Volume 4: Base IA-32 Instruction Reference
4:109
FCLEX/FNCLEX—Clear Exceptions
Description
Clears the floating-point exception flags (PE, UE, OE, ZE, DE, and IE), the exception
summary status flag (ES), the stack fault flag (SF), and the busy flag (B) in the FPU
status word. The FCLEX instruction checks for and handles any pending unmasked
floating-point exceptions before clearing the exception flags; the FNCLEX instruction
does not.
Operation
FPUStatusWord[0..7]
0;
FPUStatusWord[15]
0;
FPU Flags Affected
The PE, UE, OE, ZE, DE, IE, ES, SF, and B flags in the FPU status word are cleared. The
C0, C1, C2, and C3 flags are undefined.
Floating-point Exceptions
None.
Additional Itanium System Environment Exceptions
Itanium Reg Faults Disabled FP Register Fault if PSR.dfl is 1, NaT Register Consumption
Abort.
Protected Mode Exceptions
#NM
EM or TS in CR0 is set.
Real Address Mode Exceptions
#NM
EM or TS in CR0 is set.
Virtual 8086 Mode Exceptions
#NM
EM or TS in CR0 is set. /
Opcode
Instruction
Description
9B DB E2
FCLEX
Clear floating-point exception flags after checking for pending
unmasked floating-point exceptions.
DB E2
FNCLEX
Clear floating-point exception flags without checking for
pending unmasked floating-point exceptions.
Summary of Contents for ITANIUM ARCHITECTURE
Page 1: ......
Page 7: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 199: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 352: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 589: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 590: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 591: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 603: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...
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