公开(公告)号：JPH08110853A

公开(公告)日：1996-04-30

申请号：JP26637495

申请日：1995-09-20

Applicant: XILINX INC

Inventor： BAANAADO JIEI NIYUU ,  KERII EMU PIAASU

IPC: G06F7/38 ,  G06F7/00 ,  G06F7/50 ,  G06F7/503 ,  G06F7/506 ,  G06F7/507 ,  G06F7/57 ,  H03K19/173 ,  H03K19/177

Abstract: PROBLEM TO BE SOLVED: To provide a programmable logic circuit equipped with a circuit which has a logic block having flexibility in circuit configuration and implements high-speed carry logic. SOLUTION: A programmable logic device in which a plurality of blocks of combinational function generators and storing elements are connected to each other in a programmable interconnecting structure is frequently used for arithmetic operation using carry function generating logic. When processing of many bits is required, a carry function is usually delayed remarkably and a large number of additional elements is required for obtaining results at a high speed. Therefore, hardware exclusively used for executing the carry function at a high speed with the smallest number of elements is provided in a logic block. This circuit is provided with an additional circuit so that the hardware for the high-speed carry function can implement the other conventional functions.