Integer Instructions
4-106 M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL MOTOROLA
EXT, EXTB Sign-Extend EXT, EXTB
(M68000 Family)
Operation: Destination Sign-Extended → Destination
Assembler EXT.W Dnextend byte to word
Syntax: EXT.L Dnextend word to long word
EXTB.L Dnextend byte to long word (MC68020, MC68030
MC68040, CPU32)
Attributes: Size = (Word, Long)
Description: Extends a byte in a data register to a word or a long word, or a word in a data
register to a long word, by replicating the sign bit to the left. If the operation extends a
byte to a word, bit 7 of the designated data register is copied to bits 15 – 8 of that data
register. If the operation extends a word to a long word, bit 15 of the designated data
register is copied to bits 31 – 16 of the data register. The EXTB form copies bit 7 of the
designated register to bits 31 – 8 of the data register.
Condition Codes:
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.
Instruction Format:
Instruction Fields:
Opmode field—Specifies the size of the sign-extension operation.
010—Sign-extend low-order byte of data register to word.
011—Sign-extend low-order word of data register to long.
111— Sign-extend low-order byte of data register to long.
Register field—Specifies the data register is to be sign-extended.
XNZVC
—∗∗00
1514131211109876543210
0100100 OPMODE 0 0 0 REGISTER
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