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80386 Programmer's Reference Manual -- Opcode MOVZX

MOVZX -- Move with Zero-Extend

Opcode	Instruction	Clocks	Description	Example
0F B6 /r	movzx r/m8,r16	3/6	Move byte to word with zero-extend	`movzx %dl,%bx movzx (%ebx,1),%bx movzx m8(%ebx,1),%bx movzx m8(%ebx,%ebp,1),%bx`
0F B6 /r	movzx r/m8,r32	3/6	Move byte to dword, zero-extend	`movzx %dl,%ebx movzx (%ebx,1),%ebx movzx m8(%ebx,1),%ebx movzx m8(%ebx,%ebp,1),%ebx`
0F B7 /r	movzx r/m16,r32	3/6	Move word to dword, zero-extend	`movzx %cx,%ebx movzx (%ebx,1),%ebx movzx (%ebx,2),%ebx movzx (%ebx,%ebp,1),%ebx`

Operation




DEST := ZeroExtend(SRC);

Description

MOVZX reads the contents of the effective address or register as a byte or a word, zero extends the value to the operand-size attribute of the instruction (16 or 32 bits), and stores the result in the destination register.

Flags Affected

None

Protected Mode Exceptions

#GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page fault

Real Address Mode Exceptions

Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH

Virtual 8086 Mode Exceptions

Same exceptions as in Real Address Mode; #PF(fault-code) for a page fault

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