发明公开
- 专利标题: Leading 0/1 anticipator (LZA)
- 专利标题(中): LEADING 0/1预感(显示)
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申请号: EP89116899.9申请日: 1989-09-13
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公开(公告)号: EP0362580A3公开(公告)日: 1991-10-30
- 发明人: Hokenek, Erdem , Montoye, Robert Kevin
- 申请人: International Business Machines Corporation
- 申请人地址: Old Orchard Road Armonk, N.Y. 10504 US
- 专利权人: International Business Machines Corporation
- 当前专利权人: International Business Machines Corporation
- 当前专利权人地址: Old Orchard Road Armonk, N.Y. 10504 US
- 代理机构: Schäfer, Wolfgang, Dipl.-Ing.
- 优先权: US255089 19881007
- 主分类号: G06F5/01
- IPC分类号: G06F5/01 ; G06F7/48
摘要:
A method and system are disclosed for performing a leading 0/1 anticipation (LZA) in parallel with the floating-point addition of two operands (A and B) in a computer to significantly reduce the Addition-Normalization time. A combinational network is used to process appropriate XOR (P), AND (G), and NOR (Z) state signals resulting from the comparison of the bits in corresponding bit positions of the operands (A and B), starting with the most significant bit (MSB) side of the addition. The state of the initial state signal is detected and shift amount signals are produced and counted for each successive state signal detected, as long as the state remains TRUE. When the state becomes NOT TRUE, adjustments are made depending on the initial state and the successive state, and production of the shift amount signals is halted and an adjustment signal is produced. To determine the exponent of the sum of the floating-point addition, the shift amount count is summed with the adjustment signal. The latter sum will be the exponent of the sum of the operands thus providing a normalized result. The adjustment signal may be based on the CARRY at the NOT TRUE bit position, and the state at the NOT TRUE position may be used to determine whether the result of the addition is positive or negative. In addition to a serial network, an implementing network of a parallel form which accepts appropriate state inputs as blocks of n bits in length, is disclosed, along with certain special implementation.
公开/授权文献
- EP0362580B1 Leading 0/1 anticipator (LZA) 公开/授权日:1996-04-24
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