| 摘要 |
<p>PURPOSE:To realize a hardware clipping operation by comparing a decomposed clipping area parameter with the executing X and Y addresses produced by a drawing processor. CONSTITUTION:The clipping area of an active window is decomposed into a rectangular area based on the contents of plural clip registers 11. Then the decomposition parameters are stored in the clip registers 13 and 14. An executing X address outputted from a drawing processor 18 is compared with the clip X start-end address of the register 14 by an X comparator 16. While an executing Y address outputted from the processor 8 is compared with a set of the intersecting point Y addresses held by the register 13 by a Y comparator respectively. Based on the obtained decomposed rectangular area information, a signal Xsel is outputted to designate a Y start-end set. The processor 18 decides whether a drawing operation should be carried out or not by the output signals CX and CY and then outputs the executing control information.</p> |
