7-27
FLOATING-POINT UNIT
NOTES:
1.Integer bit is implied and not stored for single-real and double-real formats.
2.The fraction for SNaN encodings must be non-zero.
7.4.2.Binary Integers
The FPUs three binary integer data types (word, short, and long) have identical formats, except
for length. Table 7-8 gives the precision and range of these data types and Figure 7-17 gives the
formats. Table 7-10 gives the encodings of the three binary integer types.
Table 7-9. Real Number and NaN Encodings
Class
SignBiased Exponent
Significand
Integer
1
Fraction
Positive+
?
0
11..11
1
00..00
+Normals
0
.
.
0
11..10
.
.
00..01
1
.
.
1
11..11
.
.
00..00
+Denormals
0
.
.
0
00..00
.
.
00..00
0
.
.
0
11.11
.
.
00..01
+Zero
0
00..00
0
00..00
Negative
?
Zero
1
00..00
0
00..00
?
Denormals
1
.
.
1
00..00
.
.
00..00
0
.
.
0
00..01
.
.
11..11
?
Normals
1
.
.
1
00..01
.
.
11..10
1
.
.
1
00..00
.
.
11..11
??
1
11..11
1
00..00
NaNs
SNaN
X
11..11
1
0X..XX
2
QNaN
X
11..11
1
1X..XX
Real Indefinite
(QNaN)
1
11..11
1
10..00
Single-Real:
Double-Real:
Extended-Real
<
8 Bits
>
<
11 Bits
>
<
15 Bits
>
<
23 Bits
>
<
52 Bits
>
<
63 Bits
>
