发明授权
US6094668A Floating point arithmetic unit including an efficient close data path
失效
浮点运算单元包括有效的关闭数据路径
- 专利标题: Floating point arithmetic unit including an efficient close data path
- 专利标题(中): 浮点运算单元包括有效的关闭数据路径
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申请号: US49893申请日: 1998-03-27
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公开(公告)号: US6094668A公开(公告)日: 2000-07-25
- 发明人: Stuart F. Oberman
- 申请人: Stuart F. Oberman
- 申请人地址: CA Sunnyvale
- 专利权人: Advanced Micro Devices, Inc.
- 当前专利权人: Advanced Micro Devices, Inc.
- 当前专利权人地址: CA Sunnyvale
- 主分类号: G06F7/57
- IPC分类号: G06F7/57 ; G06F9/30 ; G06F9/302 ; G06F9/318 ; G06F9/38 ; H03M7/24 ; G06F7/42
摘要:
An execution unit configured to execute vectored floating point and integer instructions. The execution unit may include an add/subtract pipeline having far and close data paths. The far data path is configured to handle effective addition operations, as well as effective subtraction operations for operands having an absolute exponent difference greater than one. The close data path is configured to handle effective subtraction operations for operands having an absolute exponent difference less than or equal to one. The close data path includes an adder unit configured to generate a first and second output value. The first output value is equal to the first input operand plus an inverted version of the second input operand, while the second output value is equal to the first output value plus one. The two output values are conveyed to a multiplexer unit, which selects one of the output values as a preliminary subtraction result based on a final selection signal received from a selection unit. The selection unit generates the final selection signal from a plurality of preliminary selection signals based on the carry in signal to the most significant bit of the first adder output value. Selection of the first or second output value in the close data path effectuates the round-to-nearest operation.
公开/授权文献
- USD396808S Container 公开/授权日:1998-08-11
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