4-6
ColdFire CF4e Core User’s Manual
For More Information On This Product,
Go to: www.freescale.com
Operand Data Formats and Types
minimum value. If all the mantissa bits of the result are shifted off to the right during this
denormalization, the result becomes zero.
Denormalized numbers are not supported directly in the hardware of this implementation
but can be handled in software if needed (software for the input denorm exception could
be written to handle denormalized input operands, and software for the underflow
exception could create denormalized numbers). If the input denorm exception is disabled,
all denormalized numbers are treated as zeros.
Table 4-3 summarizes the data type specifications for byte, word, longword, single- and
double-precision data formats.
Table 4-3. Real Format Summary
Parameter
Single-Precision
Double-Precision
Data Format
Field Size in Bits
Sign (s)
1
1
Biased exponent (e)
8
11
Fraction (f)
23
52
Total
32
64
Interpretation of Sign
Positive fraction
s = 0
s = 0
Negative fraction
s = 1
s = 1
Normalized Numbers
Bias of biased exponent
+127 (0x7F)
+1023 (0x3FF)
Range of biased exponent
0
<
e
<
255 (0xFF)
0
<
e
<
2047 (0x7FF)
Range of fraction
Zero or Nonzero
Zero or Nonzero
Mantissa
1.f
1.f
Relation to representation of real numbers
(–1)
s
×
2
e–127
×
1.f
(–1)
s
×
2
e–1023
×
1.f
Denormalized Numbers
Biased exponent format minimum
0 (0x00)
0 (0x000)
Bias of biased exponent
+126 (0x7E)
+1022 (0x3FE)
Range of fraction
Nonzero
Nonzero
Mantissa
0.f
0.f
Relation to representation of real numbers
(–1)
s
×
2
–126
×
0.f
(–1)
s
×
2
–1022
×
0.f
Signed Zeros
Biased exponent format minimum
0 (0x00)
0 (0x00)
Mantissa
0.f = 0.0
0.f = 0.0
s
e
f
3130
23 22
0
s
e
f
6362
52 51
0
F
Freescale Semiconductor, Inc.
n
.