tchord.cpp

在linux下多媒体开发实例linux下多媒体开发

//  tchord.cpp

// guitar chord database and sound functions

#include <fstream.h>
#include <string.h>
#include <v/vdebug.h>

#include "tchord.h"
#include "tutils.h"

// Constructor. Just calls load routine.
tutChords::tutChords(char *fileName)
{
  UserDebug1(Constructor, "tutChords::tutChords(%s)\n", fileName);
  load(fileName);
}

// Load chord database file. Returns -1 on error.
int tutChords::load(char *fileName)
{
  UserDebug1(Misc, "tutChords::load(%s)\n", fileName);
  fstream fs(fileName, ios::in);
  if (fs.bad()) {
    UserDebug1(BadVals, "tutChords::load(%s) can't open file\n", fileName);
    /*    return -1; */
  }

  // check for "magic number" at top of file
  char tmp[255];
  fs >> tmp;
  if (strcmp(tmp, "#GuitarTutor")) {
    UserDebug1(BadVals, "tutChords::load(%s) not a valid data file\n", fileName);
    return -1;
  }

  strcpy(tutChords::fileName, fileName);
  numChords = 0;
  char longName[255], shortName[255], strings[255], sampleFile[255];
       
  do {
    fs >> longName >> shortName >> strings >> sampleFile;
    if (strlen(sampleFile)) {
      // sanity check on strings field
      if ((strlen(strings) != numStrings) ||
	  (strspn(strings, "X012345678") != numStrings)) {
	UserDebug1(BadVals, "tutChords::load(%s) bad data in file\n",
		   fileName);
	return -1;
      }
      // input file uses underscore to indicate space
      StrSub(longName, '_', ' ');
      StrSub(shortName, '_', ' ');
      strcpy(chord[numChords].longName, longName);
      strcpy(chord[numChords].shortName, shortName);
      strcpy(chord[numChords].strings, strings);
      strcpy(chord[numChords].sampleFile, sampleFile);
      chordList[numChords] = chord[numChords].longName;
      numChords++;
      if (numChords >= maxChords) { // check for array overflow
	UserDebug1(BadVals, "tutChords::load(%s) too many chords in file\n",
		   fileName);
	return -1;
      }
      chordList[numChords] = 0; // clear next entry
    }
  }  while (!fs.eof());

  UserDebug1(Misc, "tutChords::load() read %d chords\n", numChords);
  fs.close();
  if (numChords == 0)
    return -1;
  else
    return 0;
}

// Given chord name, return fingering info. Returns -1 on error.
int tutChords::fingering(char *longName, strings_t &strings)
{
  UserDebug1(Misc, "tutChords::fingering(%s)\n", longName);

  for (int i = 0 ; i < numChords ; i++) {
    if (!strcmp(longName, chord[i].longName)) {
      strings = chord[i].strings;
      return 0;
    }
  }
  UserDebug1(BadVals, "tutChords::fingering(%s) can't find chord\n", longName);
  return -1;
}

// Save chord database to file.
int tutChords::save(char *filename)
{
  UserDebug1(Misc, "tutChords::save(%s)\n", fileName);
  fstream fs(filename, ios::out);
  if (fs.bad()) {
    UserDebug1(BadVals, "tutChords::save(%s) can't open file\n", fileName);
    return -1;
  }
  
  // write "magic number" at top of file
  fs << "#GuitarTutor" << endl;

  for (int i = 0 ; i < numChords ; i++) {
    char longName[255], shortName[255];
    strcpy(longName, chord[i].longName);
    strcpy(shortName, chord[i].shortName);
    // convert spaces to underscore
    StrSub(longName, ' ', '_');
    StrSub(shortName, ' ', '_');
    fs << longName << " " << shortName << " " <<
      chord[i].strings[0] << chord[i].strings[1] <<
      chord[i].strings[2] << chord[i].strings[3] <<
      chord[i].strings[4] << chord[i].strings[5] <<
      " " << chord[i].sampleFile << endl;
  }
  fs.close();
  return 0;
}

// Play a chord. Returns -1 on error.
int tutChords::play(char *chordName)
{
  UserDebug1(Misc, "tutChords::play(%s)\n", chordName);
  char *sampleFile = 0;
  const char *sound = "/dev/dsp"; // sound device

  // find the sample
  for (int i = 0 ; i < numChords ; i++) {
    if (!strcmp(chordName, chord[i].longName)) {
      sampleFile = chord[i].sampleFile;
      break;
    }
  }

  // this chord was not found
  if (sampleFile == 0) {
    UserDebug1(BadVals, "tutChords::play(%s) can't find chord\n", chordName);
    return -1;
  }

  // open sample file for read
  fstream in(sampleFile, ios::in);
  if (in.bad()) {
    UserDebug1(BadVals, "tutChords::play() can't open %s\n", sampleFile);
    return -1;
  }

  // open DSP for write
  fstream out(sound, ios::out);
  if (out.bad()) {
    UserDebug1(BadVals, "tutChords::play() can't open %s\n", sound);
    return -1;
  }

  // read sample file, write to DSP
  unsigned char buf;
  while (!in.eof()) {
    in >> buf;
    out << buf;
  }

  // close files
  out.close();
  in.close();

  return 0;
}

// return array of chord names
void tutChords::chordNames(chordList_t list)
{
  UserDebug(Misc, "tutChords::chordNames()\n");
  int i;
  for (i = 0 ; i < numChords ; i++)
    list[i] = chordList[i];
  list[i] = 0;
}