes1 = slot1->bytes;
#if WN == 200 && BUCKBITS == 12 && RESTBITS == 8
          xorbucketid = ((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) << 4)
                            | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2]) >> 4;
#elif WN == 144 && BUCKBITS == 20 && RESTBITS == 4
          xorbucketid = ((((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) << 8)
                              | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2])) << 4)
                              | (bytes0[htl.prevbo+3] ^ bytes1[htl.prevbo+3]) >> 4;
#elif WN == 96 && BUCKBITS == 12 && RESTBITS == 4
          xorbucketid = ((u32)(bytes0[htl.prevbo+1] ^ bytes1[htl.prevbo+1]) << 4)
                            | (bytes0[htl.prevbo+2] ^ bytes1[htl.prevbo+2]) >> 4;
#else
#error not implemented
#endif
          const u32 xorslot = getslot0(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = htl.hta.heap0[xorbucketid][xorslot];
          for (u32 i=htl.dunits; i < htl.prevhtunits; i++)
            xs++->word = slot0[i].word ^ slot1[i].word;
          xs->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  
  void digit1(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = heaps.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htobe32(slot1->word) >> 20 & 0xff)) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[5].word == slot1[5].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0->word ^ slot1->word) >> 8 & BUCKMASK;
          const u32 xorslot = getslot1(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          u64 *x  = (u64 *)heaps.heap1[xorbucketid][xorslot];
          u64 *x0 = (u64 *)slot0, *x1 = (u64 *)slot1;
          *x++ = x0[0] ^ x1[0];
          *x++ = x0[1] ^ x1[1];
          *x++ = x0[2] ^ x1[2];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit2(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot1 *buck = heaps.heap1[bucketid];
      u32 bsize   = getnslots1(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, slot1->bytes[3])) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[5].word == slot1[5].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0[1].word ^ slot1[1].word) >> 20;
          const u32 xorslot = getslot0(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = heaps.heap0[xorbucketid][xorslot];
          xs++->word = slot0[1].word ^ slot1[1].word;
          u64 *x = (u64 *)xs, *x0 = (u64 *)slot0, *x1 = (u64 *)slot1;
          *x++ = x0[1] ^ x1[1];
          *x++ = x0[2] ^ x1[2];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit3(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = heaps.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htobe32(slot1->word) >> 12 & 0xff)) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[4].word == slot1[4].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0[0].word ^ slot1[0].word) & BUCKMASK;
          const u32 xorslot = getslot1(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          u64 *x  = (u64 *)heaps.heap1[xorbucketid][xorslot];
          u64 *x0 = (u64 *)(slot0+1), *x1 = (u64 *)(slot1+1);
          *x++ = x0[0] ^ x1[0];
          *x++ = x0[1] ^ x1[1];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit4(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot1 *buck = heaps.heap1[bucketid];
      u32 bsize   = getnslots1(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, slot1->bytes[0])) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[3].word == slot1[3].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0[0].word ^ slot1[0].word) >> 12 & BUCKMASK;
          const u32 xorslot = getslot0(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          u64 *x  = (u64 *)heaps.heap0[xorbucketid][xorslot];
          u64 *x0 = (u64 *)slot0, *x1 = (u64 *)slot1;
          *x++ = x0[0] ^ x1[0];
          *x++ = x0[1] ^ x1[1];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit5(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = heaps.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htobe32(slot1->word) >> 4 & 0xff)) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[3].word == slot1[3].word) {
            hfull++;
            continue;
          }
          u32 xor1 = slot0[1].word ^ slot1[1].word;
          u32 xorbucketid = (((u32)(slot0->bytes[3] ^ slot1->bytes[3]) & 0xf)
                               << 8) | (xor1 & 0xff);
          const u32 xorslot = getslot1(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = heaps.heap1[xorbucketid][xorslot];
          xs++->word = xor1;
          u64 *x = (u64 *)xs, *x0 = (u64 *)slot0, *x1 = (u64 *)slot1;
          *x++ = x0[1] ^ x1[1];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit6(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot1 *buck = heaps.heap1[bucketid];
      u32 bsize   = getnslots1(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, slot1->bytes[1])) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[2].word == slot1[2].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0[0].word ^ slot1[0].word) >> 4 & BUCKMASK;
          const u32 xorslot = getslot0(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = heaps.heap0[xorbucketid][xorslot];
          xs++->word = slot0[0].word ^ slot1[0].word;
          u64 *x = (u64 *)xs, *x0 = (u64 *)(slot0+1), *x1 = (u64 *)(slot1+1);
          *x++ = x0[0] ^ x1[0];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit7(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = heaps.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, (slot1->bytes[3] & 0xf) << 4 | slot1->bytes[4] >> 4)) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          if (slot0[2].word == slot1[2].word) {
            hfull++;
            continue;
          }
          u32 xorbucketid = htobe32(slot0[1].word ^ slot1[1].word) >> 16 & BUCKMASK;
          const u32 xorslot = getslot1(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          u64 *x  = (u64 *)heaps.heap1[xorbucketid][xorslot];
          u64 *x0 = (u64 *)(slot0+1), *x1 = (u64 *)(slot1+1);
          *x++ = x0[0] ^ x1[0];
          ((htunit *)x)->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  void digit8(const u32 id) {
    htalloc heaps = hta;
    collisiondata cd;
    for (u32 bucketid=id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot1 *buck = heaps.heap1[bucketid];
      u32 bsize   = getnslots1(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, slot1->bytes[2])) {
          xfull++;
          continue;
        }
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          const htunit *slot0 = buck[s0];
          u32 xor1 = slot0[1].word ^ slot1[1].word;
          if (!xor1) {
            hfull++;
            continue;
          }
          u32 xorbucketid = ((u32)(slot0->bytes[3] ^ slot1->bytes[3]) << 4)
                          | (xor1 >> 4 & 0xf);
          const u32 xorslot = getslot0(xorbucketid);
          if (xorslot >= NSLOTS) {
            bfull++;
            continue;
          }
          htunit *xs = heaps.heap0[xorbucketid][xorslot];
          xs++->word = xor1;
          xs->tag = tree(bucketid, s0, s1);
        }
      }
    }
  }
  
  void digitK(const u32 id) {
    collisiondata cd;
    htlayout htl(this, WK);
    u32 nc = 0;
    for (u32 bucketid = id; bucketid < NBUCKETS; bucketid += nthreads) {
      cd.clear();
      slot0 *buck = htl.hta.heap0[bucketid];
      u32 bsize   = getnslots0(bucketid);
      for (u32 s1 = 0; s1 < bsize; s1++) {
        const htunit *slot1 = buck[s1];
        if (!cd.addslot(s1, htl.getxhash0(slot1))) // assume WK odd
          continue;
        for (; cd.nextcollision(); ) {
          const u32 s0 = cd.slot();
          if (htl.equal(buck[s0], slot1)) { // EASY OPTIMIZE
            candidate(tree(bucketid, s0, s1));
            nc++;
          }
        }
      }
    }
    printf(" %d candidates ", nc);
  }
};

typedef struct {
  u32 id;
  pthread_t thread;
  equi *eq;
} thread_ctx;

void barrier(pthread_barrier_t *barry) {
  const int rc = pthread_barrier_wait(barry);
  if (rc != 0 && rc != PTHREAD_BARRIER_SERIAL_THREAD) {
    printf("Could not wait on barrier\n");
    pthread_exit(NULL);
  }
}

void *worker(void *vp) {
  thread_ctx *tp = (thread_ctx *)vp;
  equi *eq = tp->eq;

  if (tp->id == 0) printf("Digit 0");
  eq->digit0(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(0);
  barrier(&eq->barry);
#if WN == 200 && WK == 9 && RESTBITS == 8 && defined UNROLL
  eq->digit1(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(1);
  barrier(&eq->barry);
  eq->digit2(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(2);
  barrier(&eq->barry);
  eq->digit3(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(3);
  barrier(&eq->barry);
  eq->digit4(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(4);
  barrier(&eq->barry);
  eq->digit5(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(5);
  barrier(&eq->barry);
  eq->digit6(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(6);
  barrier(&eq->barry);
  eq->digit7(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(7);
  barrier(&eq->barry);
  eq->digit8(tp->id);
  barrier(&eq->barry);
  if (tp->id == 0) eq->showbsizes(8);
  barrier(&eq->barry);
#else
  for (u32 r = 1; r < WK; r++) {
    r&1 ? eq->digitodd(r, tp->id) : eq->digiteven(r, tp->id);
    barrier(&eq->barry);
    if (tp->id == 0) eq->showbsizes(r);
    barrier(&eq->barry);
  }
#endif
  eq->digitK(tp->id);
  pthread_exit(NULL);
  return 0;
}