[dev.cc] cmd/asm: add addr package

This simple package holds the definition of the Addr (address) type
that represents addresses inside the assembler.

It has no dependencies.

Change-Id: I7573fd70f1847ef68e3d6b663dc4c39eb2ebf8b3
Reviewed-on: https://go-review.googlesource.com/3193
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/asm/internal/addr/addr.go

@@ -0,0 +1,112 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package addr holds the definition of an instruction address.
+package addr
+
+// Addr represents a parsed address.
+type Addr struct {
+	IsStatic            bool    // symbol<>
+	IsImmediateConstant bool    // $3
+	IsImmediateAddress  bool    // $main·main(SB)
+	IsIndirect          bool    // (R1)
+	HasRegister         bool    // register is set
+	HasRegister2        bool    // register2 is set
+	HasFloat            bool    // float is set
+	HasOffset           bool    // offset is set
+	HasString           bool    // string is set
+	Symbol              string  // "main·main"
+	Register            int16   // R1
+	Register2           int16   // R1 in R0:R1
+	Offset              int64   // 3
+	Float               float64 // 1.0e2 (floating constant)
+	String              string  // "hi" (string constant)
+	Index               int16   // R1 in (R1*8)
+	Scale               int8    // 8 in (R1*8)
+}
+
+const (
+	// IsStatic does not appear here; Is and Has methods ignore it.
+	ImmediateConstant = 1 << iota
+	ImmediateAddress
+	Indirect
+	Symbol
+	Register
+	Register2
+	Offset
+	Float
+	String
+	Index
+	Scale
+)
+
+// Has reports whether the address has any of the specified elements.
+// Indirect and immediate are not checked.
+func (a *Addr) Has(mask int) bool {
+	if mask&Symbol != 0 && a.Symbol != "" {
+		return true
+	}
+	if mask&Register != 0 && a.HasRegister {
+		return true
+	}
+	if mask&Register2 != 0 && a.HasRegister2 {
+		return true
+	}
+	if mask&Offset != 0 && a.HasOffset {
+		return true
+	}
+	if mask&Float != 0 && a.HasFloat {
+		return true
+	}
+	if mask&String != 0 && a.HasString {
+		return true
+	}
+	if mask&Index != 0 && a.Index != 0 {
+		return true
+	}
+	if mask&Scale != 0 && a.Scale != 0 {
+		return true
+	}
+	return false
+}
+
+// Is reports whether the address has exactly the specified elements.
+// Indirect and immediate are checked.
+func (a *Addr) Is(mask int) bool {
+	if (mask&ImmediateConstant == 0) != !a.IsImmediateConstant {
+		return false
+	}
+	if (mask&ImmediateAddress == 0) != !a.IsImmediateAddress {
+		return false
+	}
+	if (mask&Indirect == 0) != !a.IsIndirect {
+		return false
+	}
+	if (mask&Symbol == 0) != (a.Symbol == "") {
+		return false
+	}
+	if (mask&Register == 0) != !a.HasRegister {
+		return false
+	}
+	if (mask&Register2 == 0) != !a.HasRegister2 {
+		return false
+	}
+	if (mask&Offset == 0) != !a.HasOffset {
+		// $0 has the immediate bit but value 0.
+		return false
+	}
+	if (mask&Float == 0) != !a.HasFloat {
+		return false
+	}
+	if (mask&String == 0) != !a.HasString {
+		return false
+	}
+	if (mask&Index == 0) != (a.Index == 0) {
+		return false
+	}
+	if (mask&Scale == 0) != (a.Scale == 0) {
+		return false
+	}
+	return true
+}