12bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian/*********************************************************************** 22bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianCopyright (c) 2006-2011, Skype Limited. All rights reserved. 32bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianRedistribution and use in source and binary forms, with or without 42bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianmodification, are permitted provided that the following conditions 52bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianare met: 62bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian- Redistributions of source code must retain the above copyright notice, 72bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianthis list of conditions and the following disclaimer. 82bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian- Redistributions in binary form must reproduce the above copyright 92bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramaniannotice, this list of conditions and the following disclaimer in the 102bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramaniandocumentation and/or other materials provided with the distribution. 112bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian- Neither the name of Internet Society, IETF or IETF Trust, nor the 122bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramaniannames of specific contributors, may be used to endorse or promote 132bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianproducts derived from this software without specific prior written 142bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianpermission. 152bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianTHIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 162bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianAND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 172bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianIMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 182bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 192bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianLIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 202bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianCONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 212bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianSUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 222bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianINTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 232bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianCONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 242bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 252bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh VenkatasubramanianPOSSIBILITY OF SUCH DAMAGE. 262bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian***********************************************************************/ 272bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian 282bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian#ifdef HAVE_CONFIG_H 292bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian#include "config.h" 302bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian#endif 312bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian 322bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian#include "SigProc_FIX.h" 332bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian 342bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian/* Approximation of 2^() (very close inverse of silk_lin2log()) */ 352bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian/* Convert input to a linear scale */ 362bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanianopus_int32 silk_log2lin( 372bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian const opus_int32 inLog_Q7 /* I input on log scale */ 382bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian) 392bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian{ 402bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian opus_int32 out, frac_Q7; 412bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian 422bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian if( inLog_Q7 < 0 ) { 432bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian return 0; 442bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian } else if ( inLog_Q7 >= 3967 ) { 452bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian return silk_int32_MAX; 462bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian } 472bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian 482bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian out = silk_LSHIFT( 1, silk_RSHIFT( inLog_Q7, 7 ) ); 492bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian frac_Q7 = inLog_Q7 & 0x7F; 502bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian if( inLog_Q7 < 2048 ) { 512bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian /* Piece-wise parabolic approximation */ 522bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian out = silk_ADD_RSHIFT32( out, silk_MUL( out, silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ), 7 ); 532bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian } else { 542bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian /* Piece-wise parabolic approximation */ 552bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian out = silk_MLA( out, silk_RSHIFT( out, 7 ), silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ); 562bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian } 572bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian return out; 582bd8b54017b5320bc0c1df9bf86f4cdc9f8db242Vignesh Venkatasubramanian} 59