Invention Grant
- Patent Title: Decimal floating point mechanism and process of multiplication without resultant leading zero detection
- Patent Title (中): 十进制浮点机制和乘法处理,而没有得到前导零检测
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Application No.: US12821648Application Date: 2010-06-23
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Publication No.: US08495124B2Publication Date: 2013-07-23
- Inventor: Steven R. Carlough , Adam B. Collura , Michael Kroener , Silvia Melitta Mueller
- Applicant: Steven R. Carlough , Adam B. Collura , Michael Kroener , Silvia Melitta Mueller
- Applicant Address: US NY Armonk
- Assignee: International Business Machines Corporation
- Current Assignee: International Business Machines Corporation
- Current Assignee Address: US NY Armonk
- Agent John E. Campbell
- Main IPC: G06F7/52
- IPC: G06F7/52

Abstract:
A decimal multiplication mechanism for fixed and floating point computation in a computer having a coefficient mechanism without resulting leading zero detection (LZD) and process which assumes that the final product will be M+N digits in length and performs all calculations based on this assumption. Least significant digits that would be truncated are no longer stored, but retained as sticky information which is used to finalize the result product. Once the computation of the product is complete, a final check based on the examination of key bits observed during partial product accumulation is used to determine if the final product is truly M+N digits in length, or M+N−1 digits. If the latter is true, then corrective final product shifting is employed to obtain the proper result. This eliminates the need for dedicated leading zero detection hardware used to determine the number of significant digits in the final product. The corrective final product shifting also incorporates adjustments to the coefficient of the product when the product's exponent is at its extremes and the final product must be brought to be within the precision and range of a given format.
Public/Granted literature
- US20110320512A1 Decimal Floating Point Mechanism and Process of Multiplication without Resultant Leading Zero Detection Public/Granted day:2011-12-29
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