356
Floating-point Math Instructions
Section 5-24
Limitations
The augend (Au+1 and Au) and Addend (Ad+1 and Ad) data must be in
IEEE754 floating-point data format.
DM 6143 to DM 6655 cannot be used for R.
Description
When the execution condition is OFF, +F(––) is not executed. When the exe-
cution condition is ON, +F(––) adds the 32-bit floating-point number in Ad+1
and Ad to the 32-bit floating-point number in Au+1 and Au and places the
result in R+1 and R. (The floating point data must be in IEEE754 format.)
If the absolute value of the result is greater than the maximum value that can
be expressed as floating-point data, the Overflow Flag (SR 25404) will turn
ON and the result will be output as
±∞
.
If the absolute value of the result is less than the minimum value that can be
expressed as floating-point data, the Underflow Flag (SR 25405) will turn ON
and the result will be output as 0.
The various combinations of augend and addend data will produce the results
shown in the following table.
Note
1.
The results could be zero (including underflows), a numeral, +
∞
, or –
∞
.
2.
The Error Flag will be turned ON and the instruction won’t be executed.
Flags
ER:
Indirectly addressed EM/DM word is non-existent.
(Content of
*
EM/
*
DM word is not BCD, or the EM/DM area boundary
has been exceeded.)
ON if the augend or addend data is not recognized as floating-point
data.
EQ:
ON if both the exponent and mantissa of the result are 0.
OF:
ON if the absolute value of the result is too large to be expressed as a
32-bit floating-point value. (The result will be output as
±∞
.)
UF:
ON if the absolute value of the result is too small to be expressed as a
32-bit floating-point value. (The result will be output as 0.)
Augend
Addend
0
Numeral
+
∞
–
∞
NaN
0
0
Numeral
+
∞
–
∞
Numeral
Numeral
See note 1.
+
∞
–
∞
+
∞
+
∞
+
∞
+
∞
See note 2.
–
∞
–
∞
–
∞
See note 2.
–
∞
NaN
See note 2.
R+1
R
Au
Augend (floating-point data, 32 bits)
Au+1
Ad
Addend (floating-point data, 32 bits)
Ad+1
Result (floating-point data, 32 bits)
+
