
Numeric Formats
2-4
ADSP-2126x SHARC Processor Hardware Reference
IEEE Single-precision Floating-point Data Format
IEEE Standard 754/854 specifies a 32-bit single-precision floating-point
format, shown in
. A number in this format consists of a sign
bit (
s
), a 24-bit significand, and an 8-bit unsigned-magnitude exponent
(
e
).
For normalized numbers, the significand consists of a 23-bit fraction f and
a “hidden” bit of 1 that is implicitly presumed to precede f
22
in the signif-
icand. The binary point is presumed to lie between this hidden bit and f
22
.
The Least Significant Bit (LSB) of the fraction is f
0
; the LSB of the expo-
nent is
e0
.
The hidden bit effectively increases the precision of the floating-point sig-
nificand to 24 bits from the 23 bits actually stored in the data format. It
also insures that the significand of any number in the IEEE normalized
number format is always greater than or equal to one and less than two.
The unsigned exponent,
e
, can range between 1
e
254 for normal
numbers in the single-precision format. This exponent is biased by
+127 (254, 2). To calculate the true unbiased exponent, 127 must be sub-
tracted from
e
.
Figure 2-2. IEEE 32-Bit Single-Precision Floating-Point Format
s
e0
31
30
23
22
0
1 . f22
f0
e7
• • •
HIDDEN BIT
BINARY POINT
• • •
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...