//
// Every potential sweeper must call begin() before they look
// for work, and end() after they've finished sweeping.
type activeSweep struct {
	// state is divided into two parts.
	//
	// The top bit (masked by sweepDrainedMask) is a boolean
	// value indicating whether all the sweep work has been
	// drained from the queue.
	//
	// The rest of the bits are a counter, indicating the

			break
		}
	}
}

func (a *Attribute) ABI() ABI { return ABI(a.load() / attrABIBase) }
func (a *Attribute) SetABI(abi ABI) {
	const mask = 1 // Only one ABI bit for now.
	for {
		v0 := a.load()
		v := (v0 &^ (mask * attrABIBase)) | Attribute(abi)*attrABIBase
		if atomic.CompareAndSwapUint32((*uint32)(a), uint32(v0), uint32(v)) {
			break
		}
	}
}

(MOVBUreg x:((FLES|FLTS|FEQS|FNES) _ _)) => x
(MOVBUreg x:((FLED|FLTD|FEQD|FNED) _ _)) => x
(MOVBUreg x:((SEQZ|SNEZ) _)) => x
(MOVBUreg x:((SLT|SLTU) _ _)) => x

// Avoid extending when already sufficiently masked.
(MOVBreg  x:(ANDI [c] y)) && c >= 0 && int64(int8(c)) == c => x
(MOVHreg  x:(ANDI [c] y)) && c >= 0 && int64(int16(c)) == c => x
(MOVWreg  x:(ANDI [c] y)) && c >= 0 && int64(int32(c)) == c => x

		bts[1] = 127
		binary.BigEndian.PutUint64(bts[2:10], uint64(f.Header.Length))
		n = 10

	default:
		return ws.ErrHeaderLengthUnexpected
	}

	if f.Header.Masked {
		bts[1] |= bit0
		n += copy(bts[n:], f.Header.Mask[:])
	}

	if _, err := w.Write(bts[:n]); err != nil {
		return err
	}

	_, err := w.Write(f.Payload)
	return err