fclass.d
Floating-Point Classify Double-Precision
The fclass.d instruction is defined analogously to its single-precision counterpart, but operates on double-precision
operands. It examines the value in floating-point register fs1 and writes to integer register xd a 10-bit mask that
indicates the class of the floating point number.
The format of the mask is described in the table below. The corresponding bit in xd will be set if the property
is true and clear otherwise. All other bits in xd are cleared. Note that exactly one bit in xd will be set.
| xd bit | Meaning |
|---|---|
0 |
fs1 is . |
1 |
fs1 is a negative normal number. |
2 |
fs1 is a negative subnormal number. |
3 |
fs1 is . |
4 |
fs1 is . |
5 |
fs1 is a positive subnormal number. |
6 |
fs1 is a positive normal number. |
7 |
fs1 is . |
8 |
fs1 is a signaling NaN. |
9 |
fs1 is a quiet NaN. |