/* | | Copyright disclaimer: |   This software was developed at the National Institute of Standards |   and Technology by employees of the Federal Government in the course |   of their official duties. Pursuant to title 17 Section 105 of the |   United States Code this software is not subject to copyright |   protection and is in the public domain. | |   We would appreciate acknowledgement if the software is used. |*//* | Project:	WCDMA simulation environment | Module:      Spreading and despreading  | Author:      Tommi Makelainen, Nokia/NIST | Date:        January 5, 1999 | | History: |              January 5, 1999 Tommi Makelainen |                      Initial version. |		January 7, 1999 Tommi Makelainen |			Spreading code can be longer than one input symbol. |			Now it can be any multiple of data |			symbols times spreading factor. | |		January 9, 1999 Tommi Makelainen |			Data types changed from char to int. | |		April 6, 1999 Tommi Makelainen |                      Added soft despreader function. */#include <stdio.h>#include <math.h>#include "config_wcdma.h"/* * Function:	wcdma_spread * Desc.:	Spreads each data bit from vector 'data' by code *              in vector 'code'. The code has length 'code_len'. * * Note:	 *		Both input data and spreading code are expected *		to given in antipodal (-1,1) presentation. *		The length of data, 'data_len', must be *		multiple of the code length 'code_len'. */int wcdma_spread(	   int data[],		/* IN: input data bit vector */           int data_len,	/* IN: length of input data vector */           int code[],		/* IN: spreading code vector */           int code_len,	/* IN: length of spreading code */           int sf,		/* IN: Chip/data rate, i.e. spreading factor */           int out[])		/* OUT: spreaded output symbol vector */{     int i, out_index, j, k;    int data_symbols_per_code_seq;    data_symbols_per_code_seq = code_len / sf;#ifndef I_KNOW_WHAT_I_DO    if (data_symbols_per_code_seq == 0) {        if ( ((sf / code_len) != 0) && ((data_len / code_len) != 0) ) {            printf("spread: Data length must be multiple of code length divided by spreading factor.\n");            return(-1);        }    } else     if ( ( data_len % data_symbols_per_code_seq ) != 0 ) {      printf("spread: Data length must be multiple of code length divided by spreading factor.\n");      return(-1);    }#endif /* I_KNOW_WHAT_I_DO */    out_index = i = 0;    while (i < data_len) {        for (j=0; j < data_symbols_per_code_seq; j++) {          for (k=j*sf; k < sf; k++) {            out[out_index++] = data[i] * code[k];          }          i++;        } /* for */    } /* while */    return(0);} /* wcdma_spread *//* * Function:	wcdma_hard_despread * Desc.:	Despreads data symbols from vector 'in_data' by code *              in vector 'code'. The code has length 'sf'. * * Note:	 *		Both input data and spreading code are expected *		to given in antipodal (-1,1) presentation. */int wcdma_hard_despread(	     int in_data[],	/* IN: input data symbol vector */             int in_len,	/* IN: length of input data vector */             int code[],	/* IN: spreading code vector */             int code_len,	/* IN: length of spreading code */             int sf,		/* IN: Chip/data rate, i.e. spreading factor */             int out_data[])	/* OUT: despreaded output symbol vector */{     int i, data_length, out_index, j, new_out_index, k;    int antipodal_data, outer_loop_count;    int temp_data = 0;    int data_symbols_per_code_seq;    data_symbols_per_code_seq = code_len / sf;#ifndef I_KNOW_WHAT_I_DO    if ( (in_len % data_symbols_per_code_seq ) != 0) {      printf("despread: Data length must be multiple of ratio between code length and spreading factor.\n");      return(-1);    }#endif /* I_KNOW_WHAT_I_DO */    out_index = i = 0;    outer_loop_count = in_len / sf;    while (out_index < outer_loop_count)     {        for (j=0; j < data_symbols_per_code_seq; j++) {          temp_data = 0;          for (k=j*sf; k < sf; k++, i++) {            temp_data += in_data[i] * code[k];          }          out_data[out_index] = (temp_data > 0) ? 1 : -1;          out_index++;        } /* for */    } /* while */    return(0);} /* wcdma_hard_despread *//* * Function:	wcdma_soft_despread * Desc.:	Despreads data symbols from vector 'in_data' by code *              in vector 'code'. The code has length 'sf'. *		Output soft decision is normalized with  'code_len'. * * Note:	 *		Both input data and spreading code are expected *		to given in antipodal (-1,1) presentation. */int wcdma_soft_despread(	     double in_data[],	/* IN: input data symbol vector */             int in_len,	/* IN: length of input data vector */             int code[],	/* IN: spreading code vector */             int code_len,	/* IN: length of spreading code */             int sf,		/* IN: Chip/data rate, i.e. spreading factor */             double out_data[],	/* OUT: despreaded output symbol vector */             int add_index,     /* IN: index to add next output */             int ringBufLen)    /* IN: ringbuffer length */{     int i, data_length, out_index, j, new_out_index, k;    int antipodal_data, outer_loop_count;    double temp_data = 0;    int data_symbols_per_code_seq;    data_symbols_per_code_seq = code_len / sf;#ifndef I_KNOW_WHAT_I_DO    if ( (in_len % data_symbols_per_code_seq ) != 0) {      printf("despread: Data length must be multiple of ratio between code length and spreading factor.\n");      return(-1);    }#endif /* I_KNOW_WHAT_I_DO */    out_index = i = 0;    outer_loop_count = in_len / sf;    while (out_index < outer_loop_count)     {        for (j=0; j < data_symbols_per_code_seq; j++) {          temp_data = 0;          for (k=j*sf; k < code_len; k++, i++) {            temp_data += in_data[i] * code[k];          }          out_data[add_index] = temp_data / code_len;          add_index = (add_index + 1) % ringBufLen;        } /* for */        out_index++;    } /* while */    return(0);} /* wcdma_soft_despread */