Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Scheda Tecnica

SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

154

; subtracts R7, rounds and writes to R3

SMMLS

R4, R5, R3, R8

; Multiplies R5 and R3, extracts top 32 bits, 

; subtracts R8, truncates and writes to R4.

Signed Most Significant Word Multiply
Syntax

op{R}{cond} Rd, Rn, Rm

where:
opis one of:
SMMUL Signed Most Significant Word Multiply.
Ris a rounding error flag. If R is specified, the result is rounded instead of being

truncated. In this case the constant 0x80000000 is added to the product before

the high word is extracted.
condis an optional condition code, see 

.

Rdis the destination register.
Rn, Rmare registers holding the first and second operands.
Operation
The SMMUL instruction interprets the values from Rn and Rm as two’s complement 32-bit signed integers. The 

SMMUL instruction:



Multiplies the values from Rn and Rm.



Optionally rounds the result, otherwise truncates the result.



Writes the most significant signed 32 bits of the result in Rd.

Restrictions
In this instruction:



do not use SP and do not use PC.

Condition Flags
This instruction does not affect the condition code flags.
Examples

SMULL

R0, R4, R5

; Multiplies R4 and R5, truncates top 32 bits

 ; and writes to R0

SMULLR  R6, R2

 ; Multiplies R6 and R2, rounds the top 32 bits

; and writes to R6.

Signed Dual Multiply Add and Signed Dual Multiply Subtract
Syntax

op{X}{cond} Rd, Rn, Rm

where:
opis one of:
SMUAD Signed Dual Multiply Add.