// 12.7: Double-Precision Floating-Point Classify Instruction
	AFCLASSD

	// 13.1 Quad-Precision Load and Store Instructions
	AFLQ
	AFSQ

	// 13.2: Quad-Precision Computational Instructions
	AFADDQ
	AFSUBQ
	AFMULQ
	AFDIVQ
	AFMINQ
	AFMAXQ
	AFSQRTQ
	AFMADDQ
	AFMSUBQ
	AFNMADDQ
	AFNMSUBQ

	// 13.3 Quad-Precision Convert and Move Instructions
	AFCVTWQ
	AFCVTLQ
	AFCVTSQ
	AFCVTDQ

    String dottedQuad = ipString.substring(lastColon + 1);
    byte[] quad = textToNumericFormatV4(dottedQuad);
    if (quad == null) {
      return null;
    }
    String penultimate = Integer.toHexString(((quad[0] & 0xff) << 8) | (quad[1] & 0xff));
    String ultimate = Integer.toHexString(((quad[2] & 0xff) << 8) | (quad[3] & 0xff));
    return initialPart + penultimate + ":" + ultimate;
  }

    String dottedQuad = ipString.substring(lastColon + 1);
    byte[] quad = textToNumericFormatV4(dottedQuad);
    if (quad == null) {
      return null;
    }
    String penultimate = Integer.toHexString(((quad[0] & 0xff) << 8) | (quad[1] & 0xff));
    String ultimate = Integer.toHexString(((quad[2] & 0xff) << 8) | (quad[3] & 0xff));
    return initialPart + penultimate + ":" + ultimate;
  }

	HasAVX5124FMAPS     bool // Advanced vector extension 512 Fused Multiply Accumulation Packed Single precision
	HasAVX512VPOPCNTDQ  bool // Advanced vector extension 512 Double and quad word population count instructions
	HasAVX512VPCLMULQDQ bool // Advanced vector extension 512 Vector carry-less multiply operations
	HasAVX512VNNI       bool // Advanced vector extension 512 Vector Neural Network Instructions

//   - "::ffff:1.2.3.4" (if [Addr.Is4In6])
//   - IPv6 with zone ("fe80:db8::1%eth0")
//
// Note that unlike package net's IP.String method,
// IPv4-mapped IPv6 addresses format with a "::ffff:"
// prefix before the dotted quad.
func (ip Addr) String() string {
	switch ip.z {
	case z0:
		return "invalid IP"
	case z4:
		return ip.string4()
	default:
		if ip.Is4In6() {
			return ip.string4In6()
		}