usat16

Unsigned Saturate 16 (A32)

USAT16<c> <Rd>, #<imm>, <Rm>

Saturates two unsigned 16-bit values.

Pseudocode Operation

lower_hw ← Rm[15:0] (unsigned)
upper_hw ← Rm[31:16] (unsigned)
sat_max ← 2^imm - 1
if lower_hw > sat_max then
  Rd[15:0] ← sat_max
  Q ← 1
else
  Rd[15:0] ← lower_hw
if upper_hw > sat_max then
  Rd[31:16] ← sat_max
  Q ← 1
else
  Rd[31:16] ← upper_hw

Example

USAT16 r0, #16, r2

Encoding

Binary Layout

cond

31:28

01101

27:23

1

22

10

21:20

sat_imm

19:16

Rd

15:12

1

11

1

10

1

9

1

8

0011

7:4

Rn

3:0

 

Format Data Proc

Opcode 0x06E00F30

Extension A32 (DSP)

Operands

• Rd
  Destination general-purpose register
• imm
  Bit Position
• Rm
  Second source / offset general-purpose register

Related

More in A32 (DSP)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x06E00F30	USAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>		A32		cond | 01101 | 1 | 10 | sat_imm | Rd | 1 | 1 | 1 | 1 | 0011 | Rn
0xF3A00000	USAT16{<c>}{<q>} <Rd>, #<imm>, <Rn>		T32		11110 | 0 | 11 | 10 | 1 | 0 | Rn | 0 | 000 | Rd | 00 | 0 | 0 | sat_imm

Description

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.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    (result1, sat1) = UnsignedSatQ(SInt(R[n]<15:0>), saturate_to);
    (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';