On-Chip Communication Architectures

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with fewer 1s are mapped to source words with higher probability of occur-

rence), or a value-based mapping code ( vbm—where codewords with fewer 1s are

assigned to lower values, based on the assumption that smaller values are assumed

to have higher probability of occurrence, which is especially true if f

1

is dbm), for

the purpose of activity reduction. Assuming that the probability distribution of the

data is available a priori, the xor–pbm scheme can reduce switching activity on

data buses by 30–40%. The dbm–pbm scheme reduces transition activity by about

5% more than the xor–pbm scheme because dbm skews the input probability dis-

tribution ...