mealy.c

这是一个c＋＋编写的WCDMA链路采用RAKE接收的方针源代码

/*
 |
 | 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:      Convolutional encoder
 | Author:      C. Britton Rorabaugh
 | Date:        January 12, 1999
 |
 | History:
 |              January 12, 1999 Tommi Makelainen
 |                      Modified Rorabaugh's example code
 |			to rate 1/3 code with constraint length
 |			K=9 (i.e. length of memory shift register).
 |
 */

#include <stdlib.h>
#include <math.h>
#include <ctype.h>
#include <string.h> 
#include <stdio.h>
#include "utility.h"   
#include "mealy.h"
#include "errormsg.h"


/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEncoder_R1o3_Init
 * Desc.:     Initializes Mealy encoder for R=1/3, K=9 convolutional code.
 *
 */
void MealyEncoder_R1o3_Init(
          MealyEncoder* this,  /* IN/OUT: encoder data */
          int num_stages,      /* IN: levels in trellis */
          int gen_poly_1,      /* IN: gen. polynomial 1 */
          int gen_poly_2,      /* IN: gen. polynomial 2 */
          int gen_poly_3       /* IN: gen. polynomial 3 */
 		        )
{
  int shift_register;
  int num_states;
  int current_state, input;
  int output_1, output_2, output_3, output;
  int input_bit;

  num_states = IntPower(2, num_stages-1);
  this->Max_Input = 1;
  this->Max_State = num_states-1;

  for(current_state=0; current_state<num_states; current_state++) {
      for(input=0; input<=1; input++) {
	shift_register = current_state;
	input_bit = input<<(num_stages-1);
	shift_register +=input_bit;
	output_1 = Parity(gen_poly_1 & shift_register);
	output_2 = Parity(gen_poly_2 & shift_register);
	output_3 = Parity(gen_poly_3 & shift_register);
	output = (output_1<<2) + (output_2<<1) + output_3;
	this->Output_Symbol[current_state][input] = output;
	this->Next_State[current_state][input] = shift_register>>1;
	printf("state = %d  input = %d  out = %d  next = %d\n", current_state,
			input, output, this->Next_State[current_state][input]);
      } /* end of input loop  */
  } /* end of current_state loop */

  return;
} /* MealyEncoder_R1o3_Init */

/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEncoder_R1o2_Init
 * Desc.:     Initializes Mealy encoder for R=1/2,K=9 convolutional code.
 *
 */
void MealyEncoder_R1o2_Init(
           MealyEncoder* this, /* IN/OUT: encoder data */
	   int num_stages,     /* IN: convolutional encoder memory length */
	   int gen_poly_1,     /* IN: gen. polynomial 1 */
	   int gen_poly_2)     /* IN: gen. polynomial 2 */
{
  int shift_register;
  int num_states;
  int current_state, input;
  int output_1, output_2, output;
  int input_bit;

  num_states = IntPower(2, num_stages-1);
  this->Max_Input = 1;
  this->Max_State = num_states-1;

  for(current_state=0; current_state<num_states; current_state++) {
      for(input=0; input<=1; input++) {
	shift_register = current_state;
	input_bit = input<<(num_stages-1);
	shift_register +=input_bit;
	output_1 = Parity(gen_poly_1 & shift_register);
	output_2 = Parity(gen_poly_2 & shift_register);
	output = (output_1<<1) + output_2;
	this->Output_Symbol[current_state][input] = output;
	this->Next_State[current_state][input] = shift_register>>1;
	printf("state = %d  input = %d  out = %d  next = %d\n", current_state,
			input, output, this->Next_State[current_state][input]);
      } /* end of input loop  */
  } /* end of current_state loop */
  return;
};


/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEncoder_GetNextState
 * Desc.:     Get the next state in the trellis.
 *
 */
int MealyEncoder_GetNextState(	MealyEncoder* this,
				int current_state,
				int input)
{
  if (input< 0 || input > this->Max_Input) {
     printf("MealyEncoder::GetNextState, bad value for argument 'input'\0");
  }
  if (current_state < 0 || current_state > this->Max_State) {
     printf(
	"MealyEncoder::GetNextState, bad value for argument 'current_state'\0");
  }
  return(this->Next_State[current_state][input]);
}; 


/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEncoder_GetOutput
 * Desc.:     Get the output for the state transition.
 *
 */
int MealyEncoder_GetOutput(
          MealyEncoder* this,    /* IN: encoder status information */
          int current_state,     /* IN: current status in trellis */
          int input)             /* IN: input bit to shift register */
{
  if (input<0 || input >this->Max_Input) {
	printf("in MealyEncoderOutput, bad value for argument 'input'\0");
  }

  if (current_state < 0 || current_state > this->Max_State) {
	printf(
   	"MealyEncoderOutput, bad value for argument 'current_state'\0");
  }
  return(this->Output_Symbol[current_state][input]);
} /* MealyEncoder_GetOutput */


/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEnc_InByte_GetOutput
 * Desc.:     Get the output byte for an input byte.
 *
 */
int MealyEnc_InByte_GetOutput(	MealyEncoder* this,
				int current_state,
				int input[],
				int output[])
{
  int i;
#define BYTE_IN_BITS 8
  for (i=0; i < BYTE_IN_BITS; i++) {
    output[i] = this->Output_Symbol[current_state][ input[i] ];
  }
  return(0);
}; 

/* ------------------------------------------------------------------ */
/*
 * Function:  MealyEncoder_GetTransitionTrigger
 * Desc.:     Get an input that can create transition from
 *            'previous_state' to 'current_state'.
 *
 */
int MealyEncoder_GetTransitionTrigger(
          MealyEncoder* this,     /* IN: encoder status info */
          int previous_state,     /* IN: previous state in trellis */
          int current_state)      /* IN: current state in trellis */
{
  int i;

  if (previous_state < 0 || previous_state > this->Max_State)
    printf(
       "in MealyEncoderOutput, bad value for argument 'previous_state'\0");

  if (current_state < 0 || current_state > this->Max_State)
    printf(
   	"in MealyEncoderOutput, bad value for argument 'current_state'\0");

  for(i=0; i<=1; i++) {
	if(this->Next_State[previous_state][i] == current_state) {
		return(i);
	}
  }           
  printf("Trigger not found for desired transition");
  return(-1);
} /* MealyEncoder_GetTransitionTrigger */


/* ------------------------------------------------------------------ */