Intel Extensible Firmware Interface - Manual (Page 799)

EFI Byte Code Virtual Machine
Version 1.10 12/01/02 19-25
DIVU
SYNTAX:
DIVU[32|64] {@}R
1
, {@}R
2
{Index16|Immed16}
DESCRIPTION:
Performs a divide operation on two unsigned operands and stores the result to Operand 1. The
operation can be performed on either 32-bit (DIVU32) or 64-bit (DIVU64) operands.
OPERATION:
Operand 1 <= Operand 1 / Operand 2
Table 19-17 DIVU Instruction Encoding
BYTE DESCRIPTION
Bit Description
7 0 = Immediate/index absent
1 = Immediate/index present
6 0 = 32-bit operation
1 = 64-bit operation
0
0..5 Opcode = 0x11
Bit Description
7 0 = Operand 2 direct
1 = Operand 2 indirect
4..6 Operand 2
3 0 = Operand 1 direct
1 = Operand 1 indirect
1
0..2 Operand 1
2..3 Optional 16-bit immediate data/index
BEHAVIORS AND RESTRICTIONS:
• If Operand 2 is indirect, then the immediate data is interpreted as an index, and the value is
fetched from memory as an unsigned value at address [R
2
+ Index16].
• If Operand 2 is direct, then the immediate data is considered an unsigned value and is added to
the Operand 2 register contents such that Operand 2 = R
2
+ Immed16
• For the DIVU32 form, if Operand 1 is direct then the upper 32 bits of the result are set to 0
before storing back to the Operand 1 register.
• A divide-by-0 exception occurs if Operand 2 = 0.