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SSAT16

Signed Saturate 16 saturates two signed 16-bit values to a selected signed range.

This instruction sets PSTATE.Q to 1 if the operation saturates.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

313029282726252423222120191817161514131211109876543210
!= 111101101010sat_immRd(1)(1)(1)(1)0011Rn
cond

A1

SSAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>

d = UInt(Rd);  n = UInt(Rn);  saturate_to = UInt(sat_imm)+1;
if d == 15 || n == 15 then UNPREDICTABLE;

T1

15141312111098765432101514131211109876543210
11110(0)110010Rn0000Rd00(0)(0)sat_imm

T1

SSAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>

d = UInt(Rd);  n = UInt(Rn);  saturate_to = UInt(sat_imm)+1;
if d == 15 || n == 15 then UNPREDICTABLE; // Armv8-A removes UNPREDICTABLE for R13

For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors.

Assembler Symbols

<c>

See Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<Rd>

Is the general-purpose destination register, encoded in the "Rd" field.

<imm>

Is the bit position for saturation, in the range 1 to 16, encoded in the "sat_imm" field as <imm>-1.

<Rn>

Is the general-purpose source register, encoded in the "Rn" field.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    (result1, sat1) = SignedSatQ(SInt(R[n]<15:0>), saturate_to);
    (result2, sat2) = SignedSatQ(SInt(R[n]<31:16>), saturate_to);
    R[d]<15:0> = SignExtend(result1, 16);
    R[d]<31:16> = SignExtend(result2, 16);
    if sat1 || sat2 then
        PSTATE.Q = '1';
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