metrohash-128
MetroHash checksum

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metrohash-64

Vocabulary
checksums.metrohash

Class description
MetroHash 128-bit checksum algorithm.

Definition

IN: checksums.metrohash

TUPLE: metrohash-128 seed ;

Methods

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

M:: metrohash-128 checksum-bytes ( bytes checksum -- value )
    3359281633 :> k0 2252921819 :> k1 2078195771 :> k2 794325157
    :> 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 k0 W- k3 W* :> v0! seed k1 W+ k2 W*
    :> v1! seed k0 W+ k2 W* :> v2! seed k1 W- k3 W*
    :> 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+ -21 bitroll-64 k1 W*
        v2 bitxor v2! v1 v2 W+ k1 W* v0 W+ -21 bitroll-64 k0 W*
        v3 bitxor v3! v0 v2 W+ k0 W* v3 W+ -21 bitroll-64 k1 W*
        v0 bitxor v0! v1 v3 W+ k1 W* v2 W+ -21 bitroll-64 k0 W*
        v1 bitxor v1!
    ] when len/32 len/16 bytes uint64_t native-mapper [
        first2
        [ k2 W* v0 W+ -33 bitroll-64 k3 W* v0! ]
        [ k2 W* v1 W+ -33 bitroll-64 k3 W* v1! ] bi* v0 k2 W*
        v1 W+ -45 bitroll-64 k1 W* v0 bitxor v0! v1 k3 W* v0 W+
        -45 bitroll-64 k0 W* v1 bitxor v1!
    ] unless-empty len/16 len/8 bytes uint64_t native-mapper [
        first k2 W* v0 W+ -33 bitroll-64 k3 W* v0! v0 k2 W*
        v1 W+ -27 bitroll-64 k1 W* v0 bitxor v0!
    ] unless-empty len/8 len/4 bytes uint32_t native-mapper [
        first k2 W* v1 W+ -33 bitroll-64 k3 W* v1! v1 k3 W*
        v0 W+ -46 bitroll-64 k0 W* v1 bitxor v1!
    ] unless-empty len/4 len/2 bytes uint16_t native-mapper
    ~52 more~ ;