3-163
INSTRUCTION SET REFERENCE
FABS—Absolute Value
Description
This instruction clears the sign bit of ST(0) to create the absolute value of the operand. The
following table shows the results obtained when creating the absolute value of various classes
of numbers.
NOTE:
F Means finite-real number.
Operation
ST(0)
<
|ST(0)|
FPU Flags Affected
C1
Set to 0 if stack underflow occurred; otherwise, cleared to 0.
C0, C2, C3
Undefined.
Floating-Point Exceptions
#IS
Stack underflow occurred.
Protected Mode Exceptions
#NM
EM or TS in CR0 is set.
Opcode
Instruction
Description
D9 E1
FABS
Replace ST with its absolute value.
ST(0) SRC
ST(0) DEST
??
+
?
?
F
+F
?
0
+0
+
0
+0
+F
+F
+
?
+
?
NaN
NaN
