Patent ID: 6801219
Filing Date: 2004-10-05
Classification: G09G

Abstract:
A method for buffering a subset of digital image data used to drive a scrolling display, the method comprising the steps of:storing a first contiguous data subset of a complete set of digital image data into a buffer memory, the data subset being greater than an amount of data accessed by a display and the buffer memory being organized as a two dimensional circular buffer; determining if a display buffer within the first contiguous data subset is within a threshold distance of an edge of data forming the first contiguous data subset; identifying an additional subset of the complete set of digital image data to place into the buffer memory, wherein the additional subset is image data that is contiguous with the first contiguous data and wherein the additional subset of data extends beyond the edge of the first contiguous data subset; and loading the additional subset of data into the display buffer beyond the edge of the first contiguous data subset through circular addressing of the display buffer, wherein the buffer memory stores a plurality of pixels, each of the plurality of pixels having a pixel address within the buffer memory, wherein each pixel is characterized by a row position and a row number, and wherein the buffer memory is characterized by a row length and a data buffer size, wherein a selected pixel is access by: calculating a row offset within the buffer memory by multiplying a row number of the selected pixel by the row length; adding a buffer memory starting data address, modulo the data buffer size, to a selected row position of the selected pixel, and adding that sum to the row offset; and subtracting the data buffer size from the row offset if the row offset is greater than the data buffer size.