Memory management system and method

摘要

There is provided a method and apparatus for managing memory in a system for generating 3-dimensional computer images. The image is subdivided into a plurality of rectangular areas. A memory is provided and a page of the memory is allocated for storing object data for objects in the image. Object data for objects in the image are then written to the allocated page of memory. Finally, a bit mask for the allocated page of memory is compiled, the bit mask indicating the rectangular areas having object data stored in the allocated page of memory. A rectangular area of the image can then be rendered by deriving data for display from the object data stored in the memory, for objects in that rectangular area. Once the rectangular area has been rendered, the bit mask for each page of memory which stored, before the step of rendering, object data for that rectangular area, is updated so that the bit mask no longer indicates that rectangular area.

主权项

1. A method for managing memory allocation in a 3D graphics system, the method comprising the steps of:
subdividing an image to be rendered into a plurality of rectangular areas; allocating memory pages to store data defining objects to be rendered; storing data defining objects to be rendered in the allocated memory pages; allocating an object list for each rectangular area, the object list comprising data identifying locations in the memory pages allocated to store the data defining objects that overlap that rectangular area; dynamically allocating memory pages to each object list as the object list is compiled; storing a bit mask for each memory page allocated to store data defining objects to be rendered, the bit mask comprising data identifying all of the rectangular areas that are overlapped by objects having data stored in that page of memory; determining when a number of free pages of memory falls below a predetermined limit; determining which rectangular areas need to be rendered to free at least some of the pages of memory by referencing the stored bit masks; rendering at least one rectangular area so determined; and adding any pages of memory freed by the rendering step to a free memory list.