prepro.c

高通的cmda语音压缩算法is96a源代码. 针对自己的dsp将最耗时的c改成汇编就几乎是商用代码了.

/**********************************************************************/
/* QCELP Variable Rate Speech Codec - Simulation of TIA IS96-A, service */
/*     option one for TIA IS95, North American Wideband CDMA Digital  */
/*     Cellular Telephony.                                            */
/*                                                                    */
/* (C) Copyright 1993, QUALCOMM Incorporated                          */
/* QUALCOMM Incorporated                                              */
/* 10555 Sorrento Valley Road                                         */
/* San Diego, CA 92121                                                */
/*                                                                    */
/* Note:  Reproduction and use of this software for the design and    */
/*     development of North American Wideband CDMA Digital            */
/*     Cellular Telephony Standards is authorized by                  */
/*     QUALCOMM Incorporated.  QUALCOMM Incorporated does not         */
/*     authorize the use of this software for any other purpose.      */
/*                                                                    */
/*     The availability of this software does not provide any license */
/*     by implication, estoppel, or otherwise under any patent rights */
/*     of QUALCOMM Incorporated or others covering any use of the     */
/*     contents herein.                                               */
/*                                                                    */
/*     Any copies of this software or derivative works must include   */
/*     this and all other proprietary notices.                        */
/**********************************************************************/
/* prepro.c - preprocess the speech */

#include"struct.h"

dc_block(input, mem, length, control)
float *input, *mem;
INTTYPE   length;
struct CONTROL *control;
{
    INTTYPE i;

    for (i=0; i<length; i++) {
	*mem= *mem *255.0/256.0 + input[i]/256.0;
	input[i]-= *mem;
    }

}