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// +build ignore
package main
import (
. "github.com/mmcloughlin/avo/build"
. "github.com/mmcloughlin/avo/operand"
)
func main() {
TEXT("Sum", NOSPLIT, "func(xs []uint64) uint64")
Doc("Sum returns the sum of the elements in xs.")
ptr := Load(Param("xs").Base(), GP64())
n := Load(Param("xs").Len(), GP64())
Comment("Initialize sum register to zero.")
s := GP64()
XORQ(s, s)
Label("loop")
Comment("Loop until zero bytes remain.")
CMPQ(n, Imm(0))
JE(LabelRef("done"))
Comment("Load from pointer and add to running sum.")
ADDQ(Mem{Base: ptr}, s)
Comment("Advance pointer, decrement byte count.")
ADDQ(Imm(8), ptr)
DECQ(n)
JMP(LabelRef("loop"))
Label("done")
Comment("Store sum to return value.")
Store(s, ReturnIndex(0))
RET()
Generate()
}
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