epics-base/modules/database/src/ioc/db/cvtBpt.c

/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* SPDX-License-Identifier: EPICS
* EPICS Base is distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution.
\*************************************************************************/

/* cvtBpt.c - Convert using breakpoint table
 *
 *      Author:          Marty Kraimer
 *      Date:            04OCT95
 *      This is adaptation of old bldCvtTable
 */

#include "epicsPrint.h"

#include "cvtTable.h"
#include "dbAccess.h"
#include "dbBase.h"
#include "dbStaticLib.h"

static brkTable *findBrkTable(short linr)
{
    dbMenu      *pdbMenu;

    pdbMenu = dbFindMenu(pdbbase,"menuConvert");
    if (!pdbMenu) {
        epicsPrintf("findBrkTable: menuConvert not loaded!\n");
        return NULL;
    }
    if (linr < 0 || linr >= pdbMenu->nChoice) {
        epicsPrintf("findBrkTable: linr=%d but menuConvert only has %d choices\n",
            linr,pdbMenu->nChoice);
        return NULL;
    }
    return dbFindBrkTable(pdbbase,pdbMenu->papChoiceValue[linr]);
}

/* Used by both ao and ai record types */
long cvtRawToEngBpt(double *pval, short linr, short init,
        void **ppbrk, short *plbrk)
{
    double      val = *pval;
    long        status = 0;
    brkTable    *pbrkTable;
    brkInt      *pInt, *nInt;
    short       lbrk;
    int         number;

    if (linr < 2)
        return -1;

    if (init || *ppbrk == NULL) {
        pbrkTable = findBrkTable(linr);
        if (!pbrkTable)
            return S_dbLib_badField;

        *ppbrk = pbrkTable;
        *plbrk = 0;
    } else
        pbrkTable = (brkTable *)*ppbrk;

    number = pbrkTable->number;
    lbrk = *plbrk;

    /* Limit index to the size of the table */
    if (lbrk < 0)
        lbrk = 0;
    else if (lbrk > number-2)
        lbrk = number-2;

    pInt = & pbrkTable->paBrkInt[lbrk];
    nInt = pInt + 1;

    if (nInt->raw > pInt->raw) {
        /* raw values increase down the table */
        while (val > nInt->raw) {
            lbrk++;
            pInt = nInt++;
            if (lbrk > number-2) {
                status = 1;
                break;
            }
        }
        while (val < pInt->raw) {
            if (lbrk <= 0) {
                status = 1;
                break;
            }
            lbrk--;
            nInt = pInt--;
        }
    } else {
        /* raw values decrease down the table */
        while (val <= nInt->raw) {
            lbrk++;
            pInt = nInt++;
            if (lbrk > number-2) {
                status = 1;
                break;
            }
        }
        while(val > pInt->raw) {
            if (lbrk <= 0) {
                status = 1;
                break;
            }
            lbrk--;
            nInt = pInt--;
        }
    }

    *plbrk = lbrk;
    *pval = pInt->eng + (val - pInt->raw) * pInt->slope;

    return status;
}

/* Used by the ao record type */
long cvtEngToRawBpt(double *pval, short linr, short init,
        void **ppbrk, short *plbrk)
{
    double      val = *pval;
    long        status = 0;
    brkTable    *pbrkTable;
    brkInt      *pInt, *nInt;
    short       lbrk;
    int         number;

    if (linr < 2)
        return -1;

    if (init || *ppbrk == NULL) { /*must find breakpoint table*/
        pbrkTable = findBrkTable(linr);
        if (!pbrkTable)
            return S_dbLib_badField;

        *ppbrk = pbrkTable;
        /* start at the beginning */
        *plbrk = 0;
    } else
        pbrkTable = (brkTable *)*ppbrk;

    number = pbrkTable->number;
    lbrk = *plbrk;

    /* Limit index to the size of the table */
    if (lbrk < 0)
        lbrk = 0;
    else if (lbrk > number-2)
        lbrk = number-2;

    pInt = & pbrkTable->paBrkInt[lbrk];
    nInt = pInt + 1;

    if (nInt->eng > pInt->eng) {
        /* eng values increase down the table */
        while (val > nInt->eng) {
            lbrk++;
            pInt = nInt++;
            if (lbrk > number-2) {
                status = 1;
                break;
            }
        }
        while (val < pInt->eng) {
            if (lbrk <= 0) {
                status = 1;
                break;
            }
            lbrk--;
            nInt = pInt--;
        }
    } else {
        /* eng values decrease down the table */
        while (val <= nInt->eng) {
            lbrk++;
            pInt = nInt++;
            if (lbrk > number-2) {
                status = 1;
                break;
            }
        }
        while (val > pInt->eng) {
            if (lbrk <= 0) {
                status = 1;
                break;
            }
            lbrk--;
            nInt = pInt--;
        }
    }

    *plbrk = lbrk;
    *pval = pInt->raw + (val - pInt->eng) / pInt->slope;

    return status;
}