Renesas M32R-FPU Manual Do Utilizador

APPENDICES

APPENDICES-18

M32R-FPU Software Manual (Rev.1.01)

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.

APPENDIX 5

Appendix 5 IEEE754 Specification Overview

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

1.f

2 ^ (e–127)

Double-Precision Format: (–1) ^ s

1.f

2 ^ (e–1023)

• Certain values do not fit into the above expressions, such as

±∞

0, NaN (Not a

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.

s (1 bit)

e (8 bit)

Single Precision

f (23 bit)

0 1

8 9

s (1 bit)

e (11 bit)

Double Precision

f (52 bit)

0 1

11 12