| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption by processing write at high speed without rewrite when write is performed by superposing a plurality of sprites on a frame memory. SOLUTION: When writing is performed by superposing sprites 1, 2 on the frame memory, the front sprite 1 is written and the sprite 2 is written in the back of the sprite 1 on the contrary to the conventional case. In a scan line j, eight pixels are defined as one block. Addresses XL<SB>-</SB>1 to XRS<SB>-</SB>1 are display parts of the sprite 1, addresses XLS<SB>-</SB>2 to XRS<SB>-</SB>2 are display parts of the sprite 2, and other parts are transparent. In addition, a mask memory in which one bit is written by every pixel is prepared. Whether or not the display parts of the sprite 1 is detected for the respective pixels in the block, a bit string in which detection results are expressed by one bit by every pixel is outputted, a bit string obtained by performing an arithmetic operation between the bit string and a bit string of the mask memory is obtained, write of sprite data in the frame memory is controlled by using the bit string and the mask memory is updated. These processes are similarly performed for the sprite 2. COPYRIGHT: (C)2004,JPO |
