Assembler:Commands:IDIV

command idiv operand

Performs an unsigned division of two operands.

Divides (signed) the value in accumulator registers (dividend) by the source operand (divisor) and stores the result in the AX (AH:AL), DX:AX, or EDX:EAX registers. The source operand can be a general-purpose register or a memory location. The action of this instruction depends on the operand size (dividend/divisor).

The CF, OF, SF, ZF, AF, and PF flags are undefined.

Dividend	Divisor	Quotient	Remainder	Maximum Quotient
Word/Byte	AX	r/m8	AL	AH
Doubleword/Word	DX:AX	r/m16	AX	DX
Quadword/Doubleword	EDX:EAX	r/m32	EAX	EDX
Octoword/Quadword	RDX:RAX	r/m64	RAX	RDX

AL (r=AH) = AH:AL/operand : byte
AX (r=DX) = DX:AX/operand : WORD
EAX (r=EDX) = EDX:EAX/operand : DWORD
RAX (r=RDX) = RDX:RAX/operand : QWORD

Divides (signed) the value in the AX, DX:AX, or EDX:EAX registers (dividend) by the source operand (divisor) and stores the result in the AX (AH:AL), DX:AX, or EDX:EAX registers. The source operand can be a general-purpose register or a memory location. The action of this instruction depends on the operand size (dividend/divisor).

c9x.me/x86/html/file_module_x86_id_137.html

Command Parameters

Parameter	Description
operand	The divisor operand

Examples

idiv ecx

mov eax,6
mov edx,0
mov ecx,2
idiv ecx // eax (r=edx) = edx:eax / ecx
// eax = 3, edx = 0

mov eax,9
mov edx,0
mov esi,2
idiv esi // eax (r=edx) = edx:eax / esi
// eax = 4, edx = 1

mov eax,0
mov edx,1
mov esi,0x10
idiv esi // eax (r=edx) = edx:eax / esi
// eax = 0x10000000, edx = 0

mov eax,6
mov edx,0
mov [00123ABC],2
idiv [00123ABC] // eax (r=edx) = edx:eax / [00123ABC]
// eax = 6, edx = 0

mov eax,6
mov edx,0
mov [SomeSymbol],2
idiv [SomeSymbol] // eax (r=edx) = edx:eax / [SomeSymbol]
// eax = 6, edx = 0

See also

• Assembler
• Auto Assembler
• Assembler Commands

External links

• wikipedia.org/wiki/X86_instruction_listings
• wikibooks.org/wiki/X86_Assembly/Other_Instructions
• c9x.me/x86/
• ref.x86asm.net
• https://www.felixcloutier.com/x86