Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 1 | /*********************************************************************** |
| 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| 3 | Redistribution and use in source and binary forms, with or without |
| 4 | modification, are permitted provided that the following conditions |
| 5 | are met: |
| 6 | - Redistributions of source code must retain the above copyright notice, |
| 7 | this list of conditions and the following disclaimer. |
| 8 | - Redistributions in binary form must reproduce the above copyright |
| 9 | notice, this list of conditions and the following disclaimer in the |
| 10 | documentation and/or other materials provided with the distribution. |
| 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
| 12 | names of specific contributors, may be used to endorse or promote |
| 13 | products derived from this software without specific prior written |
| 14 | permission. |
| 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” |
| 16 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 17 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 18 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| 19 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 20 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 21 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 22 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 23 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 24 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 25 | POSSIBILITY OF SUCH DAMAGE. |
| 26 | ***********************************************************************/ |
| 27 | |
| 28 | #ifdef HAVE_CONFIG_H |
| 29 | #include "config.h" |
| 30 | #endif |
| 31 | |
| 32 | #include "main_FLP.h" |
| 33 | |
| 34 | /* Apply sine window to signal vector */ |
| 35 | /* Window types: */ |
| 36 | /* 1 -> sine window from 0 to pi/2 */ |
| 37 | /* 2 -> sine window from pi/2 to pi */ |
| 38 | void silk_apply_sine_window_FLP( |
| 39 | silk_float px_win[], /* O Pointer to windowed signal */ |
| 40 | const silk_float px[], /* I Pointer to input signal */ |
| 41 | const opus_int win_type, /* I Selects a window type */ |
| 42 | const opus_int length /* I Window length, multiple of 4 */ |
| 43 | ) |
| 44 | { |
| 45 | opus_int k; |
| 46 | silk_float freq, c, S0, S1; |
| 47 | |
| 48 | silk_assert( win_type == 1 || win_type == 2 ); |
| 49 | |
| 50 | /* Length must be multiple of 4 */ |
| 51 | silk_assert( ( length & 3 ) == 0 ); |
| 52 | |
| 53 | freq = PI / ( length + 1 ); |
| 54 | |
| 55 | /* Approximation of 2 * cos(f) */ |
| 56 | c = 2.0f - freq * freq; |
| 57 | |
| 58 | /* Initialize state */ |
| 59 | if( win_type < 2 ) { |
| 60 | /* Start from 0 */ |
| 61 | S0 = 0.0f; |
| 62 | /* Approximation of sin(f) */ |
| 63 | S1 = freq; |
| 64 | } else { |
| 65 | /* Start from 1 */ |
| 66 | S0 = 1.0f; |
| 67 | /* Approximation of cos(f) */ |
| 68 | S1 = 0.5f * c; |
| 69 | } |
| 70 | |
| 71 | /* Uses the recursive equation: sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f) */ |
| 72 | /* 4 samples at a time */ |
| 73 | for( k = 0; k < length; k += 4 ) { |
| 74 | px_win[ k + 0 ] = px[ k + 0 ] * 0.5f * ( S0 + S1 ); |
| 75 | px_win[ k + 1 ] = px[ k + 1 ] * S1; |
| 76 | S0 = c * S1 - S0; |
| 77 | px_win[ k + 2 ] = px[ k + 2 ] * 0.5f * ( S1 + S0 ); |
| 78 | px_win[ k + 3 ] = px[ k + 3 ] * S0; |
| 79 | S1 = c * S0 - S1; |
| 80 | } |
| 81 | } |