adr.w

Form PC-relative Address (Wide)

ADR.W <Rd>, <label>

Thumb-2 32-bit ADR.

Details

Thumb-2 32-bit form PC-relative address: Rd ← PC + offset, where the offset is computed from the immediate fields encoded as a 12-bit modified immediate. The assembler calculates the label-relative offset and encodes it. Does not modify condition flags. Execution state: T32 only.

Pseudocode Operation

offset ← expand_12bit_imm(i : imm3 : imm8)
Rd ← Align(PC, 4) + offset

Example

ADR.W r0, label

Encoding

Binary Layout
11110
i
10
0
0
0
0
1111
0
imm3
Rd
imm8
 
Format Thumb Data Proc
Opcode 0xF20F0000
Extension T32 (Thumb2)

Operands

  • Rd
    Destination general-purpose register
  • label
    Label

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0x028F0000 ADR{<c>}{<q>} <Rd>, <label> A32 cond | 0010 | 100 | 0 | 1111 | Rd | imm12
0x024F0000 ADR{<c>}{<q>} <Rd>, <label> A32 cond | 0010 | 010 | 0 | 1111 | Rd | imm12
0xA000 ADR{<c>}{<q>} <Rd>, <label> T32 1010 | 0 | Rd | imm8
0xF2AF0000 ADR{<c>}{<q>} <Rd>, <label> T32 11110 | i | 10 | 1 | 0 | 1 | 0 | 1111 | 0 | imm3 | Rd | imm8
0xF20F0000 ADR{<c>}.W <Rd>, <label> T32 11110 | i | 10 | 0 | 0 | 0 | 0 | 1111 | 0 | imm3 | Rd | imm8

Description

Form PC-relative address adds an immediate value to the PC value to form a PC-relative address, and writes the result to the destination register.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    result = if add then (Align(PC,4) + imm32) else (Align(PC,4) - imm32);
    if d == 15 then          // Can only occur for A32 encodings
        ALUWritePC(result);
    else
        R[d] = result;