Resizable hash table for Mark Firsts (∊)

This commit is contained in:
Marshall Lochbaum 2022-10-30 21:12:12 -04:00
parent 8a551ab5ce
commit 2e1b64e0ca

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@ -104,11 +104,62 @@ B memberOf_c1(B t, B x) {
if (lw == 4) { if (n<8) { BRUTE(16); } else { LOOKUP(16); } }
#undef LOOKUP
if (lw == 5) {
if (n<=32) { BRUTE(32); }
if (n<=12) { BRUTE(32); }
// Resizable hash table, fall back to radix lookup
u32* xp = (u32*)xv;
i8* rp; B r = m_i8arrv(&rp, n);
usz log = 64 - CLZ(n);
usz msl = (64 - CLZ(n+n/2)) + 1; if (msl>18) msl=18;
usz sh = 32 - (msl<14? msl : 14); // Shift to fit to table
usz sz = 1 << (32 - sh); // Initial size
usz msz = 1 << msl; // Max sz
usz b = 64; // Block size
// Resize or abort if more than 1/2^thresh collisions/element
#define THRESH sz==msz? 1 : sz>=(1<<13)? 2 : 3
usz thresh = THRESH;
// Filling e slots past the end requires e*(e+1)/2 collisions, so
// n entries with 1/2 each can fill <sqrt(n/4)
usz ext = n<=b? n : b + (1 << ((log-2)/2));
TALLOC(u32, hash0, msz+ext); u32* hash = hash0 + msz-sz;
u32 x0 = hash32(xp[0]); rp[0] = 1;
for (u64 i = 0; i < sz+ext; i++) hash[i] = x0;
usz cc = 0; // Collision counter
usz i=1; while (1) {
usz e = n-i>b? i+b : n;
for (; i < e; i++) {
u32 h = hash32(xp[i]); u32 j0 = h>>sh, j = j0; u32 k;
while (k=hash[j], k!=h & k!=x0) j++;
cc += j-j0;
hash[j] = h;
rp[i] = k != h;
}
if (i == n) break;
if (cc >= e>>thresh) {
if (sz == msz) break; // Abort
// Resize hash
usz m = 1 + (sz < msz/4);
sh -= m;
usz dif = sz; sz <<= m; dif = sz-dif;
hash -= dif;
usz j = 0;
for (; j < dif; j++) hash[j] = x0;
for (; j < sz + ext; j++) {
u32 h = hash[j]; if (h==x0) continue; hash[j] = x0;
u32 k = h>>sh; while (hash[k]!=x0) k++;
hash[k] = h;
}
thresh = THRESH;
}
}
#undef THRESH
TFREE(hash0);
if (i==n) { decG(x); return taga(cpyBitArr(r)); }
// Radix-assisted lookup
usz rx = 256, tn = 1<<16; // Radix; table length
u32* v0 = (u32*)xv;
i8* r0; B r = m_i8arrv(&r0, n);
i8* r0 = rp;
TALLOC(u8, alloc, 6*n+(4+(tn>3*n?tn:3*n)+(2*rx+1)*sizeof(usz)));
// timeline
@ -124,7 +175,7 @@ B memberOf_c1(B t, B x) {
u8 *tab= (u8 *)(r1); // tn [+] tab tn #####
RADIX_LOOKUP_32(1, =0)
return num_squeeze(r);
return taga(cpyBitArr(r));
}
#undef BRUTE