Renesas SH7781 - Manual (Page 157)

6. Floating-Point Unit (FPU)
Rev.1.00 Jan. 10, 2008 Page 127 of 1658
REJ09B0261-0100
Table 6.1 Floating-Point Number Formats and Parameters
Parameter Single-Precision Double-Precision
Total bit width 32 bits 64 bits
Sign bit 1 bit 1 bit
Exponent field 8 bits 11 bits
Fraction field 23 bits 52 bits
Precision 24 bits 53 bits
Bias +127 +1023
E
max
+127 +1023
E
min
–126 –1022
Floating-point number value v is determined as follows:
If E = E
max
+ 1 and f
≠ 0, v is a non-number (NaN) irrespective of sign s
If E = E
max
+ 1 and f = 0, v = (–1) s (infinity) [positive or negative infinity]
If E
min
≤ E ≤ E
max
, v = (–1) s 2 E (1.f) [normalized number]
If E = E
min
– 1 and f
≠ 0, v = (–1) s 2 Emin (0.f) [denormalized number]
If E = E
min
– 1 and f = 0, v = (–1) s 0 [positive or negative zero]
Table 6.2 shows the ranges of the various numbers in hexadecimal notation. For the signaling non-
number and quiet non-number, see section 6.2.2, Non-Numbers (NaN). For the denormalized
number, see section 6.2.3, Denormalized Numbers.