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

 145

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

The table below shows the saturating instructions:

For signed n-bit saturation, this means that:



If the value to be saturated is less than -2

n-1

, the result returned is -2



If the value to be saturated is greater than 2

n-1

-1, the result returned is 2

-1



Otherwise, the result returned is the same as the value to be saturated.

For unsigned n-bit saturation, this means that:



If the value to be saturated is less than 0, the result returned is 0



If the value to be saturated is greater than 2

-1, the result returned is 2

-1



Otherwise, the result returned is the same as the value to be saturated.

If the returned result is different from the value to be saturated, it is called saturation. If saturation occurs, the instruction
sets the Q flag to 1 in the APSR. Otherwise, it leaves the Q flag unchanged. To clear the Q flag to 0, the 

MSR

 instruction

.

To read the state of the Q flag, the 

MRS

.

SSAT

Signed Saturate

SSAT16

Signed Saturate Halfword

USAT

Unsigned Saturate

USAT16

Unsigned Saturate Halfword

QADD

Saturating Add

QSUB

Saturating Subtract

QSUB16

Saturating Subtract 16

QASX

Saturating Add and Subtract with Exchange

QSAX

Saturating Subtract and Add with Exchange

QDADD

Saturating Double and Add

QDSUB

Saturating Double and Subtract

UQADD16

Unsigned Saturating Add 16

UQADD8

Unsigned Saturating Add 8

UQASX

Unsigned Saturating Add and Subtract with Exchange

UQSAX

Unsigned Saturating Subtract and Add with Exchange

UQSUB16

Unsigned Saturating Subtract 16

UQSUB8

Unsigned Saturating Subtract 8