SHIFT QUANTITY CALCULATING DEVICE FOR BIT MAP DISPLAY DEVICE

摘要

PURPOSE:To calculate the shift quantity data in a short time by using the difference between addresses of two areas as two types of the difference data and outputting one of both difference data based on a selection signal as well as the difference of address values at the 16-bit boundaries between both data. CONSTITUTION:A difference calculation means supplies the addresses of two processing subject areas of the picture data which undergoes the arithmetic processing for each rectangular area on a display screen and performs the switch between a subtrahend and a minuend to calculate the difference between both addresses as the difference data of two types. A selection control means outputs a mode selecting signal based on the code output of one of both difference data. The combination conditions on the two types of data are selected by controlling a calculation mode selection means based on the mode selecting signal. Then an output selection means is controlled based on the output selecting signal supplied from the outside so that one of both data is selected and outputted as the shift quantity data.