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dsd2pcm: move the bit reversing code to a generic library

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Instead of doing run-time initialisation, use a constant lookup table.
This commit is contained in:
Max Kellermann
2012-03-21 08:44:43 +01:00
parent 08ce24ec3f
commit c1d0a8b5ce
4 changed files with 73 additions and 8 deletions
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31
src/util/bit_reverse.c Normal file
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/*
* Copyright (C) 2003-2012 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "bit_reverse.h"
/**
* @see http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
*/
const uint8_t bit_reverse_table[256] =
{
#define R2(n) n, n + 2*64, n + 1*64, n + 3*64
#define R4(n) R2(n), R2(n + 2*16), R2(n + 1*16), R2(n + 3*16)
#define R6(n) R4(n), R4(n + 2*4 ), R4(n + 1*4 ), R4(n + 3*4 )
R6(0), R6(2), R6(1), R6(3)
};

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src/util/bit_reverse.h Normal file
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/*
* Copyright (C) 2003-2012 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_BIT_REVERSE_H
#define MPD_BIT_REVERSE_H
#include <glib.h>
#include <stdint.h>
extern const uint8_t bit_reverse_table[256];
G_GNUC_CONST
static inline uint8_t
bit_reverse(uint8_t x)
{
return bit_reverse_table[x];
}
#endif