METHOD AND APPARATUS FOR HIGH-SPEED BLOCK TRANSFER OF COMPRESSED AND WORD-ALIGNED BITMAPS

摘要

Graphics display is performed by compressing pixel information, by aligning the 8, 16, or 32 bit pixels transferred over a 32-bit Peripheral Component Interface (PCI) bus (609) with the pixels in the display memory (612), and by avoiding moves of pixel data within display memory (612). Compression is achieved by not transferring data for pixels that are not modified by the transfer. Rather, a count of unmodified pixel bytes to skip precedes each set of pixel data for contiguous pixels that are modified. Alignment is achieved by ensuring that the boundaries between words within the pixel set transferred matches those within the corresponding target pixels in the display memory (612). This alignment significantly speeds up modifying pixel data within the display memory (612). The burden of ensuring this alignment is placed on the applications software that initiates the transfer.