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INSTRUCTION SET REFERENCE
FSUB/FSUBP/FISUBSubtract (Continued)
NOTES:
FMeans finite-real number.
IMeans integer.
*Indicates floating-point invalid-arithmetic-operand (#IA) exception.
Operation
IF instruction is FISUB
THEN
DEST
<
DEST
?
ConvertExtendedReal(SRC);
ELSE (* source operand is real number *)
DEST
<
DEST
?
SRC;
FI;
IF instruction is FSUBP
THEN
PopRegisterStack
FI;
FPU Flags Affected
C1
Set to 0 if stack underflow occurred.
Indicates rounding direction if the inexact result exception (#P) fault is
generated: 0 = not roundup; 1 = roundup.
C0, C2, C3
Undefined.
SRC
???
F or
?
I
?
0
+
0
+
F or +I+
?
NaN
??
*
??
??
??
??
??
NaN
?
F
+
¥
F or
±
0DESTDEST
?
F
??
NaN
DEST
?
0
+
??
SRC
±
0
?
0
?
SRC
??
NaN
+
0
+
??
SRC+0
±
0
?
SRC
??
NaN
+
F
+
?
+
FDESTDEST
±
F or
±
0
??
NaN
+
?
+
?
+
?
+
?
+
?
+
?
*NaN
NaNNaNNaNNaNNaNNaNNaNNaN
