Multiply Without Accumulate - Analog Devices ADSP-BF53x Blackfin Reference

Multiply Accumulators (Multipliers)
For example:
A1 += R3.H * R4.H ;
In this instruction, the
and accumulates the result with the previous results in the
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
the high half of the result is extracted and stored in the 16-bit des-
tination registers (see
• 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
2-44 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
multiplier/accumulator performs a multiply
MAC1
Figure 2-12).
A1
option, then
IH
Figure 2-13).