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
Summary of Contents for ADSP-BF53x Blackfin
Page 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 604: ...Instruction Overview 15 92 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...