A logical step in the shift toward IP-based GPU solutions is the emergence of efficient, small footprint software OpenGL implementations. The Gerbera rasterizer from Hybrid Graphics was an early OpenGL ES software implementation. The display rendering for such airliners as the A380 employs software-based rendering. For safety critical systems, Quantum3D's IGL 178 is the latest software GPU to be released. IGL is a COTS DO-178B certifiable software implementation of OpenGL SC that is optimized for fast execution, image quality, and flexible integration into special-purpose applications.

The case for employing a software GPU is easy to make. Software provides natural resistance to obsolescence. New multicore and reconfigurable processor array technologies are designed to offer increased capabilities to general-purpose software applications. A software GPU can offer unmatched flexibility due to the ease of making changes. The main benefit to using a software GPU is that a consistent API can be used to enable OpenGL applications to run on all classes of target systems. An application making limited graphical demands on the system, such as a standby instrument, soft controller, or video overlay rendering, need not require an expensive GPU to deploy (Figure 3).

A high percentage of embedded graphics displays can be rendered without hardware acceleration, provided the rendering software is efficiently implemented. IGL 178 was developed to address these types of applications. IGL's feature set includes:

• Full OpenGL SC functionality enabling IGL applications upward compatibility with accelerated GPUs.

• Optional virtualized driver enabling a standard processor to function as a dedicated GPU in the system.

• Efficient high-performance implementation, supporting both floating and fixed point math and fast paths for common safety critical uses.

• Complete, tailorable source code usable in any operating system.

• Small, implementation certifiable to safety standards, including DO-178B.

• High quality anti-aliased lines and textures at all display resolutions.

• Support for 16, 24, and 32 bit frame buffer modes, with or without alpha-out.

• Rendering using a user-supplied frame buffer to accomplish video blend, static symbology backgrounds, and other special-purpose features.

GPUs are valuable but challenging components of almost all embedded systems that render a display. Their promise is fast, standards-based processing of display data. Newer GPU choices, such as IP cores, and software implementations, are coming on to the market to offer systems designers more choices. Software standardization is a key that can allow applications to make best use of all forms of GPUs.

Mark Snyder is a senior engineering manager with Quantum3D, Inc, where his responsibilities include research, development, and technical management of software and development tools for safety critical and high-reliability embedded graphics displays. While at Quantum3D, Snyder has been a key developer of several core technologies, including Quantum3D's COTS IData embedded application engine and IGL 178 software GPU. Prior to joining Quantum3D, he was employed with Honeywell International as an engineer developing advanced navigation, situational awareness and synthetic vision systems for DO178B certified business jet glass flight decks. Snyder also spent 9 years as an Air Force Officer, where he was involved in 3-D virtual simulation and visualization research at the Air Force Research Lab and engineered C4ISR systems at Air Force Space Command. He holds a BS from Arizona State University and an MS from the Air Force Institute of Technology, and is inventor on several patents in the avionics flight deck display arena.

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