Numeric Formats
2-8
ADSP-2126x SHARC Processor Hardware Reference
The short float type supports gradual underflow. This method sacrifices
precision for dynamic range. When packing a number which would have
underflowed, the exponent is set to zero and the mantissa (including “hid-
den” 1) is right-shifted the appropriate amount. The packed result is a
denormal, which can be unpacked into a normal IEEE floating-point
number.
Table 2-2. FPACK Operations
Condition
Result
135 < exp
Largest magnitude representation.
120 < exp
135
Exponent is Most Significant Bit (MSB) of source exponent concatenated
with the three Least Significant Bits (LSBs) of source exponent. The
packed fraction is the rounded upper 11 bits of the source fraction.
109 < exp
120
Exponent = 0. Packed fraction is the upper bits (source exponent – 110)
of the source fraction prefixed by zeros and the “hidden” one. The packed
fraction is rounded.
exp < 110
Packed word is all zeros.
exp = source exponent
sign bit remains the same in all cases
Table 2-3. FUNPACK Operations
Condition
Result
0 < exp
15
Exponent is the 3 LSBs of the source exponent prefixed by the MSB of
the source exponent and four copies of the complement of the MSB. The
unpacked fraction is the source fraction with 12 zeros appended.
exp = 0
Exponent is (120 – N) where N is the number of leading zeros in the
source fraction. The unpacked fraction is the remainder of the source
fraction with zeros appended to pad it and the “hidden” one stripped
away.
exp = source exponent
sign bit remains the same in all cases
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 ...