x86-64 FPSR Register
The bit settings of the x86-64 FPSR register are outlined in the following table.
Value
Bit Setting
Meaning
TOP=<i>
0x3800
Register <i> is top of FPU stack
B
0x8000
FPU busy
C0
0x0100
Condition bit 0
C1
0x0200
Condition bit 1
C2
0x0400
Condition bit 2
C3
0x4000
Condition bit 3
ES
0x0080
Exception summary status
SF
0x0040
Stack fault
EF=PE
0x0020
Precision exception
EF=UE
0x0010
Underflow exception
EF=OE
0x0008
Overflow exception
EF=ZE
0x0004
Zero divide exception
EF=DE
0x0002
Denormalized operand exception
EF=IE
0x0001
Invalid operation exception