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//go:build ignore
// +build ignore
package main
import (
. "github.com/mmcloughlin/avo/build"
. "github.com/mmcloughlin/avo/operand"
. "github.com/mmcloughlin/avo/reg"
)
const (
OffsetBasis = 0xcbf29ce484222325
Prime = 0x100000001b3
)
func main() {
TEXT("Hash64", NOSPLIT, "func(data []byte) uint64")
Doc("Hash64 computes the FNV-1a hash of data.")
ptr := Load(Param("data").Base(), GP64())
n := Load(Param("data").Len(), GP64())
h := RAX
MOVQ(Imm(OffsetBasis), h)
p := GP64()
MOVQ(Imm(Prime), p)
Label("loop")
CMPQ(n, Imm(0))
JE(LabelRef("done"))
b := GP64()
MOVBQZX(Mem{Base: ptr}, b)
XORQ(b, h)
MULQ(p)
INCQ(ptr)
DECQ(n)
JMP(LabelRef("loop"))
Label("done")
Store(h, ReturnIndex(0))
RET()
Generate()
}
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