FFREE
Free Floating
| Opcode | Mode | Leg Mode | Description | |
|---|---|---|---|---|
| DD C0+i | Sets tag for ST(i) to empty. |
Description
Sets the tag in the FPU tag register associated with register ST(i) to empty (11B). The contents of ST(i) and the FPU stack-top pointer (TOP) are not affected.
This instruction’s operation is the same in non-64-bit modes and 64-bit mode.
Operation
TAG(i) := 11B;
FPU Flags Affected
| C0, C1, C2, C3 | undefined. |
|---|
Floating-Point Exceptions
None
Protected Mode Exceptions
| #NM | CR0.EM[bit 2] or CR0.TS[bit 3] = 1. |
|---|---|
| #MF | If there is a pending x87 FPU exception. |
| #UD | If the LOCK prefix is used. |
Real-Address Mode Exceptions
Same exceptions as in protected mode.
Virtual-8086 Mode Exceptions
Same exceptions as in protected mode.
Compatibility Mode Exceptions
Same exceptions as in protected mode.
64-Bit Mode Exceptions
Same exceptions as in protected mode.
This UNOFFICIAL, mechanically-separated, non-verified reference is provided for convenience, but it may be incomplete or broken in various obvious or non-obvious ways. Refer to Intel® 64 and IA-32 Architectures Software Developer’s Manual for anything serious.