| 摘要 |
A method for determining, by means of a circuit, a result s<SUB>k+2 </SUB>of an operation of the type <maths id="MATH-US-00001" num="00001"> <MATH OVERFLOW="SCROLL"> <MROW> <MSUB> <MI>s</MI> <MROW> <MI>k</MI> <MO>+</MO> <MN>2</MN> </MROW> </MSUB> <MO>=</MO> <MROW> <MROW> <MO>(</MO> <MROW> <MSUB> <MI>s</MI> <MI>k</MI> </MSUB> <MO></MO> <MUNDER> <MO>+</MO> <MI>.</MI> </MUNDER> <MO></MO> <MSUB> <MI>a</MI> <MI>k</MI> </MSUB> </MROW> <MO>)</MO> </MROW> <MO></MO> <MUNDER> <MO>+</MO> <MI>.</MI> </MUNDER> <MO></MO> <MSUB> <MI>a</MI> <MROW> <MI>k</MI> <MO>+</MO> <MN>1</MN> </MROW> </MSUB> </MROW> </MROW> </MATH> </MATHS> where s<SUB>k</SUB>, a<SUB>k</SUB>, and a<SUB>k+1 </SUB>are fractional signed operands and symbol <maths id="MATH-US-00002" num="00002"> <MATH OVERFLOW="SCROLL"> <MUNDER> <MO>+</MO> <MI>.</MI> </MUNDER> </MATH> </MATHS> represents a saturating addition operation, comprising: a step of calculation of three sums representative of a possible value of the result, and a step of selection of one of said three sums according to overflows having occurred in the sum calculation. At least one step of the method uses the positive part and the negative part of at least one of the operands.
|
