ARM v7-M Instruction Set Decoding Function

Question

Is there any instruction decoder for the ARM v7-M Instruction Set, that I can just give it an opcode as parameter and return me with the corresponding instruction type?

For example: MOV Rd, <op2>

has four different versions depending on the <op2>.

1. A simple register specifier, for example Rm.
2. An immediate shifted register, for example Rm, LSL #4.
3. A register shifted register, for example Rm, LSL Rs.
4. An immediate value, for example #0xE000E000.

I want to know which of this version it is from the opcode of the instruction?

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Editors note: opcode means the actual 'hex' instruction or machine encoding. The question is about the assembler mnemonic. On many CPUs a leading mnemonic may map to different opcodes (or machine instructions) depending on the arguments.

Answer 1

Yes, it's called a disassembler. Put the op code in an assembly file, build it, and then disassemble it.

$ cat in.s
    .syntax unified
    .align  2
    .code   16
    .globl  _foo
    .thumb_func _foo
_foo:
    .short  0x4615
    .long   0x43e0e92d

$ clang -arch armv7m -c in.s
$ otool -arch armv7m -tv in.o
in.o:
(__TEXT,__text) section
_foo:
00000000        4615    mov r5, r2
00000002    e92d43e0    push.w  {r5, r6, r7, r8, r9, lr}