Texas Instruments TMS320C67X/C67X+ DSP manual 2. Double-Precision Floating-Point Fields

Overview of IEEE Standard Single- and Double-Precision Formats

Table 3−5 shows hexadecimal and decimal values for some single-precision floating-point numbers.

Figure 3−2 shows the fields of a double-precision floating-point number repre- sented within a pair of 32-bit registers.

Table 3−5. Hexadecimal and Decimal Representation for Selected Single-Precision Values

Symbol	Hex Value	Decimal Value
NaN_out	7FFF FFFF	QNaN
0	0000 0000	0.0
−0	8000 0000	−0.0
1	3F80 0000	1.0
2	4000 0000	2.0
LFPN	7F7F FFFF	3.40282347e+38
SFPN	0080 0000	1.17549435e−38
LDFPN	007F FFFF	1.17549421e−38
SDFPN	0000 0001	1.40129846e−45

Figure 3−2. Double-Precision Floating-Point Fields

31	30	20	19	0	31	0
s		e		f		f
		Odd register				Even register

Legend: s sign bit (0 = positive, 1 = negative)

e11-bit exponent ( 0 < e < 2047)

f52-bit fraction

0 < f < 1*2−1 + 1*2−2 + ... + 1*2−52 or 0 < f < ((252)−1)/(252)

The floating-point fields represent floating-point numbers within two ranges: normalized (e is between 0 and 2047) and denormalized (e is 0). The following formulas define how to translate the s, e, and f fields into a double-precision floating-point number.

3-12 Instruction Set SPRU733