idiv{bwl} r/m[8|16|32]

AX r/m8 -> AL

DX:AX r/m16 -> AX

EDX:EAX r/m32 -> EAX

`idiv` executes signed division. `idiv` divides a 16-, 32-, or 64-bit register value (dividend) by a register or memory byte, word, or long (divisor). The size of the divisor (8-, 16- or 32-bit operand) determines the particular register used as the dividend, quotient, and remainder.

Divisor Operand Size |
Dividend |
Quotient |
Remainder |
---|---|---|---|

byte |
AX |
AL |
AH |

word |
DX:AX |
AX |
DX |

long |
EDX:EAX |
EAX |
EDX |

If the resulting quotient is too large to fit in the destination, or if the divisor is 0, an Interrupt 0 is generated. Non-integral quotients are truncated toward 0. The remainder has the same sign as the dividend; the absolute value of the remainder is always less than the absolute value of the divisor.

Perform a 16-bit signed divide of the DX:AX register by the contents of the effective address (addressed by the EDI register plus an offset of 4) and store the quotient in the AX register

divw 4(%edi)

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