bl.w

Branch with Link (Wide)

BL.W <label>

Thumb-2 32-bit Branch with Link.

Pseudocode Operation

if ConditionPassed() then
  LR ← PC + 4 | 1
  offset ← SignExtend(S || imm10 || J1 || J2 || imm11, 24)
  PC ← PC + (offset << 1)

Example

BL.W label

Encoding

Binary Layout

11110

31:27

S

26

imm10

25:16

11

15:14

J1

13

1

12

J2

11

imm11

10:0

 

Format Thumb Branch

Opcode 0xF000D000

Extension T32 (Thumb2)

Operands

• label
  Label

Related

More in T32 (Thumb2)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x0B000000	BL{<c>}{<q>} <label>		A32		cond | 101 | 1 | imm24
0xF000D000	BL{<c>}{<q>} <label>		T32		11110 | S | imm10 | 11 | J1 | 1 | J2 | imm11

Description

Branch with Link calls a subroutine at a PC-relative address, and setting LR to the return address. Branch with Link and Exchange Instruction Sets (immediate) calls a subroutine at a PC-relative address, setting LR to the return address, and changes the instruction set from A32 to T32, or from T32 to A32.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    if CurrentInstrSet() == InstrSet_A32 then
        LR = PC - 4;
    else
        LR = PC<31:1> : '1';
    bits(32) targetAddress;
    if targetInstrSet == InstrSet_A32 then
        targetAddress = Align(PC,4) + imm32;
    else
        targetAddress = PC + imm32;
    SelectInstrSet(targetInstrSet);
    BranchWritePC(targetAddress, BranchType_DIRCALL);