dbg

Debug Hint (Thumb)

DBG #<option>

Debug hint (Thumb).

Details

Debug Hint provides a hint to the debugger about the execution state, encoded in a 4-bit option field. The instruction is a no-op from an architectural perspective and does not modify registers, memory, or condition flags. It is useful for marking debug checkpoints in code.

Pseudocode Operation

// Debug hint - architecturally NOP
// Debugger may act on option field
PC ← PC + instruction_length

Example

DBG #option

Encoding

Binary Layout
111100111010
1
1
1
1
10
0
0
0
000
1111
option
 
Format Thumb System
Opcode 0xF3AF80F0
Extension T32 (Base)

Operands

  • option
    Opt

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0x0320F0F0 DBG{<c>}{<q>} #<option> A32 cond | 00110 | 0 | 10 | 00 | 00 | 1 | 1 | 1 | 1 | 00001111 | option
0xF3AF80F0 DBG{<c>}{<q>} #<option> T32 111100111010 | 1 | 1 | 1 | 1 | 10 | 0 | 0 | 0 | 000 | 1111 | option

Description

DBG executes as a NOP. Arm deprecates any use of the DBG instruction.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();