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Section 3 Floating-Point Unit (FPU)
Page 96 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
3.2 Data Formats
3.2.1 Floating-Point Format
A floating-point number consists of the following three fields:
Sign (s)
Exponent (e)
Fraction (f)
This LSI can handle single-precision and double-precision floating-point numbers, using the
formats shown in figures 3.1 and 3.2.
31 30
23 22
0
s
e
f
Figure 3.1 Format of Single-Precision Floating-Point Number
63 62
52 51
0
s
e
f
Figure 3.2 Format of Double-Precision Floating-Point Number
The exponent is expressed in biased form, as follows:
e = E + bias
The range of unbiased exponent E is E
min
– 1 to E
max
+ 1. The two values E
min
– 1 and E
max
+ 1 are
distinguished as follows. E
min
– 1 indicates zero (both positive and negative sign) and a
denormalized number, and E
max
+ 1 indicates positive or negative infinity or a non-number (NaN).
Table 3.1 shows E
min
and E
max
values.