206 G12 OEM Board & Sensor Reference Manual
represent values less than 1 (binary). For example, the number 1.625 (decimal)
can be represented as:
1.101 (binary) which is equal to:
2
0
+ 2
-1
+ 2
-3
(decimal) which is equal to:
1 + 0.5 + 0.125 (decimal) which is equal to:
1.625 (decimal).
The Represented Value
The value of the number being represented is equal to the exponent multiplied by
the fractional value, with the sign specified by the sign bit field.
If both the exponent field and the fraction field are equal to zero, the number being represented will
also be zero.
Note that in some systems (Intel-based PCs in particular) the order of the bytes will be reversed.
Single-Precision Float
The single precision format uses four consecutive bytes, with the 32 bits
containing a sign bit field, an 8-bit biased exponent field, and a 23-bit fraction
field. The exponent has a bias of 7F (hexadecimal). The fraction field is precise to
7 decimal digits. The single-precision format can represent values in the range
1.18*10
-38
to 3.4*10
38
(decimal), 1.
In 1, the value 1.0 is calculated by the following method:
1. The sign of the value is positive because the sign bit field is equal to 0.
Table B.1. Single-Precision Format
31-28 27-24 23-20 19-16 15-12 11-8 7-4 3-0
S EXPONENT FRACTION VALUE
0000 0000 0000 0000 0000 0000 0000 0000 0.0
0011 1111 1000 0000 0000 0000 0000 0000 1.0
1111 1111 1111 1111 1111 1111 1111 1111 NAN
(not a number)
0011 1111 0100 0000 0000 0000 0000 0000 0.75
G12RevD.book Page 206 Tuesday, April 2, 2002 4:33 PM
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