| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-speed multiplication computing digital circuit for complying with a requirement for high-speed data processing, which is necessary in development of a portable terminal, for computing processing by an RISC CPU mounted in the portable terminal. <P>SOLUTION: A circuit shown in the figure is constructed of a barrel shifter outputting an input signal A[n-1:0], SH [log<SB>2</SB>n-1:0], DAT [n-1:0], and data B [n-1:0] in which the signal DAT is shifted by the signal SH bits, a group G/P/SUM calculation step dividing the digits of the A and B into groups for every m bits and calculating an addition result SUM0, which is given when G, P, a carry input is H, and an addition result SUM1, which is given when the carry input is L, a carry calculation circuit calculating a carry for each group, and a SUM selection step selecting the SUM0 or SUM1 calculated for each group according to the respective carries outputted by the carry calculation circuit. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
