Publication 1763-RM001C-EN-P - October 2009
190 Math Instructions
Using the Floating Point
(F) Data File
File Description
Floating point files contain IEEE-754 floating point data elements. One
floating point element is shown below. You can have up to 256 of these
elements in each floating point file.
Floating point numbers are represented using the IEEE-754 format, where:
• Bit 31 is the sign bit. This bit is set for negative numbers (note that
negative zero is a valid value).
• Bits 23 to 30 are the exponent.
• Bits 0 to 22 are the mantissa.
The value represented by a 32-bit floating point number (not one of the
exception values defined on page 191) is given by the following
expression. Note the restoration of the suppressed most significant bit of
the mantissa.
(-1)
s
x 2
e - 127
x (1 + m)
where:
s is the sign bit (0 or 1)
e is the exponent (1 to 254)
m is the mantissa (0 ≤ f < 1)
The valid range for floating point numbers is from -3.4028 x 10
38
to
+3.4028 x 10
38
.
Definitions
Overflow - occurs when the result of an operation produces an exponent
that is greater than 254.
Floating Point Data File Structure
Floating Point Element
31
30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
S
(1)
(1) S = Sign Bit
Exponent Value Mantissa
High Word Low Word
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