first pass at DATA sections

examples/data/asm.go

@@ -0,0 +1,34 @@
+// +build ignore
+
+package main
+
+import (
+	"math"
+
+	. "github.com/mmcloughlin/avo/build"
+	. "github.com/mmcloughlin/avo/operand"
+)
+
+func main() {
+	bytes := GLOBL("bytes")
+	DATA(0, U64(0x0011223344556677))
+	DATA(8, String("strconst"))
+	DATA(16, F32(math.Pi))
+	DATA(24, F64(math.Pi))
+	DATA(32, U32(0x00112233))
+	DATA(36, U16(0x4455))
+	DATA(38, U8(0x66))
+	DATA(39, U8(0x77))
+
+	// TEXT ·DataAt(SB),0,$0-9
+	TEXT("DataAt", "func(i int) byte")
+	i := Load(Param("i"), GP64v()) // MOVQ	i+0(FP), AX
+	ptr := Mem{Base: GP64v()}
+	LEAQ(bytes, ptr.Base) // LEAQ	b<>+0x00(SB), BX
+	b := GP8v()
+	MOVB(ptr.Idx(i, 1), b)   // MOVB	0(BX)(AX*1), CL
+	Store(b, ReturnIndex(0)) // MOVB	CL, ret+8(FP)
+	RET()                    // RET
+
+	Generate()
+}

examples/data/data.s

@@ -0,0 +1,21 @@
+// Code generated by command: go run asm.go -out data.s -stubs stub.go. DO NOT EDIT.
+
+#include "textflag.h"
+
+DATA bytes<>(SB)/8, $0x0011223344556677
+DATA bytes<>+8(SB)/8, $"strconst"
+DATA bytes<>+16(SB)/4, $(3.1415927)
+DATA bytes<>+24(SB)/8, $(3.141592653589793)
+DATA bytes<>+32(SB)/4, $0x00112233
+DATA bytes<>+36(SB)/2, $0x4455
+DATA bytes<>+38(SB)/1, $0x66
+DATA bytes<>+39(SB)/1, $0x77
+GLOBL ·bytes<>(SB), RODATA, $40
+
+// func DataAt(i int) byte
+TEXT ·DataAt(SB),0,$0-9
+	MOVQ	i(FP), AX
+	LEAQ	bytes<>(SB), CX
+	MOVB	(CX)(AX*1), AL
+	MOVB	AL, ret+8(FP)
+	RET

examples/data/data_test.go

@@ -0,0 +1,29 @@
+package data
+
+import (
+	"encoding/binary"
+	"math"
+	"testing"
+)
+
+//go:generate go run asm.go -out data.s -stubs stub.go
+
+func TestDataAt(t *testing.T) {
+	order := binary.LittleEndian
+	expect := make([]byte, 40)
+	order.PutUint64(expect[0:], 0x0011223344556677)         // DATA(0, U64(0x0011223344556677))
+	copy(expect[8:], []byte("strconst"))                    // DATA(8, String("strconst"))
+	order.PutUint32(expect[16:], math.Float32bits(math.Pi)) // DATA(16, F32(math.Pi))
+	order.PutUint64(expect[24:], math.Float64bits(math.Pi)) // DATA(24, F64(math.Pi))
+	order.PutUint32(expect[32:], 0x00112233)                // DATA(32, U32(0x00112233))
+	order.PutUint16(expect[36:], 0x4455)                    // DATA(36, U16(0x4455))
+	expect[38] = 0x66                                       // DATA(38, U8(0x66))
+	expect[39] = 0x77                                       // DATA(39, U8(0x77))
+
+	for i, e := range expect {
+		b := DataAt(i)
+		if b != e {
+			t.Errorf("DataAt(%d) = %#02x; expected %#02x", i, b, e)
+		}
+	}
+}

examples/data/stub.go

@@ -0,0 +1,5 @@
+// Code generated by command: go run asm.go -out data.s -stubs stub.go. DO NOT EDIT.
+
+package data
+
+func DataAt(i int) byte