printing: commit some refactors (probably broken)

printer/goasm.go

@@ -0,0 +1,63 @@
+package printer
+
+import (
+	"strings"
+
+	"github.com/mmcloughlin/avo"
+	"github.com/mmcloughlin/avo/internal/prnt"
+	"github.com/mmcloughlin/avo/operand"
+)
+
+// dot is the pesky unicode dot used in Go assembly.
+const dot = "\u00b7"
+
+type goasm struct {
+	cfg Config
+	prnt.Generator
+}
+
+func NewGoAsm(cfg Config) Printer {
+	return &goasm{cfg: cfg}
+}
+
+func (p *goasm) Print(f *avo.File) ([]byte, error) {
+	p.header()
+	for _, fn := range f.Functions {
+		p.function(fn)
+	}
+	return p.Result()
+}
+
+func (p *goasm) header() {
+	p.NL()
+	p.include("textflag.h")
+	p.NL()
+}
+
+func (p *goasm) include(path string) {
+	p.Printf("#include \"%s\"\n", path)
+}
+
+func (p *goasm) function(f *avo.Function) {
+	p.Comment(f.Stub())
+	p.Printf("TEXT %s%s(SB),0,$%d-%d\n", dot, f.Name, f.FrameBytes(), f.ArgumentBytes())
+
+	for _, node := range f.Nodes {
+		switch n := node.(type) {
+		case *avo.Instruction:
+			p.Printf("\t%s\t%s\n", n.Opcode, joinOperands(n.Operands))
+		case avo.Label:
+			p.Printf("%s:\n", n)
+		default:
+			panic("unexpected node type")
+		}
+	}
+}
+
+func joinOperands(operands []operand.Op) string {
+	asm := make([]string, len(operands))
+	for i, op := range operands {
+		asm[i] = op.Asm()
+	}
+	return strings.Join(asm, ", ")
+}