# decomp.me recipe — 01_memset

## Create a scratch

Open https://decomp.me/ (or your self-hosted instance at
http://192.168.88.64 if available). Click **New scratch**.

- **Platform / Compiler:** `gcc 12.x aarch64-linux-gnu` (or whatever
  aarch64-gcc is offered — exact version doesn't matter much for this
  size).
- **Compiler flags:** `-O2 -ffreestanding -nostdlib`
- **Diff label:** `memset_byte`

## Target asm

Paste the following into the **"Target asm"** box:

```asm
memset_byte:
    mov     x3, #0x0
.Lloop:
    cmp     x2, x3
    b.ne    .Lbody
    ret
.Lbody:
    strb    w1, [x0, x3]
    add     x3, x3, #0x1
    b       .Lloop
```

## Context (headers/decls)

```c
#include <stddef.h>
#include <stdint.h>
```

## Source

Paste the ground-truth C from `reference.c` (or write your own first
and iterate).

## Expected workflow

- First compile: scorer usually reports a high similarity (>= 80%) if
  the compiler picks the same `while (i != n)` pattern.
- Fine-tune: try `i++` vs `i+=1`, try `while` vs `for`, try `uint8_t *`
  cast placement. Each yields a distinct register-allocation order the
  scorer rewards or punishes.
- Perfect match possible if you hit the exact code shape GCC chose.

## Benchmark notes

- decomp.me's strength is the **compile-and-diff** feedback loop — every
  edit immediately shows the byte-delta against the target.
- Weakness for this target: the real blob was likely built with a
  different compiler (ARMCC / Keil / vendor LLVM?). GCC may never match
  exactly even with perfect C. Similarity >= 90% is the realistic ceiling.