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Diffstat (limited to 'trunk/src/lib/libflac/libflac/bitmath.c')
-rw-r--r-- | trunk/src/lib/libflac/libflac/bitmath.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/trunk/src/lib/libflac/libflac/bitmath.c b/trunk/src/lib/libflac/libflac/bitmath.c new file mode 100644 index 00000000000..d2b54c105e9 --- /dev/null +++ b/trunk/src/lib/libflac/libflac/bitmath.c @@ -0,0 +1,149 @@ +/* libFLAC - Free Lossless Audio Codec library + * Copyright (C) 2001,2002,2003,2004,2005,2006,2007 Josh Coalson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * - Neither the name of the Xiph.org Foundation nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#if HAVE_CONFIG_H +# include <config.h> +#endif + +#include "private/bitmath.h" +#include "flac/assert.h" + +/* An example of what FLAC__bitmath_ilog2() computes: + * + * ilog2( 0) = assertion failure + * ilog2( 1) = 0 + * ilog2( 2) = 1 + * ilog2( 3) = 1 + * ilog2( 4) = 2 + * ilog2( 5) = 2 + * ilog2( 6) = 2 + * ilog2( 7) = 2 + * ilog2( 8) = 3 + * ilog2( 9) = 3 + * ilog2(10) = 3 + * ilog2(11) = 3 + * ilog2(12) = 3 + * ilog2(13) = 3 + * ilog2(14) = 3 + * ilog2(15) = 3 + * ilog2(16) = 4 + * ilog2(17) = 4 + * ilog2(18) = 4 + */ +unsigned FLAC__bitmath_ilog2(FLAC__uint32 v) +{ + unsigned l = 0; + FLAC__ASSERT(v > 0); + while(v >>= 1) + l++; + return l; +} + +unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v) +{ + unsigned l = 0; + FLAC__ASSERT(v > 0); + while(v >>= 1) + l++; + return l; +} + +/* An example of what FLAC__bitmath_silog2() computes: + * + * silog2(-10) = 5 + * silog2(- 9) = 5 + * silog2(- 8) = 4 + * silog2(- 7) = 4 + * silog2(- 6) = 4 + * silog2(- 5) = 4 + * silog2(- 4) = 3 + * silog2(- 3) = 3 + * silog2(- 2) = 2 + * silog2(- 1) = 2 + * silog2( 0) = 0 + * silog2( 1) = 2 + * silog2( 2) = 3 + * silog2( 3) = 3 + * silog2( 4) = 4 + * silog2( 5) = 4 + * silog2( 6) = 4 + * silog2( 7) = 4 + * silog2( 8) = 5 + * silog2( 9) = 5 + * silog2( 10) = 5 + */ +unsigned FLAC__bitmath_silog2(int v) +{ + while(1) { + if(v == 0) { + return 0; + } + else if(v > 0) { + unsigned l = 0; + while(v) { + l++; + v >>= 1; + } + return l+1; + } + else if(v == -1) { + return 2; + } + else { + v++; + v = -v; + } + } +} + +unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v) +{ + while(1) { + if(v == 0) { + return 0; + } + else if(v > 0) { + unsigned l = 0; + while(v) { + l++; + v >>= 1; + } + return l+1; + } + else if(v == -1) { + return 2; + } + else { + v++; + v = -v; + } + } +} |