Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

148

Signed Dual Multiply Add and Signed Dual Multiply Subtract

Syntax

op{X}{cond} Rd, Rn, Rm

where:

op

is one of:

SMUAD Signed Dual Multiply Add.

SMUADX Signed Dual Multiply Add Reversed.

SMUSD Signed Dual Multiply Subtract.

SMUSDX Signed Dual Multiply Subtract Reversed.

If X is present, the multiplications are bottom × top and top × bottom.
If the X is omitted, the multiplications are bottom × bottom and top × top.

cond

is an optional condition code, see 

.

Rd

is the destination register.

Rn, Rm

are registers holding the first and second operands.

Operation

The SMUAD instruction interprets the values from the first and second operands as two signed halfwords in each
operand. This instruction: 



Optionally rotates the halfwords of the second operand.



Performs two signed 16 × 16-bit multiplications.



Adds the two multiplication results together.



Writes the result of the addition to the destination register.

The SMUSD instruction interprets the values from the first and second operands as two’s complement signed
integers. This instruction:



Optionally rotates the halfwords of the second operand.



Performs two signed 16 × 16-bit multiplications.



Subtracts the result of the top halfword multiplication from the result of the bottom halfword multiplication.



Writes the result of the subtraction to the destination register.

Restrictions

In these instructions:



Do not use SP and do not use PC.

Condition Flags

Sets the Q flag if the addition overflows. The multiplications cannot overflow.