Pixel component packing, unpacking, and modification

• US 6,452,601 B1
• Filed: 05/20/1999
• Issued: 09/17/2002
• Est. Priority Date: 05/20/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Marino, Richard Anthony, Van Nostrand, Mark Ernest
• Primary Examiner(s): Tung, Kee M.
• Application Number:
  US09/315,544
• Time in Patent Office: 1,216 Days
• Field of Search: 345/501, 345/520, 345/537, 345/538, 345/546, 345/559, 345/545, 345/561, 345/562, 345/600, 345/603-605, 710/124-129, 711/202
• US Class Current: 345/538
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units
• CPC Class Codes: G06T 17/00 Three dimensional [3D] modelling, e.g. data description of 3D objects
• CPC Class Codes: G06T 2210/32 Image data format
• CPC Class Codes: G09G 5/363 Graphics controllers

Abstract

A computer system and an associated graphics adapter that includes one or more processors connected to a host bus. A system memory is accessible from the host bus via a memory controller and an I/O bridge is coupled between the host bus and an I/O bus. The computer system further includes a frame buffer suitable for storing a representation of a graphic image and the graphics adapter connected to the I/O bus. The graphics adapter includes means for receiving host pixel data that is formatted, according to a host format defining the ordering and width of a set host components, as a set of host component values. The adapter also has means for transforming the host pixel data into frame buffer pixel data where the frame buffer pixel data is formatted, according to a frame buffer format defining the ordering and width of a set of frame buffer components, as a set of frame buffer component values. In the preferred embodiment, the value of each host pixel data component is replicated in a corresponding component of the frame buffer pixel data by repeating the bits comprising the value in the corresponding frame buffer component until the frame buffer component is full. In the preferred embodiment, the transforming means includes a programmable set of host format definition registers that define the host format. These registers preferably include a start bit register and a width register for each component of the data. The component data widths are permitted to vary from one another in the preferred embodiment such that a first component of the host pixel data could have one width an a second component could have another (different) width. The adapter preferably further includes means for scaling and biasing the frame buffer pixel data and means for transforming (packing) frame buffer pixel data into host pixel data.

Claims

1. A computer system comprising:

a system memory accessible from the host bus via a memory controller;

an I/O bridge coupled between the host bus and the I/O bus;

a frame buffer suitable for storing a representation of a graphic image; and

a graphics adapter on the I/O bus, wherein the graphics adapter comprises

register means for programmably specifying a host pixel data format that defines the ordering and width of a set of host components;

means for receiving host pixel data comprising a set of host component values formatted according to the host pixel data format;

means for transforming the host pixel data into frame buffer pixel data formatted, according to a frame buffer format defining the ordering and width of a set of frame buffer components, as a set of frame buffer component values; and

means for forwarding the frame buffer pixel data to the frame buffer.

2. The computer system of claim 1, wherein the width of a host component is less than the width of the corresponding frame buffer component and wherein the transformation means derive a value for the frame buffer component from the host component value by appending replicates of the bit string comprising the host component value to the host component value until the bit-width of the resulting bit string equals or exceeds the width of the frame buffer component.

3. The computer system of claim 1, wherein the programmable specification means comprises a host format definition register having a set of fields corresponding to each host component wherein values in the host format definition register fields define the host format.

4. The computer system of claim 3, wherein the host format definition register includes a start bit field and a width field for each component of the frame buffer format.

5. The computer system of claim 1, further comprising facilities to accommodate screen-to-system pixel transfers and screen-to-screen pixel transfers utilizing the transforming means.

6. The computer system of claim 1, wherein the programmable specification means permits the width of a first host component to differ from the width of a second host component.

7. The computer system of claim 1, wherein the components of the frame buffer format each have equal width.

8. The computer system of claim 1, further comprising means for scaling and biasing the frame buffer pixel data.

9. The computer system of claim 1, further comprising means for transforming frame buffer pixel data to host pixel data and means for forwarding the host pixel data back to the host.

10. A graphics adapter comprising:

register means for programmably specifying a host pixel data format that defines the ordering and width of a set of host components;

means for receiving host pixel data comprising a set of host component values formatted according to the host pixel data format;

means for transforming the host pixel data into frame buffer pixel data formatted, according to a frame buffer format defining the ordering and width of a set of frame buffer components, as a set of frame buffer component values, wherein the transforming means support any host format in which the set of host components is equal to or a subset of the set of frame buffer components and the width of each host component is less than or equal to the width of the corresponding frame buffer component; and

means for forwarding the frame buffer pixel data to a frame buffer.

11. The graphics adapter of claim 10, wherein the width of a host component is less than the width of the corresponding frame buffer component and wherein the transformation means derive a value for the frame buffer component from the host component value by appending replicates of the bit string comprising the host component value to the host component value until the bit-width of the resulting bit string equals or exceeds the width of the frame buffer component.

12. The graphics adapter of claim 10, wherein the programmable specification means comprises a host format definition register having a set of fields corresponding to each host component wherein values in the host format definition register fields define the host format.

13. The graphics adapter of claim 12, wherein the host format definition register includes a start bit field and a width field for each component of the frame buffer format.

14. The graphics adapter of claim 10, wherein the host format permits any component width less than or equal to 8.

15. The graphics adapter of claim 10, wherein the host format permits the width of a first host component to differ from the width of a second host component.

16. The graphics adapter of claim 10, wherein the components of the frame buffer format each have equal width.

17. The graphics adapter of claim 10, further comprising means for scaling and biasing the frame buffer pixel data.

18. The graphics adapter of claim 10, further comprising means for transforming frame buffer pixel data to host pixel data and means for forwarding the host pixel data back to the host.

19. A method of processing pixels, comprising:

providing register means for programmably specifying a host pixel data format from that defines the ordering and width of a set of host components;

receiving host pixel data comprising a set of host component values formatted according to the host pixel data format;

transforming the host pixel data to frame buffer pixel data formatted, according to a frame buffer format defining the ordering and width of the frame buffer components, as a set of frame buffer component values wherein the transforming accommodates any host format in which the set of host components is equal to or a subset of the set of frame buffer components and the width of each host component is less than or equal to the width of a corresponding frame buffer component; and

forwarding the frame buffer pixel data to a frame buffer.

20. The method of claim 19, wherein the step of transforming includes deriving a value for the frame buffer component from the host component value by appending replicates of the bit string comprising the host component value until the bit-width of the resulting bit string equals or exceeds the width of the frame buffer component.

21. The method of claim 19, wherein the step of transforming includes programming a set of host format definition registers prior to receiving the host pixel data, wherein values of the host format definition registers define the host format.

22. The method of claim 19, further comprising scaling and biasing the frame buffer pixel data.

23. The method of claim 19, further comprising transforming frame buffer pixel data to host pixel data and forwarding the host pixel data back to the host.