ADSP-BF53x/BF56x Blackfin Processor Programming Reference
2-19
Computational Units
Rounding Multiplier Results
On many multiplier operations, the processor supports multiplier results
rounding (
RND
option). Rounding is a means of reducing the precision of a
number by removing a lower order range of bits from that number’s repre-
sentation and possibly modifying the remaining portion of the number to
more accurately represent its former value. For example, the original num-
ber will have N bits of precision, whereas the new number will have only
M bits of precision (where N>M). The process of rounding, then, removes
N – M bits of precision from the number.
The
RND_MOD
bit in the
ASTAT
register determines whether the
RND
option
provides biased or unbiased rounding. For unbiased rounding, set
RND_MOD
bit = 0. For biased rounding, set
RND_MOD
bit = 1.
L
For most algorithms, unbiased rounding is preferred.
Figure 2-6. Integer Multiplier Results Format
31 31 31 31 31 31 31 31
30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
31
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
31 30 29 28 27 26 25 24 23 22 21 20 1
1
1 16
7
6
5
4
3
2
1
0
P SIGN,
8 BITS
MULTIPLIER P OUTPUT
A0.X
A0.W
Содержание ADSP-BF53x Blackfin
Страница 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
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Страница 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
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Страница 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 780: ...Product Identification Register 21 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 994: ...Instructions Listed By Operation Code C 194 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...