40 lines
2.4 KiB
C
40 lines
2.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/mem/mem.h"
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#include "tool/viz/lib/convolution.h"
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/**
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* Creates padded array of array indices.
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*
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* This can be used to virtualize the memory of a matrix in one
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* dimension, to make it easy to avoid out-of-bounds access.
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*
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* @return value needs free(retval - leftpad)
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*/
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unsigned *convoindex(unsigned leftpad, unsigned n, unsigned rightpad) {
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unsigned i, j, *p;
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if ((p = malloc(sizeof(unsigned) * (leftpad + n + rightpad)))) {
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i = 0;
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for (j = 0; j < leftpad; ++j) p[i++] = 0;
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for (j = 0; j < n; ++j) p[i++] = j;
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for (j = 0; j < rightpad; ++j) p[i++] = n - 1;
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}
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return p;
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}
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