mirror of
https://github.com/thestk/stk
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97 lines
2.3 KiB
C++
97 lines
2.3 KiB
C++
/********************************************/
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/* Table Lookup Class, */
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/* by Gary P. Scavone, 1999 */
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/* */
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/* This class loads a table of floating */
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/* point doubles, which are assumed to be */
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/* in big-endian format. Linear */
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/* interpolation is performed for */
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/* fractional lookup indexes. */
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/********************************************/
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#include "TablLook.h"
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#include <sys/stat.h>
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#include <sys/types.h>
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#ifdef __LITTLE_ENDIAN__
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#include "swapstuf.h"
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#endif
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TablLook :: TablLook(char *fileName)
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{
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extern double SwapDouble(double);
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// Use the system call "stat" to determine the file length
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struct stat filestat;
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if (stat(fileName, &filestat) == -1)
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{ /* Opening file failed */
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fprintf(stderr,"TablLook - Cannot access or find table lookup file: %s !!!\n",fileName);
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exit(0);
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}
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length = (long) filestat.st_size / 8; // length in 8-byte samples
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// Open the file and read samples into data[]
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FILE *fd;
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fd = fopen(fileName,"rb");
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if (!fd) {
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printf("TablLook - Couldn't open or find table lookup file %s !!!\n",fileName);
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exit(0);
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}
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data = (MY_FLOAT *) new MY_FLOAT[length];
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// Read samples into data[]
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long i = 0;
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double temp;
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while (fread(&temp,8,1,fd)) {
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#ifdef __LITTLE_ENDIAN__
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temp = SwapDouble(temp);
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#endif
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data[i++] = (MY_FLOAT) temp;
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}
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fclose(fd);
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lastOutput = 0.0;
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}
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TablLook :: ~TablLook()
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{
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delete [ ] data;
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}
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long TablLook :: getLength()
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{
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return length;
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}
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MY_FLOAT TablLook :: tick(MY_FLOAT index)
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{
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static MY_FLOAT alpha;
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static long temp;
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if (index > length-1) {
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fprintf(stderr,"TablLook: Index (%f) exceeds table length ... sticking at end!\n", index);
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index = length-1;
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}
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if (index < 0.0) {
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fprintf(stderr,"TablLook: Index (%f) is less than zero ... setting to zero\n", index);
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index = 0.0;
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}
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// Index OK (in range 0 to length-1)
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temp = (long) index; // Integer part of index
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alpha = index - (MY_FLOAT) temp; // Fractional part of index
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if (alpha > 0.0) { // Do linear interpolation
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lastOutput = data[temp];
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lastOutput += (alpha*(data[temp+1] - lastOutput));
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}
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else lastOutput = data[temp];
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return lastOutput;
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}
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MY_FLOAT TablLook :: lastOut()
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{
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return lastOutput;
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}
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