SH7785 Datasheet, PDF (156/1692 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

6. Floating-Point Unit (FPU)
6.2 Data Formats
6.2.1 Floating-Point Format
A floating-point number consists of the following three fields:
• Sign bit (s)
• Exponent field (e)
• Fraction field (f)
This LSI can handle single-precision and double-precision floating-point numbers, using the
formats shown in figures 6.1 and 6.2.
31 30
23 22
0
s
e
f
Figure 6.1 Format of Single-Precision Floating-Point Number
63 62
52 51
0
s
e
f
Figure 6.2 Format of Double-Precision Floating-Point Number
The exponent is expressed in biased form, as follows:
e = E + bias
The range of unbiased exponent E is E_min – 1 to E_max + 1. The two values E_min – 1 and E_max + 1 are
distinguished as follows. E_min – 1 indicates zero (both positive and negative sign) and a
denormalized number, and E_max + 1 indicates positive or negative infinity or a non-number (NaN).
Table 6.1 shows floating-point formats and parameters.
Rev.1.00 Jan. 10, 2008 Page 126 of 1658
REJ09B0261-0100