127
SAM4CP [DATASHEET]
43051E–ATPL–08/14
12.6.6.2 UMULL, UMAAL, UMLAL
Unsigned Long Multiply, with optional Accumulate, using 32-bit operands and producing a 64-bit result.
Syntax
op
{
cond
}
RdLo
,
RdHi
,
Rn
,
Rm
where:
op
is one of:
UMULL Unsigned Long Multiply.
UMAAL Unsigned Long Multiply with Accumulate Accumulate.
UMLAL Unsigned Long Multiply, with Accumulate.
cond
is an optional condition code, see
“Conditional Execution”
.
RdHi, RdLo
are the destination registers. For UMAAL, UMLAL and UMLAL they also hold the accumulating value.
Rn, Rm
are registers holding the first and second operands.
Operation
These instructions interpret the values from
Rn
and
Rm
as unsigned 32-bit integers.
The UMULL instruction:
Multiplies the two unsigned integers in the first and second operands.
Writes the least significant 32 bits of the result in
RdLo.
Writes the most significant 32 bits of the result in
RdHi
.
The UMAAL instruction:
Multiplies the two unsigned 32-bit integers in the first and second operands.
Adds the unsigned 32-bit integer in
RdHi
to the 64-bit result of the multiplication.
Adds the unsigned 32-bit integer in
RdLo
to the 64-bit result of the addition.
Writes the top 32-bits of the result to
RdHi.
Writes the lower 32-bits of the result to
RdLo
.
The UMLAL instruction:
Multiplies the two unsigned integers in the first and second operands.
Adds the 64-bit result to the 64-bit unsigned integer contained in
RdHi
and
RdLo
.
Writes the result back to
RdHi
and
RdLo
.
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
UMULL R0, R4, R5, R6 ; Multiplies R5 and R6, writes the top 32 bits to R4
; and the bottom 32 bits to R0
UMAAL R3, R6, R2, R7 ; Multiplies R2 and R7, adds R6, adds R3, writes the
; top 32 bits to R6, and the bottom 32 bits to R3
UMLAL R2, R1, R3, R5 ; Multiplies R5 and R3, adds R1:R2, writes to R1:R2.