# x86inc.asm

> abstraction layer for writing x86 assembly

**Wikidata**: [Q117825350](https://www.wikidata.org/wiki/Q117825350)  
**Source**: https://4ort.xyz/entity/x86inc-asm

## Summary
x86inc.asm is an abstraction layer designed to simplify writing x86 assembly code, particularly for SIMD (Single Instruction, Multiple Data) operations, and is used as a header file by various multimedia and video processing software projects.

## Key Facts
- x86inc.asm was published in 2005 and is maintained under the ISC license.
- It was created by Loren Merritt, Henrik Gramner, Anton Mitrofanov, and Fiona Glaser.
- The abstraction layer is written in x86 assembly language and serves as a header file.
- It functions as an abstraction layer for writing x86 assembly code.
- The source code repository is hosted at https://code.videolan.org/videolan/x86inc.asm.git.
- It is copyrighted software used by multiple video processing libraries including x264, x265, libvpx, and FFmpeg.

## FAQs
### Q: What is x86inc.asm used for?
A: It serves as an abstraction layer to simplify writing x86 assembly code, particularly for SIMD operations in multimedia and video processing applications.

### Q: Which software projects use x86inc.asm?
A: It is used by various video processing libraries including x264, x265, libvpx, libaom, rav1e, dav1d, FFmpeg, kvazaar, and libass.

### Q: What is the license under which x86inc.asm is distributed?
A: It is distributed under the ISC license.

## Why It Matters
x86inc.asm represents an important abstraction layer that simplifies the complex task of writing optimized x86 assembly code, particularly for SIMD operations. By providing a standardized interface and pre-written assembly functions, it helps developers create highly optimized multimedia processing software without needing to write raw assembly code from scratch. This abstraction layer has become a de facto standard in the video processing community, enabling consistent performance across different x86 architectures and compilers. Its impact is evident in the widespread adoption by major open-source multimedia projects, where it contributes to significant performance improvements in video encoding and decoding operations.

## Notable For
- It provides a standardized abstraction layer that simplifies writing optimized x86 assembly code for SIMD operations.
- It has become a de facto standard in the video processing community, used by multiple major open-source projects.
- The abstraction layer helps developers achieve high performance without needing to write raw assembly code from scratch.
- It supports various x86 architectures and compilers through a consistent interface.
- It has been maintained and improved by multiple contributors over the years, with the original authors being Loren Merritt, Henrik Gramner, Anton Mitrofanov, and Fiona Glaser.

## Body
### Development and Maintenance
x86inc.asm was first published in 2005 and has since been maintained as an open-source project. The source code is hosted at https://code.videolan.org/videolan/x86inc.asm.git. The project is copyrighted software distributed under the ISC license.

### Technical Approach
The abstraction layer provides a header file containing pre-written assembly functions that implement common SIMD operations. This approach allows developers to call these functions directly from their C or C++ code, rather than writing assembly code manually. The functions are optimized for different x86 processor families and instruction sets, including SSE, SSE2, SSE3, SSSE3, SSE4, and AVX.

### Usage in Multimedia Projects
The abstraction layer has been adopted by numerous video processing libraries, including:
- x264 (video encoder)
- x265 (video encoder)
- libvpx (video codec)
- libaom (video codec)
- rav1e (video codec)
- dav1d (video decoder)
- FFmpeg (multimedia framework)
- kvazaar (video encoder)
- libass (subtitles rendering)

These projects use x86inc.asm to implement highly optimized assembly routines that accelerate video processing tasks such as compression, decompression, and filtering operations. The consistent interface provided by x86inc.asm helps maintain code quality and performance across different platforms and compiler versions.

### Technical Features
The abstraction layer includes functions for various operations such as:
- Integer and floating-point arithmetic
- Bit manipulation
- Memory operations
- SIMD-specific operations
- Various multimedia processing functions

Each function is carefully optimized for different processor families and instruction sets, ensuring maximum performance on the target hardware. The abstraction layer also provides compatibility across different compilers and operating systems.

### Evolution and Community
Since its initial release, x86inc.asm has evolved through contributions from various developers in the multimedia community. The project has maintained compatibility with newer processor architectures and instruction sets while preserving backward compatibility with older systems. The open-source nature of the project has allowed for continuous improvement and adaptation to emerging hardware technologies.

## References

1. [Source](https://code.videolan.org/videolan/x86inc.asm/-/blob/master/x86inc.asm)
2. [Source](https://code.videolan.org/videolan/x264/-/blob/master/common/x86/x86inc.asm)
3. [Source](https://bitbucket.org/multicoreware/x265_git/src/master/source/common/x86/x86inc.asm)
4. [Source](https://chromium.googlesource.com/webm/libvpx.git/+/refs/heads/main/third_party/x86inc/)
5. [Source](https://aomedia.googlesource.com/aom/+/refs/heads/main/third_party/x86inc/)
6. [Source](https://github.com/xiph/rav1e/blob/master/src/ext/x86/x86inc.asm)
7. [Source](https://code.videolan.org/videolan/dav1d/-/blob/master/src/ext/x86/x86inc.asm)
8. [Source](https://gitlab.com/AOMediaCodec/SVT-AV1/-/blob/master/Source/Lib/Common/ASM_AVX2/dav1d_x86inc.asm?ref_type=heads)
9. [Source](https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/HEAD:/libavutil/x86/x86inc.asm)
10. [Source](https://github.com/ultravideo/kvazaar/blob/7856583ee05f627bbab153bedb68d586ccb3750d/LICENSE.EXT.x264asm)
11. [Source](https://github.com/libass/libass/blob/master/libass/x86/x86inc.asm)
12. [Source](https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/subprojects/gst-plugins-good/gst/deinterlace/x86/x86inc.asm?ref_type=heads)