TL;DR
The source summarizes three approaches for embedding files in C/C++: converting files with external tools (examples: ImageMagick, xxd), using the C preprocessor to turn ASCII files into string literals, and embedding raw data via inline assembly (.incbin into .rodata). Each method has trade-offs such as added build dependencies or platform-specific limitations.
What happened
The original write-up surveys common techniques for bundling resource files directly into C or C++ binaries. It notes that most workflows require converting resource files with external tools or scripts and gives two converter examples: ImageMagick for images and xxd with its -i switch for arbitrary files. For plain ASCII resources (such as shader sources) it describes a preprocessor pattern: define a STRINGIFY macro, place a string declaration, then include the external file wrapped in the macro so its contents become a string literal. Finally, the post shows an inline-assembly approach that emits an .incbin into the .rodata section and exposes start/end symbols (via macros that define incbin_name_start/end and extern pointers). The assembly example includes an INCBIN macro, an INCBIN(foobar,"binary.bin") invocation, and a sample main() printing start, end, size and the first byte. The author warns the ASM technique is platform-specific.
Why it matters
- Embedding resources removes a dependency on reading external files at runtime by placing data in the binary (as presented in the source).
- Using external converters can add build-time dependencies and steps to your build process (ImageMagick, xxd noted).
- The preprocessor route is suitable for plain ASCII resources and can be automated, but requires editing or wrapping the file before inclusion.
- The inline-assembly approach exposes raw data symbols for direct access but is platform-specific and may not work everywhere.
Key facts
- Article published 27 January 2013.
- External tool examples: ImageMagick command shown as: imagick input.png output.h.
- xxd example for arbitrary files: xxd -i input.whatever output.h.
- Preprocessor method uses a STRINGIFY macro (#define STRINGIFY(A) #A) and includes the external ASCII file wrapped so it becomes a C string literal.
- Preprocessor approach is presented as suitable for plain ASCII files (example: shaders) and requires editing the file to add the macro block, which is generally simple to automate.
- Assembly method uses an INCBIN macro that emits an .incbin into the .rodata section and defines global symbols incbin_<name>_start and incbin_<name>_end.
- Example shows INCBIN(foobar, "binary.bin") and a main() that prints the start and end addresses, size, and first byte of the embedded data.
- The ASM technique is explicitly noted as platform-specific and may not work on all platforms.
What to watch next
- Platform and toolchain compatibility when using the inline-assembly/.incbin approach (explicitly platform-specific in the source).
- Added build-time dependencies and steps if using external converters such as ImageMagick or xxd (shown in examples).
- Impact on binary size and runtime memory usage: not confirmed in the source.
Quick glossary
- preprocessor: A phase of compilation that processes directives beginning with #, allowing macros, file inclusion, and conditional compilation before actual compilation.
- inline assembly (__asm__): Compiler-supported syntax to embed assembly instructions or directives directly within C/C++ source code.
- .rodata: A read-only data section in many object formats where constant data (such as string literals) is stored in the final binary.
- xxd -i: A mode of the xxd utility that converts binary data into a C include file (an array initializer), suitable for embedding in source.
- ImageMagick (imagick): A suite of image-processing tools that can convert and manipulate images; here shown producing a .h include file from an image.
Reader FAQ
Do these methods require converting files first?
The source states that in most cases you must convert files with external tools or scripts.
Is the preprocessor method suitable for binary files?
The source indicates the preprocessor approach is intended for plain ASCII files (eg. shaders), not arbitrary binary files.
Is the inline-assembly (.incbin) approach portable?
No — the write-up explicitly says the ASM method is platform-specific and will not work on all platforms.
Can the preprocessor wrapping be automated?
The source says the operation is rudimentary and usually relatively simple to automate.
C/C++ EMBEDDED FILES PUBLISHED: 27 JANUARY 2013 A summary of different approaches for embedding files within c / c++ code TABLE OF CONTENTS Using external tools Using the preprocessor Using…
Sources
- C/C++ Embedded Files
- Embedding resources in executable using GCC – c++
- How to Embed Binary Data into a Win32 Executable File in …
- How to embed data files into C/C++ executable
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