Thursday, 05 August 2021
64-bit Kogge-Stone Move Generator - Vector-Based
I switched to 64-bit Dumb7Fill move gen to keep things simple and spare some registers, but maybe it is of interest for some folks, the generalized and vectorized Kogge-Stone move generation*:
the shifts and wraps:
// move generator costants
__constant ulong4 shift4 = (ulong4)( 9, 1, 7, 8);
// wraps for kogge stone shifts
__constant ulong4 wraps4[2] =
{
// wraps shift left
(ulong4)(
0xfefefefefefefe00, // <<9
0xfefefefefefefefe, // <<1
0x7f7f7f7f7f7f7f00, // <<7
0xffffffffffffff00 // <<8
),
// wraps shift right
(ulong4)(
0x007f7f7f7f7f7f7f, // >>9
0x7f7f7f7f7f7f7f7f, // >>1
0x00fefefefefefefe, // >>7
0x00ffffffffffffff // >>8
)
};
the precalculated attack-tables:
// precomputed attack tables for move generation and square in check
__constant Bitboard AttackTablesPawnPushes[2*64] =
{
// white pawn pushes
0x100,0x200,0x400,0x800,0x1000,0x2000,0x4000,0x8000,0x1010000,0x2020000,0x4040000,0x8080000,0x10100000,0x20200000,0x40400000,0x80800000,0x1000000,0x2000000,0x4000000,0x8000000,0x10000000,0x20000000,0x40000000,0x80000000,0x100000000,0x200000000,0x400000000,0x800000000,0x1000000000,0x2000000000,0x4000000000,0x8000000000,0x10000000000,0x20000000000,0x40000000000,0x80000000000,0x100000000000,0x200000000000,0x400000000000,0x800000000000,0x1000000000000,0x2000000000000,0x4000000000000,0x8000000000000,0x10000000000000,0x20000000000000,0x40000000000000,0x80000000000000,0x100000000000000,0x200000000000000,0x400000000000000,0x800000000000000,0x1000000000000000,0x2000000000000000,0x4000000000000000,0x8000000000000000,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,
// black pawn pushes
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80,0x100,0x200,0x400,0x800,0x1000,0x2000,0x4000,0x8000,0x10000,0x20000,0x40000,0x80000,0x100000,0x200000,0x400000,0x800000,0x1000000,0x2000000,0x4000000,0x8000000,0x10000000,0x20000000,0x40000000,0x80000000,0x100000000,0x200000000,0x400000000,0x800000000,0x1000000000,0x2000000000,0x4000000000,0x8000000000,0x10100000000,0x20200000000,0x40400000000,0x80800000000,0x101000000000,0x202000000000,0x404000000000,0x808000000000,0x1000000000000,0x2000000000000,0x4000000000000,0x8000000000000,0x10000000000000,0x20000000000000,0x40000000000000,0x80000000000000
};
// piece attack tables
__constant Bitboard AttackTables[7*64] =
{
// white pawn
0x200,0x500,0xa00,0x1400,0x2800,0x5000,0xa000,0x4000,0x20000,0x50000,0xa0000,0x140000,0x280000,0x500000,0xa00000,0x400000,0x2000000,0x5000000,0xa000000,0x14000000,0x28000000,0x50000000,0xa0000000,0x40000000,0x200000000,0x500000000,0xa00000000,0x1400000000,0x2800000000,0x5000000000,0xa000000000,0x4000000000,0x20000000000,0x50000000000,0xa0000000000,0x140000000000,0x280000000000,0x500000000000,0xa00000000000,0x400000000000,0x2000000000000,0x5000000000000,0xa000000000000,0x14000000000000,0x28000000000000,0x50000000000000,0xa0000000000000,0x40000000000000,0x200000000000000,0x500000000000000,0xa00000000000000,0x1400000000000000,0x2800000000000000,0x5000000000000000,0xa000000000000000,0x4000000000000000,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,
// black pawn
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x2,0x5,0xa,0x14,0x28,0x50,0xa0,0x40,0x200,0x500,0xa00,0x1400,0x2800,0x5000,0xa000,0x4000,0x20000,0x50000,0xa0000,0x140000,0x280000,0x500000,0xa00000,0x400000,0x2000000,0x5000000,0xa000000,0x14000000,0x28000000,0x50000000,0xa0000000,0x40000000,0x200000000,0x500000000,0xa00000000,0x1400000000,0x2800000000,0x5000000000,0xa000000000,0x4000000000,0x20000000000,0x50000000000,0xa0000000000,0x140000000000,0x280000000000,0x500000000000,0xa00000000000,0x400000000000,0x2000000000000,0x5000000000000,0xa000000000000,0x14000000000000,0x28000000000000,0x50000000000000,0xa0000000000000,0x40000000000000,
// knight
0x20400,0x50800,0xa1100,0x142200,0x284400,0x508800,0xa01000,0x402000,0x2040004,0x5080008,0xa110011,0x14220022,0x28440044,0x50880088,0xa0100010,0x40200020,0x204000402,0x508000805,0xa1100110a,0x1422002214,0x2844004428,0x5088008850,0xa0100010a0,0x4020002040,0x20400040200,0x50800080500,0xa1100110a00,0x142200221400,0x284400442800,0x508800885000,0xa0100010a000,0x402000204000,0x2040004020000,0x5080008050000,0xa1100110a0000,0x14220022140000,0x28440044280000,0x50880088500000,0xa0100010a00000,0x40200020400000,0x204000402000000,0x508000805000000,0xa1100110a000000,0x1422002214000000,0x2844004428000000,0x5088008850000000,0xa0100010a0000000,0x4020002040000000,0x400040200000000,0x800080500000000,0x1100110a00000000,0x2200221400000000,0x4400442800000000,0x8800885000000000,0x100010a000000000,0x2000204000000000,0x4020000000000,0x8050000000000,0x110a0000000000,0x22140000000000,0x44280000000000,0x88500000000000,0x10a00000000000,0x20400000000000,
// king
0x302,0x705,0xe0a,0x1c14,0x3828,0x7050,0xe0a0,0xc040,0x30203,0x70507,0xe0a0e,0x1c141c,0x382838,0x705070,0xe0a0e0,0xc040c0,0x3020300,0x7050700,0xe0a0e00,0x1c141c00,0x38283800,0x70507000,0xe0a0e000,0xc040c000,0x302030000,0x705070000,0xe0a0e0000,0x1c141c0000,0x3828380000,0x7050700000,0xe0a0e00000,0xc040c00000,0x30203000000,0x70507000000,0xe0a0e000000,0x1c141c000000,0x382838000000,0x705070000000,0xe0a0e0000000,0xc040c0000000,0x3020300000000,0x7050700000000,0xe0a0e00000000,0x1c141c00000000,0x38283800000000,0x70507000000000,0xe0a0e000000000,0xc040c000000000,0x302030000000000,0x705070000000000,0xe0a0e0000000000,0x1c141c0000000000,0x3828380000000000,0x7050700000000000,0xe0a0e00000000000,0xc040c00000000000,0x203000000000000,0x507000000000000,0xa0e000000000000,0x141c000000000000,0x2838000000000000,0x5070000000000000,0xa0e0000000000000,0x40c0000000000000,
// bishop
0x8040201008040200,0x80402010080500,0x804020110a00,0x8041221400,0x182442800,0x10204885000,0x102040810a000,0x102040810204000,0x4020100804020002,0x8040201008050005,0x804020110a000a,0x804122140014,0x18244280028,0x1020488500050,0x102040810a000a0,0x204081020400040,0x2010080402000204,0x4020100805000508,0x804020110a000a11,0x80412214001422,0x1824428002844,0x102048850005088,0x2040810a000a010,0x408102040004020,0x1008040200020408,0x2010080500050810,0x4020110a000a1120,0x8041221400142241,0x182442800284482,0x204885000508804,0x40810a000a01008,0x810204000402010,0x804020002040810,0x1008050005081020,0x20110a000a112040,0x4122140014224180,0x8244280028448201,0x488500050880402,0x810a000a0100804,0x1020400040201008,0x402000204081020,0x805000508102040,0x110a000a11204080,0x2214001422418000,0x4428002844820100,0x8850005088040201,0x10a000a010080402,0x2040004020100804,0x200020408102040,0x500050810204080,0xa000a1120408000,0x1400142241800000,0x2800284482010000,0x5000508804020100,0xa000a01008040201,0x4000402010080402,0x2040810204080,0x5081020408000,0xa112040800000,0x14224180000000,0x28448201000000,0x50880402010000,0xa0100804020100,0x40201008040201,
// rook
0x1010101010101fe,0x2020202020202fd,0x4040404040404fb,0x8080808080808f7,0x10101010101010ef,0x20202020202020df,0x40404040404040bf,0x808080808080807f,0x10101010101fe01,0x20202020202fd02,0x40404040404fb04,0x80808080808f708,0x101010101010ef10,0x202020202020df20,0x404040404040bf40,0x8080808080807f80,0x101010101fe0101,0x202020202fd0202,0x404040404fb0404,0x808080808f70808,0x1010101010ef1010,0x2020202020df2020,0x4040404040bf4040,0x80808080807f8080,0x1010101fe010101,0x2020202fd020202,0x4040404fb040404,0x8080808f7080808,0x10101010ef101010,0x20202020df202020,0x40404040bf404040,0x808080807f808080,0x10101fe01010101,0x20202fd02020202,0x40404fb04040404,0x80808f708080808,0x101010ef10101010,0x202020df20202020,0x404040bf40404040,0x8080807f80808080,0x101fe0101010101,0x202fd0202020202,0x404fb0404040404,0x808f70808080808,0x1010ef1010101010,0x2020df2020202020,0x4040bf4040404040,0x80807f8080808080,0x1fe010101010101,0x2fd020202020202,0x4fb040404040404,0x8f7080808080808,0x10ef101010101010,0x20df202020202020,0x40bf404040404040,0x807f808080808080,0xfe01010101010101,0xfd02020202020202,0xfb04040404040404,0xf708080808080808,0xef10101010101010,0xdf20202020202020,0xbf40404040404040,0x7f80808080808080,
// queen
0x81412111090503fe,0x2824222120a07fd,0x404844424150efb,0x8080888492a1cf7,0x10101011925438ef,0x2020212224a870df,0x404142444850e0bf,0x8182848890a0c07f,0x412111090503fe03,0x824222120a07fd07,0x4844424150efb0e,0x80888492a1cf71c,0x101011925438ef38,0x20212224a870df70,0x4142444850e0bfe0,0x82848890a0c07fc0,0x2111090503fe0305,0x4222120a07fd070a,0x844424150efb0e15,0x888492a1cf71c2a,0x1011925438ef3854,0x212224a870df70a8,0x42444850e0bfe050,0x848890a0c07fc0a0,0x11090503fe030509,0x22120a07fd070a12,0x4424150efb0e1524,0x88492a1cf71c2a49,0x11925438ef385492,0x2224a870df70a824,0x444850e0bfe05048,0x8890a0c07fc0a090,0x90503fe03050911,0x120a07fd070a1222,0x24150efb0e152444,0x492a1cf71c2a4988,0x925438ef38549211,0x24a870df70a82422,0x4850e0bfe0504844,0x90a0c07fc0a09088,0x503fe0305091121,0xa07fd070a122242,0x150efb0e15244484,0x2a1cf71c2a498808,0x5438ef3854921110,0xa870df70a8242221,0x50e0bfe050484442,0xa0c07fc0a0908884,0x3fe030509112141,0x7fd070a12224282,0xefb0e1524448404,0x1cf71c2a49880808,0x38ef385492111010,0x70df70a824222120,0xe0bfe05048444241,0xc07fc0a090888482,0xfe03050911214181,0xfd070a1222428202,0xfb0e152444840404,0xf71c2a4988080808,0xef38549211101010,0xdf70a82422212020,0xbfe0504844424140,0x7fc0a09088848281,
};
for each piece do...with lid as square
pfrom = GETPIECE(board, lid);
color = GETCOLOR(pfrom);
// generator and propagator (piece and empty squares)
bbGen4 = (ulong4)bbBlockers&SETMASKBB(lid);
bbPro4 = (ulong4)(~bbBlockers);
// kogge stone shift left via ulong4 vector
bbPro4 &= wraps4[0];
bbGen4 |= bbPro4 & (bbGen4 << shift4);
bbPro4 &= (bbPro4 << shift4);
bbGen4 |= bbPro4 & (bbGen4 << 2*shift4);
bbPro4 &= (bbPro4 << 2*shift4);
bbGen4 |= bbPro4 & (bbGen4 << 4*shift4);
bbGen4 = wraps4[0] & (bbGen4 << shift4);
bbTemp = bbGen4.s0|bbGen4.s1|bbGen4.s2|bbGen4.s3;
// set generator and propagator (piece and empty squares)
bbGen4 = (ulong4)bbBlockers&SETMASKBB(lid);
bbPro4 = (ulong4)(~bbBlockers);
// kogge stone shift right via ulong4 vector
bbPro4 &= wraps4[1];
bbGen4 |= bbPro4 & (bbGen4 >> shift4);
bbPro4 &= (bbPro4 >> shift4);
bbGen4 |= bbPro4 & (bbGen4 >> 2*shift4);
bbPro4 &= (bbPro4 >> 2*shift4);
bbGen4 |= bbPro4 & (bbGen4 >> 4*shift4);
bbGen4 = wraps4[1] & (bbGen4 >> shift4);
bbTemp |= bbGen4.s0|bbGen4.s1|bbGen4.s2|bbGen4.s3;
// consider knights
bbTemp = (GETPTYPE(pfrom)==KNIGHT)?BBFULL:bbTemp;
// verify captures
n = (color==stm)?(s32)stm:(s32)!stm;
n = (GETPTYPE(pfrom)==PAWN)?n:GETPTYPE(pfrom);
bbMask = AttackTables[n*64+lid];
bbMoves = (color==stm)?(bbMask&bbTemp&bbOpp):(bbMask&bbTemp);
// verify non captures
bbMask = (GETPTYPE(pfrom)==PAWN)?(AttackTablesPawnPushes[stm*64+lid]):bbMask;
bbMoves|= (color==stm&&!qs)?(bbMask&bbTemp&~bbBlockers):BBEMPTY;
This code snippet covers all pieces and moves, except en-passant, castle-moves, pawn promotions, and is without a legality-check. A ulong4 vector is used to perform 4 shift-directions, in theory you can also use a ulong8 vector for 8 directions, but some compilers complained about the negative shift on an unsigned data-type.
*based on work by Steffan Westcott, as published on CPW:
https://www.chessprogramming.org/Kogge-Stone_Algorithm
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