Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Hoja De Datos

 137

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Restrictions

In these instructions:



Do not use SP and do not use PC.



RdHi and RdLo must be different registers.

Condition Flags

These instructions do not affect the condition code flags.

Examples

SMLAL

R4, R5, R3, R8

; Multiplies R3 and R8, adds R5:R4 and writes to

; R5:R4

SMLALBT

R2, R1, R6, R7

; Multiplies bottom halfword of R6 with top

; halfword of R7, sign extends to 32-bit, adds

; R1:R2 and writes to R1:R2

SMLALTB

R2, R1, R6, R7

; Multiplies top halfword of R6 with bottom

; halfword of R7,sign extends to 32-bit, adds R1:R2

; and writes to R1:R2

SMLALD

R6, R8, R5, R1

; Multiplies top halfwords in R5 and R1 and bottom

; halfwords of R5 and R1, adds R8:R6 and writes to

; R8:R6

SMLALDX

R6, R8, R5, R1

; Multiplies top halfword in R5 with bottom

; halfword of R1, and bottom halfword of R5 with

; top halfword of R1, adds R8:R6 and writes to

; R8:R6.

Signed Multiply Subtract Dual and Signed Multiply Subtract Long Dual

Syntax

op{X}{cond} Rd, Rn, Rm, Ra

where:

op

is one of:

SMLSD Signed Multiply Subtract Dual.

SMLSDX Signed Multiply Subtract Dual Reversed.

SMLSLD Signed Multiply Subtract Long Dual.

SMLSLDX Signed Multiply Subtract Long Dual Reversed.

SMLAW Signed Multiply Accumulate (word by halfword).

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

Rd

is the destination register.

Rn, Rm

are registers holding the first and second operands.

Ra

is the register holding the accumulate value.

Operation

The SMLSD instruction interprets the values from the first and second operands as four signed halfwords. This
instruction:



Optionally rotates the halfwords of the second operand.



Performs two signed 16 × 16-bit halfword multiplications.



Subtracts the result of the upper halfword multiplication from the result of the lower halfword multiplication.