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  Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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  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.
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  names of specific 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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  ***********************************************************************/
  
  //#ifdef HAVE_CONFIG_H
  #include "../config.h"
  //#endif
  
  #include "main.h"
  #include "tuning_parameters.h"
  
  /* Control internal sampling rate */
  opus_int silk_control_audio_bandwidth(
      silk_encoder_state          *psEncC,                        /* I/O  Pointer to Silk encoder state               */
      silk_EncControlStruct       *encControl                     /* I    Control structure                           */
  )
  {
      opus_int   fs_kHz;
      opus_int   orig_kHz;
      opus_int32 fs_Hz;
  
      orig_kHz = psEncC->fs_kHz;
      /* Handle a bandwidth-switching reset where we need to be aware what the last sampling rate was. */
      if( orig_kHz == 0 ) {
          orig_kHz = psEncC->sLP.saved_fs_kHz;
      }
      fs_kHz = orig_kHz;
      fs_Hz = silk_SMULBB( fs_kHz, 1000 );
      if( fs_Hz == 0 ) {
          /* Encoder has just been initialized */
          fs_Hz  = silk_min( psEncC->desiredInternal_fs_Hz, psEncC->API_fs_Hz );
          fs_kHz = silk_DIV32_16( fs_Hz, 1000 );
      } else if( fs_Hz > psEncC->API_fs_Hz || fs_Hz > psEncC->maxInternal_fs_Hz || fs_Hz < psEncC->minInternal_fs_Hz ) {
          /* Make sure internal rate is not higher than external rate or maximum allowed, or lower than minimum allowed */
          fs_Hz  = psEncC->API_fs_Hz;
          fs_Hz  = silk_min( fs_Hz, psEncC->maxInternal_fs_Hz );
          fs_Hz  = silk_max( fs_Hz, psEncC->minInternal_fs_Hz );
          fs_kHz = silk_DIV32_16( fs_Hz, 1000 );
      } else {
          /* State machine for the internal sampling rate switching */
          if( psEncC->sLP.transition_frame_no >= TRANSITION_FRAMES ) {
              /* Stop transition phase */
              psEncC->sLP.mode = 0;
          }
          if( psEncC->allow_bandwidth_switch || encControl->opusCanSwitch ) {
              /* Check if we should switch down */
              if( silk_SMULBB( orig_kHz, 1000 ) > psEncC->desiredInternal_fs_Hz )
              {
                  /* Switch down */
                  if( psEncC->sLP.mode == 0 ) {
                      /* New transition */
                      psEncC->sLP.transition_frame_no = TRANSITION_FRAMES;
  
                      /* Reset transition filter state */
                      silk_memset( psEncC->sLP.In_LP_State, 0, sizeof( psEncC->sLP.In_LP_State ) );
                  }
                  if( encControl->opusCanSwitch ) {
                      /* Stop transition phase */
                      psEncC->sLP.mode = 0;
  
                      /* Switch to a lower sample frequency */
                      fs_kHz = orig_kHz == 16 ? 12 : 8;
                  } else {
                     if( psEncC->sLP.transition_frame_no <= 0 ) {
                         encControl->switchReady = 1;
                         /* Make room for redundancy */
                         encControl->maxBits -= encControl->maxBits * 5 / ( encControl->payloadSize_ms + 5 );
                     } else {
                         /* Direction: down (at double speed) */
                         psEncC->sLP.mode = -2;
                     }
                  }
              }
              else
              /* Check if we should switch up */
              if( silk_SMULBB( orig_kHz, 1000 ) < psEncC->desiredInternal_fs_Hz )
              {
                  /* Switch up */
                  if( encControl->opusCanSwitch ) {
                      /* Switch to a higher sample frequency */
                      fs_kHz = orig_kHz == 8 ? 12 : 16;
  
                      /* New transition */
                      psEncC->sLP.transition_frame_no = 0;
  
                      /* Reset transition filter state */
                      silk_memset( psEncC->sLP.In_LP_State, 0, sizeof( psEncC->sLP.In_LP_State ) );
  
                      /* Direction: up */
                      psEncC->sLP.mode = 1;
                  } else {
                     if( psEncC->sLP.mode == 0 ) {
                         encControl->switchReady = 1;
                         /* Make room for redundancy */
                         encControl->maxBits -= encControl->maxBits * 5 / ( encControl->payloadSize_ms + 5 );
                     } else {
                         /* Direction: up */
                         psEncC->sLP.mode = 1;
                     }
                  }
              } else {
                 if (psEncC->sLP.mode<0)
                    psEncC->sLP.mode = 1;
              }
          }
      }
  
      return fs_kHz;
  }
  