Atmel SAM4S Series, Preliminary Data Sheet

Page: 139 / 1163

139
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
11.6.6.4 SMLAD
Signed Multiply Accumulate Long Dual
Syntax
op{X}{cond} Rd, Rn, Rm, Ra ;
where:
Operation
The
SMLAD
and
SMLADX
instructions regard the two operands as four halfword 16-bit values. The
SMLAD
and
SMLADX
instructions:
• If
X
is not present, multiply the top signed halfword value in
Rn
with the top signed halfword of
Rm
and the bottom signed halfword values in
Rn
with the bottom signed halfword of
Rm
.
• Or if
X
is present, multiply the top signed halfword value in
Rn
with the bottom signed halfword
of
Rm
and the bottom signed halfword values in
Rn
with the top signed halfword of
Rm
.
• Add both multiplication results to the signed 32-bit value in
Ra
.
• Writes the 32-bit signed result of the multiplication and addition to
Rd
.
Restrictions
Do not use SP and do not use PC
.
Condition Flags
These instructions do not change the flags.
Examples
SMLAD R10, R2, R1, R5 ; Multiplies two halfword values in R2 with
; corresponding halfwords in R1, adds R5 and writes
; to R10
SMLALDX R0, R2, R4, R6 ; Multiplies top halfword of R2 with bottom halfword
; of R4, multiplies bottom halfword of R2 with top
; halfword of R4, adds R6 and writes to R0.
op is one of:
SMLAD Signed Multiply Accumulate Dual
SMLADX Signed Multiply Accumulate Dual Reverse
X specifies which halfword of the source register Rn is used as the multiply operand.
If
X
is omitted, the multiplications are bottom × bottom and top × top.
If X is present, the multiplications are bottom × top and top × bottom.
cond is an optional condition code, see “Conditional Execution” .
Rd is the destination register.
Rn is the first operand register holding the values to be multiplied.
Rm the second operand register.
Ra is the accumulate value.