Files
avo/examples/fnv1a
Michael McLoughlin 304c7425d2 build: add attributes argument to TEXT
Brings the TEXT() function signature closer to how the directive works
in assembly.

Also update almost all examples to use NOSPLIT.

Closes #11
2019-01-06 20:04:51 -08:00
..
2019-01-06 20:04:51 -08:00
2019-01-06 20:04:51 -08:00
2018-12-13 00:18:44 -08:00
2018-12-27 23:09:44 -08:00

fnv1a

FNV-1a in avo.

const (
	OffsetBasis = 0xcbf29ce484222325
	Prime       = 0x100000001b3
)

func main() {
	TEXT("Hash64", "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()
}