I/O Permutations (2D Case) - 2023.2 English

Vitis Tutorials: AI Engine (XD100)

Document ID
XD100
Release Date
2024-03-05
Version
2023.2 English

The figure below illustrates how to compute the I/O permutations required for a 2D PFA solution. The input permutation relies on a simple modulo computation with the relatively prime factors $N_1$ and $N_2$. The figure gives a specific sample with $N_1=3% and $N_2=5$. The input index mapping may be written in a 2D matrix form, or as a 1D address permutation $P_i$.

The output permutation mapping relies on a similar modulo computation but with factors $K_3$ and $K_4$ computed from $N_1$ and $N_2$ and their “multiplicative modulo inverses”. Such an inverse $(a^{-1})_N\equiv I$ is defined such that $mod(a\times I,N)=1$. Using this to solve for $(N_2^{-1})_{N_1}$ and $(N_1^{-1})_{N_2}$ yields the solution of $K_3=10$ and $K_4=6$ shown in the figure. Once again, the output index mapping may be written in a 2D matrix form, or as a 1D address permutation $P_o$.

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