4.3.12.2.1 DSP Multiply Instructions

The DSP instructions that use the multiplier are summarized in Table 4-4.

Table 4-4. DSP Instructions that Use the Multiplier
DSP Instruction⁽¹⁾	Description	Algebraic Equivalent
`MAC`	Multiply and Add to Accumulator or Square and Add to Accumulator	a = a + b c* or a = a + b²
`MSC`	Multiply and Subtract from Accumulator	a = a – b c*
`MPY`	Multiply	a = b c*
`MPY.N`	Multiply and Negate Result	a = -b c*
`SQR`	Square to Accumulator	a = b²
`SQRAC`	Square and Accumulate	a = a + (b²)
`ED`	Partial Euclidean Distance	a = (b – c)²
`EDAC`	Add Partial Euclidean Distance to the Accumulator	a = a + (b – c)²
Note: DSP instructions using the multiplier can operate in Fractional (1.15/1.31) or Integer modes.

The DSP Multiplier Unsigned/Signed Control (US[1:0]) bits (CORCON[12]) determine whether the DSP multiply instructions are signed (default), unsigned or mixed-sign. The US[1] bit does not influence the MCU multiply instructions, which have specific instructions for a signed or unsigned operation. If the USx bit is set to '1', the input operands for instructions shown in Table 4-4 are considered as unsigned values, which are always zero-extended into the 33rd bit of the multiplier value. If the USx bit is set to ‘00’, the operands are sign-extended.