embedded-coding-style

---

name: embedded-coding-style description: "Initialize embedded project context, then apply and verify MISRA-like C coding style rules with selectable scope, ANSI encoding policy, brace policy, header/doc comment policy, and verification checklist."

Embedded Coding Style Skill

Initialize project context first, then apply a strict, repeatable embedded C style policy to selected scope.

---

Initialization + Scope Selection

Step 0: Initialize Project Context (Mandatory)

Before any edit, initialize the project and gather context:

Get-Location
Get-ChildItem -Path <project_root>

If backup is provided, verify backup path exists before edits.

Step 1: Select Scope (Mandatory)

Choose one scope per run:

1. Driver layer only: <project_root>/<driver_dir>
2. BSP layer only: <project_root>/<bsp_dir>
3. App layer only: <project_root>/<app_dir>
4. Combined subset: any two scopes
5. Full target: all selected core scopes

Default behavior: if user does not specify scope, use full target scope.

Do not edit outside selected scope.

---

Hard Rules

1. Encoding: GB2312 (code page 936), mandatory.
2. Line ending: CRLF.
3. File end: one blank line (CRLF+CRLF).
4. Every .c/.h begins with:

/**
 * @file ...
 * @author  ...
 * @brief ...
 * @version ...
 * @date ...
 *
 * @copyright Copyright (c) 2026
 */

5. Function doc comment uses /** ... */ and includes @brief @param @retval.
6. Inline/block explanation comments use /* ... */.
7. Comment language: Chinese; avoid AI-template phrasing.
8. Standard headers use <> (e.g. <stdint.h>, <stdio.h>, <string.h>, <math.h>, <stddef.h>).
9. Project headers use "...".
10. Header files keep include guard and must contain C++ compatibility block:

#ifdef __cplusplus
extern "C" {
#endif

...

#ifdef __cplusplus
}
#endif

11. Left brace must be on a new line.
12. Brace indentation must align with control statement indentation.
13. Always use braces for single-line bodies:

• if
• while
• else if
• else
• (also keep for/switch/do as full blocks)

14. switch requires default.
15. Each case must end with explicit break/return (or controlled jump).
16. Prefer explicit comparisons; avoid implicit truthiness when unclear.
17. Integer literals should use explicit suffixes where applicable (U, UL).
18. Macro parameters/expressions require parentheses.
19. Multi-statement macros require do { ... } while (0).
20. Minimize global visibility: file-private symbols should be static.
21. Pointer params should be null-checked before dereference for externally reachable paths.
22. Avoid magic numbers; extract to macro/constant (prefer existing project style).
23. Do not alter timing/ISR/state-machine behavior for formatting-only tasks.
24. Text read/write encoding is mandatory GB2312 (code page 936), no auto-detect, no fallback encoding.
25. Read path must use strict GB2312 decoding (decoder exception fallback enabled); if decode fails, stop immediately.
26. Write path must use strict GB2312 encoding (encoder exception fallback enabled); if encode fails, stop immediately and rollback.
27. Remove obvious AI-style comments (for example: /* global variable with static scope */); rewrite as natural engineering comments that describe current module intent/context, not generic coding slogans.
28. Struct-pointer function parameters must use unified name handle (for example: static void gpio_control_work(GPIO_Control_t *handle)), avoid mixed aliases such as p_ctrl/p_xxx.

---

Execution Procedure

Step 2: Pre-check Files in Selected Scope

Enumerate selected files only:

Get-ChildItem -Path <selected_scope_paths> -Recurse -File

Step 3: Safe Edit Strategy

• Edit in small passes (headers first, then braces, then comments).
• Avoid broad regex that can touch function comments repeatedly.
• For file header replacement, replace only the first top-of-file block comment.
• During comment cleanup, rewrite AI-template comments into natural project comments; preserve technical meaning and avoid repetitive rule-recitation wording.
• During signature cleanup, rename struct-pointer parameters to handle consistently and update in-function references in the same scope.
• Run strict encoding preflight before first write:
  • Force GB2312 decode for source text (code page 936).
  • Decoder fallback must be exception-based; any decode error means immediate stop.
  • Do not switch to UTF-8/UTF-16/other encodings as fallback.
• Required operation: explicit GB2312 read + explicit GB2312 write for every touched .c/.h file.

Step 4: Brace Normalization

• Convert control statements to newline brace style.
• Add missing braces to all single-line if/while/else if/else bodies.
• Ensure opening brace indent equals control-statement indent.

Step 5: Header/C++ Guard Normalization

• Keep include guard.
• Ensure exactly one open C++ block and one close C++ block.
• Place close C++ block immediately before final #endif of include guard.

Step 6: Include Normalization

• Convert standard C headers from "x.h" to <x.h>.
• Keep project headers in "x.h".

Step 7: Final Newline + Encoding Pass

• Normalize newline to CRLF.
• Trim trailing blank noise.
• Force final CRLF+CRLF.
• Write using GB2312 (code page 936) with strict encoder fallback (exception on unmappable chars).

---

Verification Checklist

Run and confirm all are clean (within selected scope only):

1. if/while/else if/else without brace:

rg -n "^\s*(if|while|else\s+if|else)\b" <selected_scope_paths>

2. C++ guards exist in headers:

rg -n "#ifdef __cplusplus|extern \"C\"|#endif" <selected_scope_paths>

3. File header presence:

rg -n "^/\*\*|@file|@author|@brief|@version|@date" <selected_scope_paths>

4. Tail bytes check (13,10,13,10 expected):

Get-ChildItem <selected_scope_paths> -Recurse -File | ForEach-Object {
  $b=[IO.File]::ReadAllBytes($_.FullName)
  $tail=if($b.Length -ge 4){$b[($b.Length-4)..($b.Length-1)]}else{$b}
  "{0}:{1}" -f $_.FullName,($tail -join ',')
}

5. Spot-check random files for Chinese comment readability.
6. Encoding safety check:

rg -n "\?\?\?|\uFFFD" <selected_scope_paths>

Result must be empty for newly changed content.

---

Recovery / Rollback

• If text becomes mojibake or strict GB2312 decode/encode throws:
  • Stop immediately.
  • Restore from known-good backup.
  • Re-apply rules with explicit strict GB2312 read/write configuration.
• Never perform non-GB2312 encode/decode cycles.
• Do not continue batch edits after detecting corruption or codec exception.
• If strict GB2312 preflight fails, only allow byte-level operations (copy/backup/line-ending check), no semantic rewrite.

---

Success Criteria

• All files in selected scope comply with Hard Rules.
• No mojibake/no ? replacement damage in Chinese comments.
• No unintended behavior changes.
• Diff is style-focused and reviewable.