www.pudn.com > AVS_M_ver10.rar > window.c

/* 
*********************************************************************** 
* COPYRIGHT AND WARRANTY INFORMATION 
* 
* Copyright 2007  Audio Video Coding Standard, Part ¢ú 
* 
* This software module was developed by AVS Audio sub-group 
* 
* DISCLAIMER OF WARRANTY 
* 
* These software programs are available to the users without any 
* license fee or royalty on an "as is" basis. The AVS disclaims 
* any and all warranties, whether express, implied, or statutory, 
* including any implied warranties of merchantability or of fitness 
* for a particular purpose. In no event shall the contributors or  
* the AVS be liable for any incidental, punitive, or consequential 
* damages of any kind whatsoever arising from the use of this program. 
* 
* This disclaimer of warranty extends to the user of this program 
* and user's customers, employees, agents, transferees, successors, 
* and assigns. 
* 
* The AVS does not represent or warrant that the program furnished 
* hereunder are free of infringement of any third-party patents. 
* Commercial implementations of AVS, including shareware, may be 
* subject to royalty fees to patent holders. Information regarding 
* the AVS patent policy is available from the AVS Web site at 
* http://www.avs.org.cn 
* 
* THIS IS NOT A GRANT OF PATENT RIGHTS - SEE THE AVS PATENT POLICY. 
************************************************************************ 
*/ 
 
#include  
#define  PI2 6.283185307 
#include "../include/amr_plus.h" 
/*----------------------------------------------------------* 
 * Procedure  cos_window:                                   * 
 *            ~~~~~~~~~~~                                   * 
 *    To find the cos window of length n1+n2                * 
 *                                                          * 
 * fh[i] = cos(-pi/2 ... pi/2)                              * 
 *----------------------------------------------------------*/ 
void cos_window(float *fh, int n1, int n2) 
{ 
  double cc, cte; 
  int i; 
  cte = 0.25*PI2/(float)n1; 
  cc = 0.5*cte - 0.25*PI2; 
  for (i = 0; i < n1; i++) 
  { 
    *fh++ = (float)cos(cc); 
    cc += cte; 
  } 
  cte = 0.25*PI2/(float)n2; 
  cc = 0.5*cte; 
  for (i = 0; i < n2; i++) 
  { 
    *fh++ = (float)cos(cc); 
    cc += cte; 
  } 
  return; 
}