51 lines
1.5 KiB
C
51 lines
1.5 KiB
C
|
/*
|
||
|
|
* This file is a part of Pcompress, a chunked parallel multi-
|
||
|
|
* algorithm lossless compression and decompression program.
|
||
|
|
*
|
||
|
|
* Copyright (C) 2012 Moinak Ghosh. All rights reserved.
|
||
|
|
* Use is subject to license terms.
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU Lesser General Public
|
||
|
|
* License as published by the Free Software Foundation; either
|
||
|
|
* version 3 of the License, or (at your option) any later version.
|
||
|
|
*
|
||
|
|
* This program is distributed in the hope that it will be useful,
|
||
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
|
|
* Lesser General Public License for more details.
|
||
|
|
*
|
||
|
|
* moinakg@belenix.org, http://moinakg.wordpress.com/
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "transpose.h"
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Perform a simple matrix transpose of the given buffer in "from".
|
||
|
|
* If the buffer contains tables of numbers or structured data a
|
||
|
|
* transpose can potentially help improve compression ratio by
|
||
|
|
* bringing repeating values in columns into row ordering.
|
||
|
|
*/
|
||
|
|
void
|
||
|
|
transpose(unsigned char *from, unsigned char *to, uint64_t buflen, uint64_t stride, rowcol_t rc)
|
||
|
|
{
|
||
|
|
uint64_t rows, cols, i, j, k, l;
|
||
|
|
|
||
|
|
if (rc == ROW) {
|
||
|
|
rows = buflen / stride;
|
||
|
|
cols = stride;
|
||
|
|
} else {
|
||
|
|
cols = buflen / stride;
|
||
|
|
rows = stride;
|
||
|
|
}
|
||
|
|
k = 0;
|
||
|
|
for (j = 0; j < rows; j++) {
|
||
|
|
l = 0;
|
||
|
|
for (i = 0; i < cols; i++) {
|
||
|
|
to[j + l] = from[i + k];
|
||
|
|
l += rows;
|
||
|
|
}
|
||
|
|
k += cols;
|
||
|
|
}
|
||
|
|
}
|