R01UH0822EJ0100 Rev.1.00
Page 51 of 1041
Jul 31, 2019
RX13T Group
2. CPU
Note 1. Writing 0 to the bit clears it. Writing 1 to the bit does not affect its value.
Note 2. Positive denormalized numbers are treated as +0, negative denormalized numbers as –0.
Note 3. When the EV bit is set to 0, the FV flag is enabled.
Note 4. When the EO bit is set to 0, the FO flag is enabled.
Note 5. When the EZ bit is set to 0, the FZ flag is enabled.
Note 6. When the EU bit is set to 0, the FU flag is enabled.
Note 7. When the EX bit is set to 0, the FX flag is enabled.
Note 8. Once the bit has been set to 1, this value is retained until it is cleared to 0 by software.
The floating-point status word (FPSW) indicates the results of floating-point operations.
When an exception handling enable bit (Ej) enables the exception handling (Ej = 1), the exception cause can be identified
by checking the corresponding Cj flag in the exception handling routine. If the exception handling is masked (Ej = 0), the
occurrence of exception can be checked by reading the Fj flag at the end of a series of processing. Once the Fj flag has
been set to 1, this value is retained until it is cleared to 0 by software (j = X, U, Z, O, or V).
RM[1:0] Bits (Floating-Point Rounding-Mode Setting)
These bits specify the floating-point rounding-mode.
Explanation of Floating-Point Rounding Modes
Rounding towards the nearest value (the default behavior): An inexact result is rounded to the available value that is
closest to the result which would be obtained with an infinite number of digits. If two available values are equally
close, rounding is to the even alternative.
Rounding towards 0: An inexact result is rounded to the smallest available absolute value, i.e. in the direction of
zero (simple truncation).
Rounding t
: An inexact result is rounded to the nearest available value in the direction of positive
infinity.
b8
0 Flush Bit of Denormalized Number
0: A denormalized number is handled as a denormalized
number.
1: A denormalized number is handled as 0.*
R/W
b9
—
Reserved
This bit is read as 0. The write value should be 0.
R/W
b10
Invalid Operation Exception Enable
0: Invalid operation exception is masked.
1: Invalid operation exception is enabled.
R/W
b11
Overflow Exception Enable
0: Overflow exception is masked.
1: Overflow exception is enabled.
R/W
b12
Division-by-Zero Exception Enable
0: Division-by-zero exception is masked.
1: Division-by-zero exception is enabled.
R/W
b13
Underflow Exception Enable
0: Underflow exception is masked.
1: Underflow exception is enabled.
R/W
b14
Inexact Exception Enable
0: Inexact exception is masked.
1: Inexact exception is enabled.
R/W
b25 to b15 —
Reserved
These bits are read as 0. The write value should be 0.
R/W
b26
Invalid Operation Flag
0: No invalid operation has been encountered.
1: Invalid operation has been encountered.*
R/W
b27
Overflow Flag
0: No overflow has occurred.
1: Overflow has occurred.*
R/W
b28
Division-by-Zero Flag
0: No division-by-zero has occurred.
1: Division-by-zero has occurred.*
R/W
b29
Underflow Flag
0: No underflow has occurred.
1: Underflow has occurred.*
R/W
b30
Inexact Flag
0: No inexact exception has been generated.
1: Inexact exception has been generated.*
R/W
b31
Floating-Point Error Summary Flag
This bit reflects the logical OR of the FU, FZ, FO, and FV
flags.
R
Bit
Symbol
Bit Name
Description
R/W