Multiply Accumulators (Multipliers)
2-44
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
For example:
A1 += R3.H * R4.H ;
In this instruction, the
MAC1
multiplier/accumulator performs a multiply
and accumulates the result with the previous results in the
A1
Accumulator.
Multiply Without Accumulate
The multiplier may operate without the accumulation function. If accu-
mulation is not used, the result can be directly stored in a register from the
Data Register File or the Accumulator register. The destination register
may be 16 bits or 32 bits. If a 16-bit destination register is a low half, then
MAC0 is used; if it is a high half, then MAC1 is used. For a 32-bit desti-
nation register, either MAC0 or MAC1 is used.
If the destination register is 16 bits, then the word that is extracted from
the multiplier depends on the data type of the input.
• If the multiplication uses fractional operands or the
IH
option, then
the high half of the result is extracted and stored in the 16-bit des-
tination registers (see
Figure 2-12
).
• If the multiplication uses integer operands, then the low half of the
result is extracted and stored in the 16-bit destination registers.
These extractions provide the most useful information in the
resultant 16-bit word for the data type chosen (see
Figure 2-13
).
Содержание ADSP-BF53x Blackfin
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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...