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

167

SAM4S Series [DATASHEET]

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

Saturating Add and Subtract with Exchange and Saturating Subtract and Add with Exchange, unsigned.
Syntax

op{cond} {Rd}, Rm, Rn

where:
typeis one of:
UQASX Add and Subtract with Exchange and Saturate.
UQSAX Subtract and Add with Exchange and Saturate.
condis an optional condition code, see 

.

Rdis the destination register.
Rn, Rmare registers holding the first and second operands.
Operation
The UQASX instruction:

1. Adds the bottom halfword of the source operand with the top halfword of the second operand.

2. Subtracts the bottom halfword of the second operand from the top highword of the first operand.
3. Saturates the results of the sum and writes a 16-bit unsigned integer in the range 

0 ≤ x ≤ 2

16

 – 1, where x equals 16, to the top halfword of the destination register.

4. Saturates the result of the subtraction and writes a 16-bit unsigned integer in the range 0 ≤ x ≤ 2

16

 – 1, where 

 equals 16, to the bottom halfword of the destination register.

The UQSAX instruction:

1. Subtracts the bottom halfword of the second operand from the top highword of the first operand.

2. Adds the bottom halfword of the first operand with the top halfword of the second operand.
3. Saturates the result of the subtraction and writes a 16-bit unsigned integer in the range 0 ≤ x ≤ 2

16

 – 1, where 

 equals 16, to the top halfword of the destination register.

4. Saturates the results of the addition and writes a 16-bit unsigned integer in the range 0 ≤ x ≤ 2

16

 – 1, where 

 

equals 16, to the bottom halfword of the destination register.

Restrictions
Do not use SP and do not use PC

Condition Flags
These instructions do not affect the condition code flags.