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The thresholds for divide are simple and based only on the
difference of the exponents of the dividend and the divisor. It
is not possible in a divide operation for the significand to overflow
and cause an increment of the exponent. However, it is possible
for the significand to require a single bit left shift and the exponent
to be decremented for normalization. To reduce logic complexity,
the overflow ranges are the same as those of the LSA operations
in FADD and FSUB. The underflow
ranges include the minimum normal exponent, 0x01 for single-precision
and 0x001 for double-precision. Table 23.10 shows the FDIV
bounce thresholds. The exponent values shown in Table 23.10 are in biased
format.
Table 23.10. FDIV bounce thresholds
| Initial quotient exponent value | Float value | Condition in full-compliance mode | ||
|---|---|---|---|---|
| DP[1] | SP[2] | SP | DP | |
>0x7FF | - | DP overflow | - | Bounce |
0x7FF | - | DP NaN or infinity | - | Bounce |
0x7FE | - | DP maximum normal | - | Bounce |
0x7FD | - | DP normal | - | Bounce |
0x7FC | - | DP normal | - | Normal |
>0x47F | >0xFF | SP overflow | Bounce | Normal |
0x47F | 0xFF | SP NaN or infinity | Bounce | Normal |
0x47E | 0xFE | SP maximum normal | Bounce | Normal |
0x47D | 0xFD | SP normal | Bounce | Normal |
0x47C | 0xFC | SP normal | Normal | Normal |
0x3FF | 0x7F | e = 0 bias value | Normal | Normal |
0x382 | 0x02 | SP normal | Normal | Normal |
0x381 | 0x01 | SP normal | Bounce | Normal |
0x380 | 0x00 | SP subnormal | Bounce | Normal |
<0x380 | <0x00 | SP underflow | Bounce | Normal |
0x002 | - | DP normal | - | Normal |
0x001 | - | DP normal | - | Bounce |
0x000 | - | DP subnormal | - | Bounce |
<0x000 | - | DP underflow | - | Bounce |
[1] DP = double-precision. [2] SP = single-precision. | ||||