RealView Compilation Tools Assembler Guide: 4.6.3. SSAT16 and USAT16

Parallel halfword Saturating instructions.

SSAT16 saturates a signed value to a signed range.

USAT16 saturates a signed value to an unsigned range.

op{cond} Rd, #sat, Rn

where:

op

is one of:

cond

is an optional condition code (see Conditional execution).

Rd

is the destination register.

sat

specifies the bit position to saturate to, and is in the range 1 to 16 for SSAT16, or 0 to 15 for USAT16.

Rn

is the register holding the operand.

Do not use r15 for Rd or Rn.

Halfword-wise signed and unsigned saturation to any bit position.

The SSAT16 instruction saturates each signed halfword to the signed range -2^sat-1 ≤ x ≤ 2^sat-1 -1.

The USAT16 instruction saturates each signed halfword to the unsigned range 0 ≤ x ≤ 2^sat -1.

If saturation occurs on either halfword, these instructions set the Q flag. To read the state of the Q flag, use an MRS instruction (see MRS).

These ARM instructions are available in ARMv6 and above.

These 32-bit Thumb instructions are available in ARMv6T2 and above, except the ARMv7-M profile.

There are no 16-bit Thumb versions of these instructions.

    SSAT16  r7, #12, r7
    USAT16  r0, #7, r5

    SSAT16  r1, #16, r2, LSL #4 ; shifts not permitted with halfword saturations

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