routine

Deep inside an ECU file there is the code — the program the ECU runs. routine lets you peek at that code without specialised tools: give it a file and an offset (a position inside the file) and it decodes the instructions around that spot into readable one-line pseudo-code.

It is deliberately not a full decompiler — it will not rename variables or rebuild loops for you. Think of it as a phrasebook: it translates each instruction into one plain line so you can get a feel for what the code does. The line nearest your offset is marked with >>.

When do I need it?

• Curiosity / learning. "What is actually running here?" — flip a few offsets and read.
• Cross-checking with scan-maps or analyze. Those tools say a table is "referenced by code"; routine lets you look at that code.
• No Ghidra installed — for quick looks, this is enough.

Which "language" it decodes is chosen automatically from the ECU family (Rust C166 decoder, or capstone for TriCore / SuperH / x86 / 68k-family). If the family is unknown you can force a decoder with --arch.

Try it (2 minutes)

openremap routine my-file.bin 0x50000

The output starts with a header naming the file, the offset, and the decoder used, then lists one instruction per line:

  my-file.bin  @ 0x50000  (c166)

  >> 0x00050000   <instruction nearest your offset>
     0x00050002   <next instruction>
     ...

(The >> line is your target. Instructions before and after it are shown too, so you can see the surrounding routine.)

Understanding the answer

Use --before / --after to widen or narrow the window around the target, and --arch to pick the decoder yourself when auto-detection cannot (it will tell you if the family has no decoder).

For developers

The same decode is one method of openremap.api:

Where to go next