SH7261 datasheet(99/1348 Pages) RENESAS

tên linh kiện	SH7261

Giải thích chi tiết về linh kiện	32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

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Section 3 Floating-Point Unit (FPU)

Rev. 2.00 Sep. 07, 2007 Page 67 of 1312

REJ09B0320-0200

Section 3 Floating-Point Unit (FPU)

3.1

Features

The FPU has the following features.

• Conforms to IEEE754 standard

• 16 single-precision floating-point registers (can also be referenced as eight double-precision

registers)

• Two rounding modes: Round to nearest and round to zero

• Denormalization modes: Flush to zero

• Five exception sources: Invalid operation, divide by zero, overflow, underflow, and inexact

• Comprehensive instructions: Single-precision, double-precision, and 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.

3.2

Data Formats

3.2.1

Floating-Point Format

A floating-point number consists of the following three fields:

• Sign (s)

• Exponent (e)

• Fraction (f)

This LSI can handle single-precision and double-precision floating-point numbers, using the

formats shown in figures 3.1 and 3.2.

Figure 3.1 Format of Single-Precision Floating-Point Number

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