DoubleTap Evaluator

Prerequisites:

• gcc, clang, or another C compiler

• cmake>=3.17

Build instructions:

$ git clone https://github.com/themorlock/DoubleTapEvaluator.git
$ cd DoubleTapEvaluator
$ mkdir build
$ cd build
$ cmake -DCMAKE_BUILD_TYPE=Release ..
$ make
$ unzip ../data/DOUBLETAP_TABLES_COMPRESSED.zip -d ../data/ 

Benchmark:

Test	Evaluations/Second
All 5-Card Hands	292840676.1
All 6-Card Hands	221372489.5
All 7-Card Hands	235819763.9
Random 5-Card Hands	161421182.3
Random 6-Card Hands	167186224.5
Random 7-Card Hands	132665991.9

Usage:

#include "doubletap_eval.h"

int main()
{
    doubletap_5_initialize("DOUBLETAP_TABLE_5.dat");
    doubletap_6_initialize("DOUBLETAP_TABLE_6.dat");
    doubletap_7_initialize("DOUBLETAP_TABLE_7.dat");

    unsigned long long hand5 = 34376582145ULL;
    doubletap_eval_5_fast(hand5);
    
    unsigned long long hand6 = 34376582153ULL;
    doubletap_eval_6_fast(hand6);
    
    unsigned long long hand7 = 584132396041ULL;
    doubletap_eval_7_fast(hand7);

    return 0;
}

Algorithm:

Card	Value
2c	1
2d	2
2h	3
2s	4
3c	5
3d	6
3h	7
3s	8
4c	9
4d	10
4h	11
4s	12
5c	13
5d	14
5h	15
5s	16
6c	17
6d	18
6h	19
6s	20
7c	21
7d	22
7h	23
7s	24
8c	25
8d	26
8h	27
8s	28
9c	29
9d	30
9h	31
9s	32
tc	33
td	34
th	35
ts	36
jc	37
jd	38
jh	39
js	40
qc	41
qd	42
qh	43
qs	44
kc	45
kd	46
kh	47
ks	48
ac	49
ad	50
ah	51
as	52

Hand is represented as a 64-bit(unsigned long long) number:
000000000000000000000000100000000001000000010000010000000001
Hand = ts - 8c - 6c - 4h - 2c

Set-bit position from the right corresponds to the card.

Evaluator supports 5, 6, and 7 card hand evaluations.

First, the evaluator finds the positions of all the set bits. Next, it computes the lexicographical rank of the hand. Finally, it uses this rank to jump into the large lookup table. DoubleTap comes from the algorithm first jumping into a small lookup table to compute the lexicographical rank then jumping into the much larger lookup table.