metrohash-64
MetroHash checksum

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metrohash-128

Vocabulary
checksums.metrohash

Class description
MetroHash 64-bit checksum algorithm.

Definition

IN: checksums.metrohash

TUPLE: metrohash-64 seed ;

Methods

USING: accessors alien.c-types checksums checksums.metrohash
checksums.metrohash.private combinators grouping kernel math
math.bitwise sequences ;

M:: metrohash-64 checksum-bytes ( bytes checksum -- value )
    3603962101 :> k0 2729050939 :> k1 1654206401 :> k2 817650473
    :> k3 checksum seed>> :> seed bytes length :> len len dup 32
    mod - :> len/32 len dup 16 mod - :> len/16 len dup 8 mod -
    :> len/8 len dup 4 mod - :> len/4 len dup 2 mod -
    :> len/2 seed k2 W+ k0 W*
    :> h h h h h :> ( v0! v1! v2! v3! ) len 32 >= [
        0 len/32 bytes uint64_t native-mapper 4 <groups> [
            first4 {
                [ k0 W* v0 W+ -29 bitroll-64 v2 W+ v0! ]
                [ k1 W* v1 W+ -29 bitroll-64 v3 W+ v1! ]
                [ k2 W* v2 W+ -29 bitroll-64 v0 W+ v2! ]
                [ k3 W* v3 W+ -29 bitroll-64 v1 W+ v3! ]
            } spread
        ] each v0 v3 W+ k0 W* v1 W+ -37 bitroll-64 k1 W*
        v2 bitxor v2! v1 v2 W+ k1 W* v0 W+ -37 bitroll-64 k0 W*
        v3 bitxor v3! v0 v2 W+ k0 W* v3 W+ -37 bitroll-64 k1 W*
        v0 bitxor v0! v1 v3 W+ k1 W* v2 W+ -37 bitroll-64 k0 W*
        v1 bitxor v1! v0 v1 bitxor h W+ v0!
    ] when len/32 len/16 bytes uint64_t native-mapper [
        first2
        [ k2 W* v0 W+ -29 bitroll-64 k3 W* v1! ]
        [ k2 W* v0 W+ -29 bitroll-64 k3 W* v2! ] bi* v1 k0 W*
        -21 bitroll-64 v2 W+ v1 bitxor v1! v2 k3 W*
        -21 bitroll-64 v1 W+ v2 bitxor v2! v2 v0 W+ v0!
    ] unless-empty len/16 len/8 bytes uint64_t native-mapper [
        first k3 W* v0 W+ v0! v0 -55 bitroll-64 k1 W* v0 bitxor
        v0!
    ] unless-empty len/8 len/4 bytes uint32_t native-mapper [
        first k3 W* v0 W+ v0! v0 -26 bitroll-64 k1 W* v0 bitxor
        v0!
    ] unless-empty len/4 len/2 bytes uint16_t native-mapper [
        first k3 W* v0 W+ v0! v0 -48 bitroll-64 k1 W* v0 bitxor
        v0!
    ] unless-empty bytes len/2 tail-slice [
        first k3 W* v0 W+ v0! v0 -37 bitroll-64 k1 W* v0 bitxor
        v0!
    ] unless-empty v0 -28 bitroll-64 v0 bitxor v0! ~11 more~ ;