pkhtb

Pack Halfword Top Bottom

PKHTB<c> <Rd>, <Rn>, <Rm> {, ASR #<imm>}

Combines top half of Rn with bottom half of shifted Rm.

Pseudocode Operation

shifted_rm ← Rm >> shift_imm
Rd[15:0] ← shifted_rm[15:0]
Rd[31:16] ← Rn[31:16]

Example

PKHTB r0, r1, r2

Encoding

Binary Layout

cond

31:28

01101000

27:20

Rn

19:16

Rd

15:12

imm5

11:7

1

6

01

5:4

Rm

3:0

 

Format Data Proc

Opcode 0x06800050

Extension A32 (DSP)

Operands

• Rd
  Destination general-purpose register
• Rn
  Top Src
• Rm
  Bottom Src

Related

More in A32 (DSP)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x06800050	PKHTB{<c>}{<q>} {<Rd>,} <Rn>, <Rm> {, ASR #<imm>}		A32		cond | 01101000 | Rn | Rd | imm5 | 1 | 01 | Rm
0xEAC00020	PKHTB{<c>}{<q>} {<Rd>,} <Rn>, <Rm> {, ASR #<imm>}		T32		1110101 | 0110 | 0 | Rn | 0 | imm3 | Rd | imm2 | 1 | 0 | Rm

Description

Pack Halfword combines one halfword of its first operand with the other halfword of its shifted second operand.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    operand2 = Shift(R[m], shift_t, shift_n, PSTATE.C);  // PSTATE.C ignored
    R[d]<15:0>  = if tbform then operand2<15:0> else R[n]<15:0>;
    R[d]<31:16> = if tbform then R[n]<31:16>    else operand2<31:16>;