USAT16 -- AArch32

USAT16

Unsigned Saturate 16 saturates two signed 16-bit values to a selected unsigned 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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
!= 1111				0	1	1	0	1	1	1	0	sat_imm				Rd				(1)	(1)	(1)	(1)	0	0	1	1	Rn
cond

A1

USAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>

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

T1

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	1	1	0	(0)	1	1	1	0	1	0	Rn				0	0	0	0	Rd				0	0	(0)	(0)	sat_imm

T1

USAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>

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

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 0 to 15, encoded in the "sat_imm" field.

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

Operation

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

Internal version only: isa v01_31, pseudocode v2024-03_rel ; Build timestamp: 2024-03-25T10:05