view src/cs/layer1/gtt_include/ctm/viterbi.h @ 220:0ed36de51973

ABB semaphore protection overhaul The ABB semaphone protection logic that came with TCS211 from TI was broken in several ways: * Some semaphore-protected functions were called from Application_Initialize() context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with NU_INVALID_SUSPEND in this context, but the return value wasn't checked, and NU_Release_Semaphore() would be called unconditionally at the end. The latter call would increment the semaphore count past 1, making the semaphore no longer binary and thus no longer effective for resource protection. The fix is to check the return value from NU_Obtain_Semaphore() and skip the NU_Release_Semaphore() call if the semaphore wasn't properly obtained. * Some SPI hardware manipulation was being done before entering the semaphore- protected critical section. The fix is to reorder the code: first obtain the semaphore, then do everything else. * In the corner case of L1/DSP recovery, l1_abb_power_on() would call some non-semaphore-protected ABB & SPI init functions. The fix is to skip those calls in the case of recovery. * A few additional corner cases existed, all of which are fixed by making ABB semaphore protection 100% consistent for all ABB functions and code paths. There is still one remaining problem of priority inversion: suppose a low- priority task calls an ABB function, and some medium-priority task just happens to preempt right in the middle of that semaphore-protected ABB operation. Then the high-priority SPI task is locked out for a non-deterministic time until that medium-priority task finishes its work and goes back to sleep. This priority inversion problem remains outstanding for now.
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 26 Apr 2021 20:55:25 +0000
parents 4e78acac3d88
children
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/*
*******************************************************************************
*
*      COPYRIGHT (C) 2000 BY ERICSSON EUROLAB DEUTSCHLAND GmbH
*
*      The program(s) may be used and/or copied only with the
*      written permission from Ericsson or in accordance
*      with the terms and conditions stipulated in the agreement or
*      contract under which the program(s) have been supplied.
*
*******************************************************************************
*
*      File             : viterbi.h
*      Purpose          : Header file for viterbi.c
*      Author           : Francisco Javier Gil Gomez
*
*      Revision history
*
*      $Log: $
*
*******************************************************************************
*/

#ifndef viterbi_h
#define viterbi_h "$Id: $"

#include <stdio.h>
#include <math.h>

#include "conv_poly.h"   /* definition of viterbi_t */


/***********************************************************************/
/* viterbi_init()                                                      */
/* **************                                                      */
/* Initialization of the Viterbi decoder.                              */
/*                                                                     */
/* output variables:                                                   */
/* *viterbi_state   initialized state variable of the decoder          */
/*                                                                     */
/***********************************************************************/

void viterbi_init(viterbi_t* viterbi_state);


/***********************************************************************/
/* viterbi_reinit()                                                    */
/* ****************                                                    */
/* Re-Initialization of the Viterbi decoder. This function should be   */
/* used for re-setting a Viterbi decoder that has already been         */
/* initialized. In contrast to viterbi_init(), this reinit function    */
/* does not calculate the values of all members of viterbi_state that  */
/* do not change during the execution of the Viterbi algorithm.        */
/*                                                                     */
/* output variables:                                                   */
/* *viterbi_state   initialized state variable of the decoder          */
/*                                                                     */
/***********************************************************************/

void viterbi_reinit(viterbi_t* viterbi_state);


/***********************************************************************/
/* viterbi_exec()                                                      */
/* **************                                                      */
/* Execution of the Viterbi decoder                                    */
/*                                                                     */
/* input variables:                                                    */
/* inputword            Vector with gross bits                         */
/* length_input         Number of valid gross bits in vector inputword.*/
/*                      length_input must be an integer multiple of    */
/*                      CHC_RATE                                       */
/*                                                                     */
/* output variables:                                                   */
/* out                  Vector with the decoded net bits. The net bits */
/*                      are either 0 or 1.                             */
/* *num_valid_out_bits  Number of valid bits in vector out             */
/*                                                                     */
/* input/output variables:                                             */
/* *viterbi_state       State variable of the decoder                  */
/*                                                                     */
/***********************************************************************/

void viterbi_exec(WORD16*  inputword, WORD16  length_input, 
                  WORD16*  out,       WORD16* num_valid_out_bits,
                  viterbi_t* viterbi_state);

#endif