NAME
	EXT, EXTB -- Sign extend

SYNOPSIS
	EXT.W	Dn	Extend byte to word
	EXT.L	Dn	Extend word to long word
	EXTB.L	Dn	Extend byte to long word	(68020+)

	Size = (Word, Long)

FUNCTION
	Extends a byte to a word, or a word to a long word in a data
	register by copying the sign bit through the upper bits. If the
	operation is from byte to word, bit 7 is copied to bits 8 through
	15. If the operation is from word to long word, bit 15 is copied
	to bits 16 through 31. The EXTB copies bit 7 to bits 8 through 31.

FORMAT
	-----------------------------------------------------------------
	|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
	|---|---|---|---|---|---|---|-----------|---|---|---|-----------|
	| 0 | 1 | 0 | 0 | 1 | 0 | 0 |  OP-MODE  | 0 | 0 | 0 | REGISTER  |
	-----------------------------------------------------------------

	"REGISTER" specifies a data register.

OP-MODE
	010->Extending from 8 bits to 16 bits.
	011->Extending from 16 bits to 32 bits.
	111->Extending from 8 bits to 32 bits.

RESULT
	X - Not affected
	N - Set if the result is negative. Cleared otherwise.
	Z - Set if the result is zero. Cleared otherwise.
	V - Always cleared
	C - Always cleared

SEE ALSO
	BFEXTS	BFEXTU