//A.42 packing.c        /******************************************************************            iLBC Speech Coder ANSI-C Source Code            packing.c             Copyright (c) 2001,        Global IP Sound AB.        All rights reserved.        ******************************************************************/        #include <math.h>    #include <stdlib.h>    #include <string.h>       #include"iLBC_define.h"    #include"constants.h"    #include"helpfun.h"        /*----------------------------------------------------------------*     *  splitting an integer into first most significant bits and      *  remaining least significant bits     *---------------------------------------------------------------*/        void packsplit(        int *index,                 /* (i) the value to split */        int *firstpart,             /* (o) the value specified by most                                            significant bits */        int *rest,                  /* (o) the value specified by least                                            significant bits */        int bitno_firstpart,    /* (i) number of bits in most                                            significant part */        int bitno_total             /* (i) number of bits in full range                                            of value */    ){        int bitno_rest = bitno_total-bitno_firstpart;                 *firstpart = *index>>(bitno_rest);        *rest = *index-(*firstpart<<(bitno_rest));    }        /*----------------------------------------------------------------*     *  combining a value corresponding to msb's with a value      *  corresponding to lsb's     *---------------------------------------------------------------*/        void packcombine(         int *index,                 /* (i/o) the msb value in the                                            combined value out */        int rest,                   /* (i) the lsb value */        int bitno_rest              /* (i) the number of bits in the                                            lsb part */    ){        *index = *index<<bitno_rest;        *index += rest;    }        /*----------------------------------------------------------------*     *  packing of bits into bitstream, i.e., vector of bytes     *---------------------------------------------------------------*/        void dopack(         unsigned char **bitstream,  /* (i/o) on entrance pointer to place                                            in bitstream to pack new data,                                            on exit pointer to place in                                            bitstream to pack future                                            data */        int index,                  /* (i) the value to pack */        int bitno,                  /* (i) the number of bits that the                                            value will fit within */        int *pos                /* (i/o) write position in the                                            current byte */    ){        int posLeft;                /* Clear the bits before starting in a new byte */                if ((*pos)==0) {            **bitstream=0;        }            while (bitno>0) {                        /* Jump to the next byte if end of this byte is reached*/                        if (*pos==8) {                *pos=0;                (*bitstream)++;                **bitstream=0;            }                     posLeft=8-(*pos);                /* Insert index into the bitstream */                        if (bitno <= posLeft) {                **bitstream |= (unsigned char)(index<<(posLeft-bitno));                *pos+=bitno;                bitno=0;            } else {                **bitstream |= (unsigned char)(index>>(bitno-posLeft));                                *pos=8;                index-=((index>>(bitno-posLeft))<<(bitno-posLeft));                                bitno-=posLeft;            }        }    }        /*----------------------------------------------------------------*     *  unpacking of bits from bitstream, i.e., vector of bytes     *---------------------------------------------------------------*/        void unpack(         unsigned char **bitstream,  /* (i/o) on entrance pointer to                                            place in bitstream to                                            unpack new data from, on                                            exit pointer to place in                                            bitstream to unpack future                                            data from */        int *index,                 /* (o) resulting value */        int bitno,                  /* (i) number of bits used to                                            represent the value */        int *pos                /* (i/o) read position in the                                            current byte */    ){        int BitsLeft;            *index=0;            while (bitno>0) {                        /* move forward in bitstream when the end of the                byte is reached */                        if (*pos==8) {                *pos=0;                (*bitstream)++;            }                BitsLeft=8-(*pos);                     /* Extract bits to index */                        if (BitsLeft>=bitno) {                *index+=((((**bitstream)<<(*pos)) & 0xFF)>>(8-bitno));                                *pos+=bitno;                bitno=0;            } else {                                if ((8-bitno)>0) {                    *index+=((((**bitstream)<<(*pos)) & 0xFF)>>                        (8-bitno));                    *pos=8;                } else {                    *index+=(((int)(((**bitstream)<<(*pos)) & 0xFF))<<                        (bitno-8));                    *pos=8;                }                bitno-=BitsLeft;            }        }    }