Appendix 5 Ieee754 Specification Overview; Appendix 5.1 Floating Point Formats - Renesas M32R-FPU Software Manual

APPENDICES

Appendix 5 IEEE754 Specification Overview

The following is a basic overview of the IEEE754 specification. M32R-FPU fulfills the
IEEE754 requirements through a combination of software and hardware features.

Appendix 5.1 Floating Point Formats

The following describes the floating-point formats.
Single Precision
Double Precision
Appendix Figure 5.1.1 Floating-Point Formats
s: Sign bit. 0 = positive number, 1 = negative numbers
e: Exponent. This represents a value that was made positive by adding 127 to a single
precision value or 1023 to a double precision value (biased exponent).
f : Fraction. Represents the fraction field of the value.
Using these symbols, the floating-point values (normalized numbers) can be described
by the following expressions:
Single-Precision Format: (–1) ^ s
Double-Precision Format: (–1) ^ s
• Certain values do not fit into the above expressions, such as
Number), denormalized numbers, etc.
• Other formats, such as expanded double precision, can also be used.
M32R-FPU only supports the single-precision format. The double precision format is
supported in the software library.
0 1 8 9
e (8 bit)
s (1 bit)
0 1 11 12
e (11 bit)
s (1 bit)
APPENDICES-18
Appendix 5 IEEE754 Specification Overview
31
f (23 bit)
f (52 bit)
1.f 2 ^ (e–127)
1.f 2 ^ (e–1023)
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, 0, NaN (Not a