Intel Corporation

International Business Machines Corporation

Mark D Atkins

Robert W Adams

Agnes Yee Ngai

Alfred T Rundle

Jens Bodenkamp

Method and apparatus to avoid the code space and time overhead of the software-loop. Loops (repeatedly executed blocks of instructions) are often used in software and microcode. Loops may be employed for array manipulation, storage initialization, division and square-root interpretation, and microinterpretation of instructions with variable-length operands. Software creates loops by keeping an iteration count in a register or in memory. During each iteration of the code loop, software decrements the count, and then branches to the 'top' of the loop is the count remains nonzero. This apparatus puts the decrement, compare, and branch-to-top into hardware, reducing the number of instructions in the loop and speeding loop execution. Hardware further speeds loop execution by eliminating the wait for the branch to the top-of-loop instruction. That is, it prefetches the top-of-loop instruction near the bottom of the loop. The loop may be initialized for a fixed iteration count, or can accept a variable count in the iteration count register. The apparatus consists of counters for the number of instructions in the loop, an iteration counter, a pointer to the top-of-loop location, and an instruction to initiate the loop.

Method and apparatus for counting remaining loop instructions and

A method and apparatus for generating a composite image from multiple source images using multiple local masks. Each source image is generated by an image generator. Each image generator has a local mask that indicates which pixels of the source image are to be transmitted to a frame buffer. The local mask may also be used to indicate which pixels of the source image are to be updated by the image generator.

Method and apparatus for generating composite images using multiple

A CPU or other graphics processor provides a pixel data stream to a graphics controller over a system bus. The pixel data stream includes a graphics controller address as well as a pixel type tag, which in the presently preferred embodiment comprises 4 bits. In addition to the graphic controller address and pixel type tag, a pixel address and pixel data are provided. The pixel type tag identifies the 'type' of pixel data in the data stream supplied to the graphics controller. If the data identified by the pixel type tag corresponds to the type of data which the frame buffer is configured for, then the data provided over the system bus is simply passed through the graphics controller and written at the appropriate pixel address in the frame buffer. If, however, the pixel type tag indicates that the data is not of the same type as that for which the frame buffer is configured, then the graphic controller executes a conversion algorithm to convert the pixel data to a single pixel type acceptable to the frame buffer, and the data is then written into the frame buffer at the pixel address identified by the pixel address. Pixel type tagging is accomplished, in the preferred embodiment, in bits 27:24 of the physical address used to write pixels into the frame buffer. The CPU, or other graphics engine source, affixes the tag to the pixel data, thereby identifying its format. In the present embodiment, MDA tagging applies only to pixel write commands and not to commands reading from the frame buffer. Accordingly, the use of a pixel type tag field in the pixel data permits a graphics system to utilize a variety of standard pixel types by a CPU, graphics controller or other graphics source, while permitting the frame buffer to utilize a single pixel type to be stored in the frame buffer for subsequent display.

Method and apparatus for address space aliasing to identify pixel types

An enhanced single frame buffer video display system is described for combining both video and graphical images. A single frame buffer is implemented which stores a single data format for pixel types which may be interpreted by a conventional video generator for output to conventional color graphics computer display devices. The system utilizes an enhanced graphics controller which does all pixel processing for translating all incoming graphics and video data to a single format type as well as performing, blending and scaling. The system is readily scalable for handling additional format data types.

Growing community of inventors

Santa Clara, CA, United States of America

Mark D Atkins