NandDumpGUI

A Windows WPF application to decode/correct NAND raw dumps (data + OOB) using BCH ECC.
It can export a fixed data-only image (page data) and optionally a fixed RAW (data + OOB) where corrected bytes and ECC can be rewritten.

The UI supports:

• Primitive polynomial presets + manual polynomial input
• Transform modes: none, inv, bitrev, inv+bitrev
• Custom NAND layout (page/oob/sector/chunk/ecc offset/len)
• Quick Test: tries multiple parameter combinations on a sample of pages and suggests the best set

⚠️ This project includes/links a BCH implementation derived from the Linux BCH code (GPL-2.0).
See License section below.

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Features

• ✅ Fix BCH errors in NAND dumps using a native BCH engine (DLL)
• ✅ Works on “adjacent RAW” dumps (PAGE + OOB repeated)
• ✅ Skips erased sectors (all 0xFF) to speed up processing
• ✅ Writes data-only output (PAGE bytes per page)
• ✅ Optional: write fixed RAW output
• ✅ Optional: recompute and rewrite ECC bytes in OOB
• ✅ Quick Test: suggests the best params (polynomial/transform/oobdata, and optionally swapBits/t depending on build)

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Supported input format

• RAW dump must be consecutive pages:
  • RAW_PAGE = PageSize + OobSize
  • File size must be a multiple of RAW_PAGE

Example (common Broadcom-like layout):

• PageSize = 2048
• OobSize = 64
• SectorSize = 512
• OobChunk = 16
• EccOfs = 9
• EccLen = 7
• Steps = PageSize / SectorSize = 4

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Build

Requirements

• Visual Studio 2022 (or newer)
• Desktop development with C++ (MSVC toolset)
• .NET 8 SDK
• Target: x64 (recommended)

Solution layout (typical)

• bchlib/ → native BCH library (C/C++ → bchlib.dll)
• NandDumpGUI/ → WPF app
• NandDumpGUI.Core/ → core logic (layout/fixer/quick test)
• NandDumpGUI.Native/ → P/Invoke wrappers (BchNative, BchContext, etc.)

Build steps

1. Build bchlib project (x64 Debug/Release) → produces bchlib.dll
2. Build NandDumpGUI (x64 Debug/Release)
3. Ensure bchlib.dll is copied into the WPF output folder:
   • NandDumpGUI/bin/x64/(Debug|Release)/net8.0-windows/

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Usage

1. Select Input RAW file (data+OOB interleaved)
2. Select Output data-only path
3. (Optional) enable Save fixed RAW and select output path
4. Configure:
   • Primitive polynomial (preset or manual)
   • t (error correction strength)
   • Transform mode
   • NAND layout parameters
   • OOB data bytes included in the BCH message (oobdata)
5. Click Start

Quick Test (recommended)

Click Quick Test to automatically try multiple parameter combinations on a sample of pages and suggest the best settings.
It’s useful when you don’t know the correct:

• primitive polynomial
• transform mode
• oobdata bytes
• (optionally) swapBits / candidate t values

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How to interpret results

The app reports:

• Total pages
• Checked sectors (non-erased)
• Uncorrectable sectors
• Pages modified
• Total corrected bitflips

Warning: “Fix may have failed”

If the uncorrectable ratio is high, it usually means:

• wrong polynomial
• wrong transform
• wrong layout (chunk offset/len, step size, etc.)
• dump is heavily corrupted/noisy

Suggestion: run Quick Test and/or verify the NAND layout.

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Tips / Troubleshooting

“bchlib.dll not found”

Make sure bchlib.dll is in the same folder as NandDumpGUI.exe:

• .../bin/x64/Debug/net8.0-windows/ (or Release)

Many uncorrectable sectors

Try:

• different transform (inv, bitrev, inv+bitrev)
• different primitive polynomial preset
• adjust oobdata (0..EccOfs)
• verify OobChunk, EccOfs, EccLen

RAW size not multiple of RAW_PAGE

Your dump might not be “adjacent raw pages” (or has headers/metadata).
You must provide a dump where each page is PageSize + OobSize.

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About

Created by Alessandro D’Alterio

• Email: [email protected]
• Website: alexxdal.com

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License

This project uses a BCH implementation derived from Linux BCH code (GPL-2.0).
If you distribute binaries that link this code, the resulting work is typically subject to GPL-2.0 requirements.

If you need a permissive-license alternative, you would need a clean-room BCH implementation or a differently-licensed BCH library.