examples/geohash: first version

Adds helper for constants as DATA sections.

examples/geohash/asm.go

@@ -0,0 +1,40 @@
+// +build ignore
+
+package main
+
+import (
+	. "github.com/mmcloughlin/avo/build"
+	. "github.com/mmcloughlin/avo/operand"
+)
+
+func main() {
+	TEXT("EncodeInt", "func(lat, lng float64) uint64")
+	lat := Load(Param("lat"), Xv())
+	lng := Load(Param("lng"), Xv())
+
+	MULSD(ConstData("reciprocal180", F64(1/180.0)), lat)
+	onepointfive := ConstData("onepointfive", F64(1.5))
+	ADDSD(onepointfive, lat)
+
+	MULSD(ConstData("reciprocal360", F64(1/360.0)), lng)
+	ADDSD(onepointfive, lng)
+
+	lngi, lati := GP64v(), GP64v()
+	MOVQ(lat, lati)
+	SHRQ(U8(20), lati)
+	MOVQ(lng, lngi)
+	SHRQ(U8(20), lngi)
+
+	mask := ConstData("mask", U64(0x5555555555555555))
+	ghsh := GP64v()
+	PDEPQ(mask, lati, ghsh)
+	temp := GP64v()
+	PDEPQ(mask, lngi, temp)
+	SHLQ(U8(1), temp)
+	XORQ(temp, ghsh)
+
+	Store(ghsh, ReturnIndex(0))
+	RET()
+
+	Generate()
+}

examples/geohash/geohash.s

@@ -0,0 +1,34 @@
+// Code generated by command: go run asm.go -out geohash.s -stubs stub.go. DO NOT EDIT.
+
+#include "textflag.h"
+
+// func EncodeInt(lat float64, lng float64) uint64
+TEXT ·EncodeInt(SB), 0, $0-24
+	MOVSD	lat(FP), X0
+	MOVSD	lng+8(FP), X1
+	MULSD	reciprocal180<>(SB), X0
+	ADDSD	onepointfive<>(SB), X0
+	MULSD	reciprocal360<>(SB), X1
+	ADDSD	onepointfive<>(SB), X1
+	MOVQ	X0, CX
+	SHRQ	$0x14, CX
+	MOVQ	X1, AX
+	SHRQ	$0x14, AX
+	PDEPQ	mask<>(SB), CX, CX
+	PDEPQ	mask<>(SB), AX, AX
+	SHLQ	$0x01, AX
+	XORQ	AX, CX
+	MOVQ	CX, ret+16(FP)
+	RET
+
+DATA reciprocal180<>(SB)/8, $(0.005555555555555556)
+GLOBL reciprocal180<>(SB), RODATA, $8
+
+DATA onepointfive<>(SB)/8, $(1.5)
+GLOBL onepointfive<>(SB), RODATA, $8
+
+DATA reciprocal360<>(SB)/8, $(0.002777777777777778)
+GLOBL reciprocal360<>(SB), RODATA, $8
+
+DATA mask<>(SB)/8, $0x5555555555555555
+GLOBL mask<>(SB), RODATA, $8

examples/geohash/geohash_test.go

@@ -0,0 +1,13 @@
+package geohash
+
+import (
+	"testing"
+)
+
+//go:generate go run asm.go -out geohash.s -stubs stub.go
+
+func TestEncodeIntMountEverest(t *testing.T) {
+	if EncodeInt(27.988056, 86.925278) != 0xceb7f254240fd612 {
+		t.Fail()
+	}
+}

examples/geohash/stub.go

@@ -0,0 +1,5 @@
+// Code generated by command: go run asm.go -out geohash.s -stubs stub.go. DO NOT EDIT.
+
+package geohash
+
+func EncodeInt(lat float64, lng float64) uint64