Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Hoja De Datos

 152

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Saturating Add and Saturating Subtract Unsigned.

Syntax

op{cond} {Rd}, Rn, Rm

op{cond} {Rd}, Rn, Rm

where:

op

is one of:

UQADD8 Saturating four unsigned 8-bit integer additions.

UQADD16 Saturating two unsigned 16-bit integer additions.

UDSUB8 Saturating four unsigned 8-bit integer subtractions.

UQSUB16 Saturating two unsigned 16-bit integer subtractions.

cond

Rd

is the destination register.

Rn, Rm

are registers holding the first and second operands.

Operation

These instructions add or subtract two or four values and then writes an unsigned saturated value in the destination
register. 

The UQADD16 instruction:



Adds the respective top and bottom halfwords of the first and second operands.



Saturates the result of the additions for each halfword in the destination register to the unsigned range 0 £ x £ 2

16

-

1, where x is 16.

The UQADD8 instruction:



Adds each respective byte of the first and second operands.



Saturates the result of the addition for each byte in the destination register to the unsigned range 0 £ x £ 2

8

-1, 

where x is 8.

The UQSUB16 instruction:



Subtracts both halfwords of the second operand from the respective halfwords of the first operand.



Saturates the result of the differences in the destination register to the unsigned range 0 £ x £ 2

16

-1, where x is 16.

The UQSUB8 instructions:



Subtracts the respective bytes of the second operand from the respective bytes of the first operand.



Saturates the results of the differences for each byte in the destination register to the unsigned range 0 £ x £ 2

8

-1, 

where x is 8.

Restrictions

Do not use SP and do not use PC

Condition Flags

These instructions do not affect the condition code flags.

Examples

UQADD16

R7, R4, R2

; Adds halfwords in R4 to corresponding halfword in R2,

; saturates to 16 bits, writes to corresponding halfword of R7

UQADD8

R4, R2, R5

; Adds bytes of R2 to corresponding byte of R5, saturates

; to 8 bits, writes to corresponding bytes of R4

UQSUB16

R6, R3, R0

; Subtracts halfwords in R0 from corresponding halfword

; in R3, saturates to 16 bits, writes to corresponding

; halfword in R6

UQSUB8

R1, R5, R6

; Subtracts bytes in R6 from corresponding byte of R5,

; saturates to 8 bits, writes to corresponding byte of R1.