Method and apparatus for color space conversion, clipping, and scaling of an image during blitting

A method for performing blitter operations to transfer data corresponding to pixels of a source image to a target buffer for holding data for a target image to be displayed on a monitor, the blitter operation being defined by a blitter description, which includes information describing sizes of the source and target images, color formats of the source and target images, and further describes the target image in terms of at least one visible rectangle, the method comprising the steps of:

• modifying the blitter description;
• creating a line-type description of the target image from the visible rectangle description of the target image, the line-type description comprising at least one run of pixels defined by visible and non-visible pixel states, the line-type description further comprising a repeat count indicating the number of lines of the target image corresponding to the line-type description;
• generating a machine code sequence to be associated with the line-type description, the machine code sequence including machine code instructions to move and process data that are defined by visible runs of the line type description;
• and
• executing the machine code sequence, in accordance with the line-type description, the machine code sequence being invoked a number of times equal to the repeat count of the line-type description so as to transfer the data corresponding to the pixels of a source image to the target buffer in accordance with the modified blitter description during the blitter operation.

A computer program product for performing blitter operations to transfer data corresponding to pixels of a source image to a target buffer for holding data for a target image to be displayed on a monitor, the blitter operation being defined by a blitter description, which includes information describing sizes of the source and target images, color formats of the source and target images, and further describes the target image in terms of at least one visible rectangle, the computer program product comprising:

• computer usable medium having computer readable program code embodied therein;
• program code embodied within said computer usable medium, for creating a line-type description of the target image from the visible rectangle description of the target image, the line-type description comprising at least one run of pixels defined by visible and non-visible pixel states, the line-type description further comprising a repeat count indicating the number of lines of the target image corresponding to the line-type description;
• program code embodied within said computer usable medium, for generating a machine code sequence to be associated with the line-type description, the machine code sequence including machine code instructions to move and process data that are defined by visible runs of the line type description;
• and
• program code embodied within said computer usable medium, for executing the machine code sequence, in accordance with the line-type description, the machine code sequence being invoked a number of times equal to the repeat count of the line-type description so as to transfer the data corresponding to the pixels of a source image to the target buffer in accordance with the modified blitter description during the blitter operation.