例程：通信系统与 MATLAB (Proakis)

/*============================================================================ * Syntax: [sys, x0, str, ts] = * sviterbi(t,x,u,flag,tran_func,leng,tran_prob,plot_flag,V1,V2,V3,V4); *SVITERBI SIMULINK file for convolution decoding using viterbi algorithm. * This file is designed to be used in a SIMULINK S-Function block. * The function requires the system inputs * code_param = [N, K, M, num_state, num_std_sta]; % prepared by simviter * tran_func = [A, B; C, D]; % prepared by simviter * leng % memory length * tran_prob % transfer probability * % when it is not a three row matrix, take the code as hard decision one. * plot_flag % should plot or not. * % when it is not a positive integer, don't plot. * % when it is a positive integer, keep the plot have the time length * % as required. * This function keeps a number of discrete-time states: * figure number. -Inf: to be opened; 0 not need to plot; positive: handle * figure posit. Current figure position. * trace_num. current trace number. * trace_flag. flag to indicate that computation is not under leng. * stater. variable in keeping the very beinging of state. * trace. a LENG-by-NUM_STD_STA matrix storage the traces. * solut. a LENG-by-NUM_STD_STA matrix storage the possible msg. * expense. a 2-by-NUM_STD_STA matrix storage the expense. * * P.S. The most of comments are written in Matlab file. *============================================================================= * Original designed by Wes Wang, * Jun Wu, The Mathworks, Inc. * Feb-07, 1996 * * Copyright (c) 1996 by The MAthWorks, Inc. * All Rights Reserved * $Revision: 1.1 $ $Date: 1996/04/01 19:06:23 $ *============================================================================= */ #define S_FUNCTION_NAME sviterbi /* M-files sviplot1.m sviplot2.m sviplot3.m and sviplot4.m * are needed if you want plot the figures. */ #ifdef MATLAB_MEX_FILE #include "mex.h" #endif #include <math.h> /* need to include simstruc.h for the definition of the SimStruct and * its associated macro definitions. */ #include "simstruc.h" #define NUM_ARGS 8 /* eight additional input arguments */ #define TRAN_FUNC ssGetArg(S,0) /* the length of output vector */ #define LENG ssGetArg(S,1) /* the memory length */ #define TRAN_PROB ssGetArg(S,2) /* the transfer probability */ #define PLOT_FLAG ssGetArg(S,3) /* the flag of plot */ #define V1 ssGetArg(S,4) #define V2 ssGetArg(S,5) #define V3 ssGetArg(S,6) #define V4 ssGetArg(S,7) #define Prim 2 void de2bi(pde, dim, pow_dim, pbi) int *pde, dim, pow_dim, *pbi; { int i,j, tmp; if( pde[0] < 0 ){ /* the first part is for converting the decimal numbers(from 0 to pow_dim) * to binary. */ for(i=0; i < pow_dim; i++){ tmp = i; for(j=0; j < dim; j++){ pbi[i+j*pow_dim] = tmp % Prim; if(j < dim-1) tmp = (int)(tmp/Prim); } } }else{ /* the second part is for converting the decimal numbers(setting by user) * to binary. */ for(i=0; i < pow_dim; i++){ tmp = pde[i]; for(j=0; j < dim; j++){ pbi[i+j*pow_dim] = tmp % Prim; if(j < dim-1) tmp = (int)(tmp/Prim); } } } } static void bi2de(pbi, pow_dim, dim, pde) int *pbi, pow_dim, dim, *pde; { int i, j, k; for(i=0; i<pow_dim; i++) pde[i] = 0; for (i=0; i < pow_dim; i++){ for (j=0; j < dim; j++){ if (pbi[i+j*pow_dim] != 0){ if(j > 0){ for (k=0; k < j; k++) pbi[i+j*pow_dim] = pbi[i+j*pow_dim]*Prim; } } pde[i] = pde[i] + (int)pbi[i+j*pow_dim]; } } } /* * See also vitshort.c and vitshort.m for the two functions following. */ static void shortdbl(expense, sol, n_std_sta, Rwork, Iwork) double *expense, *sol, *Rwork; int *Iwork, n_std_sta; { int i, j, k, PowPowM, aft_indx, len_indx, len, indx; int *wei_indx, *sub_indx; double max; double *wei_mat_exp, *wei_sum, *sol_tmp; double wei_mat_sol; wei_mat_exp = Rwork; wei_sum = Rwork + n_std_sta; sol_tmp = Rwork + 2*n_std_sta; wei_indx = Iwork; sub_indx = Iwork + n_std_sta; PowPowM = n_std_sta * n_std_sta; for(i=0; i < PowPowM; i++) sol_tmp[i] = sol[i]; for(i=1; i <= n_std_sta; i++){ aft_indx = i * n_std_sta - n_std_sta; for(j=1; j <= n_std_sta; j++){ for(k=0; k < n_std_sta; k++) wei_mat_exp[k] = expense[k * n_std_sta + j - 1]; len_indx = 0; for(k=0; k < n_std_sta; k++){ wei_mat_sol = sol_tmp[aft_indx + k]; if ( wei_mat_exp[k] > 0 || wei_mat_sol > 0 ) { wei_sum[k] = 1; }else{ wei_sum[k] = wei_mat_exp[k] + wei_mat_sol; wei_indx[len_indx] = k; len_indx++; } } if (len_indx > 0) { len = 0; max = wei_sum[wei_indx[0]]; sub_indx[0] = wei_indx[0]; k = 1; while (k < len_indx) { if ( max < wei_sum[wei_indx[k]] ) { max = wei_sum[wei_indx[k]]; sub_indx[0] = wei_indx[k]; } k++; } for(k=0; k < len_indx; k++){ if (wei_sum[wei_indx[k]] == max ){ sub_indx[len] = wei_indx[k]; len++; } } indx = sub_indx[0]; if (len > 1){ max = wei_mat_exp[sub_indx[0]]; k = 1; while(k < len){ if( max < wei_mat_exp[sub_indx[k]] ) { max = wei_mat_exp[sub_indx[k]]; indx = sub_indx[k]; } k++; } } sol[aft_indx + j - 1] = wei_sum[indx]; }else{ sol[aft_indx + j - 1] = 1; } } } } static void shortint(expense, sol, n_std_sta, Iwork) int *expense, *sol, *Iwork; int n_std_sta; { int i, j, k, PowPowM, aft_indx, len_indx, len, indx; int min; int wei_mat_sol; int *wei_mat_exp, *wei_sum, *sol_tmp, *wei_indx, *sub_indx; wei_mat_exp = Iwork; wei_sum = Iwork + n_std_sta; wei_indx = Iwork + 2*n_std_sta; sub_indx = Iwork + 3*n_std_sta; sol_tmp = Iwork + 4*n_std_sta; PowPowM = n_std_sta * n_std_sta; for(i=0; i < PowPowM; i++) sol_tmp[i] = sol[i]; for(i=1; i <= n_std_sta; i++){ aft_indx = i * n_std_sta - n_std_sta; for(j=1; j <= n_std_sta; j++){ for(k=0; k < n_std_sta; k++) wei_mat_exp[k] =expense[k * n_std_sta + j - 1]; len_indx = 0; for(k=0; k < n_std_sta; k++){ wei_mat_sol = sol_tmp[aft_indx + k]; if ( wei_mat_exp[k] < 0 || wei_mat_sol < 0 ) { wei_sum[k] = -1; }else{ wei_sum[k] = wei_mat_exp[k] + wei_mat_sol; wei_indx[len_indx] = k; len_indx++; } } if (len_indx > 0) { len = 0; min = wei_sum[wei_indx[0]]; sub_indx[0] = wei_indx[0]; k = 1; while (k < len_indx) { if ( min > wei_sum[wei_indx[k]] ) { min = wei_sum[wei_indx[k]]; sub_indx[0] = wei_indx[k]; } k++; } for(k=0; k < len_indx; k++){ if (wei_sum[wei_indx[k]] == min ){ sub_indx[len] = wei_indx[k]; len++; } } indx = sub_indx[0]; if (len > 1){ min = wei_mat_exp[sub_indx