161 lines
3.7 KiB
C
161 lines
3.7 KiB
C
/*-------------------------------------------------------------------------
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Implementation file for translation table.
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Mark Koennecke, October 1997
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copyright: see copyright.h
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---------------------------------------------------------------------------*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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#include "table.h"
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/*-------------------------------------------------------------------------*/
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typedef struct __SicsTable {
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float *fVal1;
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float *fVal2;
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int iLength;
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} STable;
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/*-------------------------------------------------------------------------*/
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pSTable CreateTable(FILE * fd)
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{
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pSTable pNew = NULL;
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long lStart, lEnd, lData, i;
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char *pBuffer = NULL, *pEnd = NULL, *pEndLine, *pPtr;
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int iLength, iRet;
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float fVal1, fVal2;
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assert(fd);
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/* find length of file, create a buffer and read it in */
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lStart = ftell(fd);
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fseek(fd, 0L, SEEK_END);
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lEnd = ftell(fd);
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lData = lEnd - lStart;
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pBuffer = (char *) malloc(lData * sizeof(char));
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if (!pBuffer) {
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return NULL;
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}
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fseek(fd, lStart, SEEK_SET);
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fread(pBuffer, sizeof(char), lData, fd);
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/* find number of lines */
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for (i = 0, iLength = 0; i < lData; i++) {
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if (pBuffer[i] == '\n') {
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iLength++;
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}
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}
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/* allocate the table structure */
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pNew = (pSTable) malloc(sizeof(STable));
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if (!pNew) {
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free(pBuffer);
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return NULL;
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}
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pNew->iLength = iLength;
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pNew->fVal1 = (float *) malloc(sizeof(float) * iLength);
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pNew->fVal2 = (float *) malloc(sizeof(float) * iLength);
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if ((!pNew->fVal1) || (!pNew->fVal2)) {
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free(pBuffer);
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free(pNew);
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return NULL;
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}
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memset(pNew->fVal1, 0, iLength * sizeof(float));
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memset(pNew->fVal2, 0, iLength * sizeof(float));
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/* dodge through the file reading pairs until end */
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pPtr = pBuffer;
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pEnd = pBuffer + lData;
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pEndLine = pBuffer;
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i = 0;
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while (pEndLine < pEnd) {
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if (*pEndLine == '\n') {
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*pEndLine = '\0';
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iRet = sscanf(pPtr, "%f %f", &fVal1, &fVal2);
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if (iRet == 2) {
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pNew->fVal1[i] = fVal1;
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pNew->fVal2[i] = fVal2;
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i++;
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}
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pEndLine++;
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pPtr = pEndLine;
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} else {
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pEndLine++;
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}
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}
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free(pBuffer);
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return pNew;
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}
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/*--------------------------------------------------------------------------*/
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void DeleteTable(pSTable self)
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{
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if (self->fVal1) {
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free(self->fVal1);
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}
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if (self->fVal2) {
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free(self->fVal2);
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}
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free(self);
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}
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/*--------------------------------------------------------------------------*/
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int InterpolateVal1(pSTable self, float fKey, float *fResult)
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{
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float fFrac;
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int i1, i;
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assert(self);
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assert(self->fVal1);
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assert(self->fVal2);
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/* search the entry point */
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for (i = 0; i < self->iLength; i++) {
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if (self->fVal1[i] >= fKey) {
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i1 = i;
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break;
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}
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}
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if (i1 >= self->iLength) {
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return 0;
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}
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/* interpolate */
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fFrac = (fKey - self->fVal1[i1 - 1])
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/ (self->fVal1[i1] - self->fVal1[i1 - 1]);
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*fResult = self->fVal2[i1 - 1]
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+ fFrac * (self->fVal2[i1] - self->fVal2[i1 - 1]);
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return 1;
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}
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/*---------------------------------------------------------------------------*/
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int InterpolateVal2(pSTable self, float fKey, float *fResult)
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{
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float fFrac;
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int i1, i;
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assert(self);
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assert(self->fVal1);
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assert(self->fVal2);
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/* search the entry point */
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for (i = 0; i < self->iLength; i++) {
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if (self->fVal2[i] <= fKey) {
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i1 = i;
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break;
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}
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}
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if (i1 >= self->iLength) {
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return 0;
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}
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/* interpolate */
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fFrac = (fKey - self->fVal2[i1 - 1])
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/ (self->fVal2[i1] - self->fVal2[i1 - 1]);
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*fResult = self->fVal1[i1 - 1]
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+ fFrac * (self->fVal1[i1] - self->fVal1[i1 - 1]);
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return 1;
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}
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