SHLQ sketch

gistfile1.txt

package test

import (
	"fmt"
	"testing"
)

func TestThing(t *testing.T) {
	// a := uint64(0x07FFFFFFFFFFFFFFF)
	a := uint64(0x1FFF000000000000)
	b := uint64(0xFFFFFFFFFFFFFFFF)
	// 0000 0111 1111 1
	// 07F
	fmt.Printf("a %016x\n", a)
	fmt.Printf("b %016x\n", b)

	c := shlqTest(a, b)

	fmt.Printf("c %016x\n", c)
	fmt.Printf("d %016x\n", b<<13)

	c = (b << 13) | (a >> 51)
	fmt.Printf("e %016x\n", c)

	fmt.Printf("%x\n", ^uint32(1))
}


// +build amd64

// func shlqTest(lo, hi uint64) uint64
TEXT ·shlqTest(SB),$0
	MOVQ lo+0(FP), AX
	MOVQ hi+8(FP), BX
	SHLQ $13, AX, BX
	MOVQ BX, ret+16(FP)
	RET
  

package test

// go:noescape
func shlqTest(lo, hi uint64) uint64