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Motorola DSP96002 User Manual

Page 56

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MOTOROLA

DSP96002 USER’S MANUAL

5 - 3

is not aware that the data is represented in a floating point format. The range of the unbiased exponent, E,

is every integer between E

min

and E

max

, inclusive (-E

min

max

). For single precision (SP), E

min

= -126

while E

max

= +127; for double precision (DP), E

min

= -1022 while E

max

= +1023. For both SP and DP, E

min

-

1 is reserved to encode

±

0 and denormalized numbers while E

max

+1 is used to encode

±∞

and NaN’s.

5.2.2.1

IEEE Single Precision Real Memory Format Summary

23-Bit

Fraction

11-Bit

Exponent

S

52-Bit

Fraction

8-Bit

Exponent

S

SINGLE REAL

DOUBLE REAL

Sign of Significand

Sign of Significand

Figure 5-3. Memory Format for floating-point Operands

31 30

23 22

0

63 62

52 51

0

Field Size (in bits):


s = Sign ............... 1
e = Biased Exponent .... 8
f = Fraction ........... 23

Interpretation of Sign:


Positive Mantissa: s = 0
Negative Mantissa: s = 1

Normalized Numbers:

Represents real numbers in the form (-1)

s

x 2

(E+127)

x 1.f

E ........................ unbiased exponent -126 < E < +127
Bias of e .............. +127 ($7F)
e = E + bias .......... 0 < e < 254 ($FE)
f ...................... Zero or Non-Zero
Mantissa................ 1.f

Fraction

S

Biased

Exponent

31 30

23 22

0

31

0