PRIORITY ENCODER

PURPOSE:To attain a regular layout of circuits, to reduce the increase of the computing time to the increase of the number of bits, and to improve the bit extension properties by forming a multi-bit priority encoder in a tree shape. CONSTITUTION:The multi-bit data are divided into blocks and the preceding '0' or '1' is retrieved from the highest position of each block. Then the detected bit position is encoded and outputted for output of an absence signal that shows the presence or absence of a retrieving subject. For these purposes, the 1st detector means 1 and 2 are provided. Meanwhile the 2nd detector means 3 - 6 retrieve the absence signal as a subject and then encodes and outputs the detected block positions. Furthermore the logic circuits 7 - 16 are added to generate the encoding output serving as a part of the encoding result of the multi-bit data from the absence signal and the encoding output. The continuous absence signals of the means 3 - 6 are inputted to the means 3 - 6. Then a tree-shaped constitution is formed so that the outputs of the circuits 7 - 16 can serve as the inputs of the circuits 7 - 16 of the next stage. In such a constitution, the preceding '1' or '0' of the multi-bit data can be detected at a high speed.