Section 6 Floating-Point Unit
6.1
Overview
The floating-point unit (FPU) has the following features:
•
•
Conforms to IEEE754 standard
32 single-precision floating-point registers (can also be referenced as 16 double-precision
registers)
•
•
•
Two rounding modes: Round to Nearest and Round to Zero
Two denormalization modes: Flush to Zero and Treat Denormalized Number
Six exception sources: FPU Error, Invalid Operation, Divide By Zero, Overflow, Underflow,
and Inexact
•
Comprehensive instructions: Single-precision, double-precision, graphics support, system
control
When the FD bit in SR is set to 1, the FPU cannot be used, and an attempt to execute an FPU
instruction will cause an FPU disable exception.
6.2
Data Formats
6.2.1
Floating-Point Format
A floating-point number consists of the following three fields:
•
•
•
Sign (s)
Exponent (e)
Fraction (f)
The SH7750 Series can handle single-precision and double-precision floating-point numbers,
using the formats shown in figures 6.1 and 6.2.
31 30
s
23 22
0
e
f
Figure 6.1 Format of Single-Precision Floating-Point Number
Rev. 6.0, 07/02, page 161 of 986
RENESAS [ RENESAS TECHNOLOGY CORP ]
