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

141

SAM4S Series [DATASHEET]

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

Unsigned Sum of Absolute Differences and Accumulate
Syntax

USADA8{cond}{Rd,} Rn, Rm, Ra

where:
condis an optional condition code, see 

.

Rdis the destination register.
Rnis the first operand register.
Rmis the second operand register.
Rais the register that contains the accumulation value.
Operation
The USADA8 instruction:

1. Subtracts each byte of the second operand register from the corresponding byte of the first operand register.

2. Adds the unsigned absolute differences together.
3. Adds the accumulation value to the sum of the absolute differences.
4. Writes the result to the destination register.

Restrictions
Do not use SP and do not use PC

Condition Flags
These instructions do not change the flags.
Examples

USADA8 R1, R0, R6

; Subtracts bytes in R0 from corresponding halfword of R1

; adds differences, adds value of R6, writes to R1

USADA8 R4, R0, R5, R2

; Subtracts bytes of R5 from corresponding byte in R0

 ; adds differences, adds value of R2 writes to R4.