Barrel shifter for rotating data with or without carry

Claim 2

A barrel shifter comprising: (a) shifting means for selectively shifting an N-bit input data by a given shift count in response to a plurality of shift signals indicative of a shift count in combination and outputting a 2N-bit output data; (b) ANDing means connected to said shifting means for ANDing a carry signal and a first carry rotate signal to insert a a carry bit behind a least significant bit position of the shifted N-bit output in cooperation with the shift signals; and (c) ORing means connected to said shifting means for finding logical sums of each of N lower significant bits and each of N higher significant bits in response to a rotate signal R to obtain an N-bit rotated data without carry, and logical sums of each of N lower significant bits and each of (N-1) higher significant bits in response to a second carry rotate signal CR to obtain an N-bit rotated data with carry.

Claim 3

A barrel shifter for shifting an N-bit data, which comprises: (a) a plurality of parallel-connected selectors each having first series-connected selector elements connected to each bit of the N-bit data for shifting the N-bit data in response to one of shift signals and second series-connected selector elements also connected to each bit of the N-bit data for directly outputting the N-bit data without shift in response to one of inverted shift-signals; (b) a plurality of ANDing means each connected to one of said first series-connected selector elements for inserting a carry bit behind a least significant bit of the shifted N-bit output in response to an AND product of a carry signal and a first carry rotate signal in cooperation with the shift signals; (c) two parallel-connected selectors each having third series-connected selector elements connected to a first plurality of outputs of one of the parallel-connected selectors for outputting (N-1) higher significant bits in response to a second carry rotate signal and fourth series-connected selector elements connected to a second plurality of outputs of the same one of the parallel-connected selectors for outputting N higher significant bits in response to a rotate signal; and (d) ORing means connected to said two parallel-connected selectors for outputting an N-bit rotated data without carry by finding logical sums of each of N lower significant bits and each of N higher significant bits outputted from said fourth series-connected selector elements in response to the rotate signal and for outputting an N-bit rotated data including a carry by finding logical sums of each of N lower significant bits and each of (N-1) higher significant bits outputted from said third series-connected selector elements in response to the second carry rotate signal.

Claim 4

A barrel shifter for shifting an N-bit data, which comprises: (a) a plurality of parallel-connected selectors each having first series-connected selector elements connected to each bit of the N-bit data for shifting the N-bit data in response to one of shift signals and second series-connected selector elements also connected to each bit of the N-bit data for directly outputting the N-bit data without shift in response to one of inverted shift-signals; (b) a plurality of ANDing means each connected to one of said first series-connected selector elements for inserting a carry bit behind a least significant bit of the shifted N-bit output in response to an AND product of a carry signal and a first carry rotate signal in cooperation with the shift signals; (c) two parallel-connected selectors each having third series-connected selector elements connected to a first plurality of outputs of one of the parallel-connected selectors for outputting (N-1) higher significant bits in response to a second carry rotate signal and fourth series-connected selector elements connected to a second plurality of outputs of the same one of the parallel-connected selectors for outputting N higher significant bits in response to a rotate signal; and (d) ORing means connected to said two parallel-connected selectors for outputting an N-bit rotated data without carry by finding logical sums of each of N lower significant bits and each of N higher significant bits outputted from said fourth series-connected selector elements in response to the rotate signal and for outputting an N-bit rotated data including a carry by finding logical sums of each of N lower significant bits and each of (N-1) higher significant bits outputted from said third series-connected selector elements in response to the second carry rotate signal.

Claim 7

The method of claim 3, wherein a relationship between carry-including rotate count Lc and rightward carry-including rotate count Rc is expressed as Lc=N-Rc-1 where N denotes the number of input data bits.

Claim 10

The method of claim 5, wherein a relationship between leftward carry-excluding rotate count L and rightward carry-excluding rotate count R is expressed as L=N-R where N denotes the number of input data bits.