units.c

用你的语音Modem实现像电话一样通话的程序

#include "units.h"
#include <stdlib.h>

float* DB::topower = 0;
int* Freq::freqtable = 0;

DB::DB(float infinitygain)
{
	this->infinitygain = infinitygain;
	if(!topower)
	{
		int i;
		float value;

		// db to power table
		topower = new float[(MAXGAIN - INFINITYGAIN) * 10 + 1];
		topower += -INFINITYGAIN * 10;
		for(i = INFINITYGAIN * 10; i <= MAXGAIN * 10; i++)
		{
			topower[i] = pow(2, (float)i / 10 / 6);
			
//printf("%f %f\n", (float)i/10, topower[i]);
		}
		topower[INFINITYGAIN * 10] = 0;   // infinity gain
	}
	db = 0;
}

float DB::fromdb() { return db = topower[(int)(db * 10)]; }
float DB::fromdb(float db) 
{ 
	if(db > MAXGAIN) db = MAXGAIN;
	if(db <= INFINITYGAIN) return 0;
	return db = topower[(int)(db * 10)]; 
}

// set db to the power given using a formula
float DB::todb(float newdb)
{
	if(newdb == 0) 
		db = INFINITYGAIN;
	else 
	{
		db = (float)(log(newdb) * 19.93156857 /* log(2.0) * 6.0 */);
		if(db < INFINITYGAIN) db = INFINITYGAIN;
	}
	return db;
}


Freq::Freq()
{
	if(!freqtable)
	{
  		int i;

		freqtable = new int[TOTALFREQS + 1];
  		double freq = 28;  // starting frequency
  		long scale = 60;   // some number divisable by three

  		freqtable[0] = 0;
  		for(i = 1; i <= TOTALFREQS; i++)
  		{
    		freqtable[i] = (int)freq;
    		freq = freq + freq / scale;
  		}
	}
	freq = 0;
}

Freq::Freq(const Freq& oldfreq)
{
	this->freq = oldfreq.freq;
}

Freq::fromfreq() 
{
	static int i;

  	for(i = 0; i < TOTALFREQS && freqtable[i] < freq; i++)
    	;
  	return(i);
};

Freq::tofreq(int index) { freq = freqtable[index]; }

Freq& Freq::operator++() 
{
	if(freq < TOTALFREQS) freq++;
	return *this;
}
	
Freq& Freq::operator--()
{
	if(freq > 0) freq--;
	return *this;
}
	
Freq::operator>(Freq &newfreq) { return freq > newfreq.freq; }
Freq::operator<(Freq &newfreq) { return freq < newfreq.freq; }
Freq& Freq::operator=(const Freq &newfreq) { freq = newfreq.freq; return *this; }
int Freq::operator=(const int newfreq) { freq = newfreq; return newfreq; }
Freq::operator!=(Freq &newfreq) { return freq != newfreq.freq; }
Freq::operator==(Freq &newfreq) { return freq == newfreq.freq; }
Freq::operator==(int newfreq) { return freq == newfreq; }
		
char* totext(char *text, long samples, int samplerate, int time_format, float frame_rate)
{
	static int hour, minute;
	switch(time_format)
	{
		case 0:
		{
			static float second;

  			hour = samples / samplerate / 3600;
  			minute = samples / samplerate / 60 - (long)hour * 60;
  			second = (float)samples / samplerate - (long)hour * 3600 - (long)minute * 60;
  			sprintf(text, "%d:%d:%.3f", hour, minute, second);
			return text;
		}
		  break;
		
		case 1:
		{
			static int second, frame;

  			hour = samples / samplerate / 3600;
  			minute = samples / samplerate / 60 - (long)hour * 60;
  			second = samples / samplerate - (long)hour * 3600 - (long)minute * 60;
  			frame = (int)(frame_rate * 
  	 			 (float)((float)samples / samplerate - (long)hour * 3600 - (long)minute * 60 - second))
  	 			 ;
  			sprintf(text, "%d:%02d:%02d:%02d", hour, minute, second, frame);
			return text;
		}
			break;
			
		case 2:
  			sprintf(text, "%ld", samples);
			break;
		
		case 3:
  			sprintf(text, "%x", samples);
			break;
	}
}    // give text representation as time

long fromtext(char *text, int samplerate, int time_format, float frame_rate = 30)
{
	long hours, minutes, frames, total_samples, i, j;
	float seconds;
	char string[10];
	
	switch(time_format)
	{
		case 0:
// get hours
			i = 0;
			j = 0;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			hours = atol(string);
// get minutes
			j = 0;
// skip separator
			while((text[i] < 48 || text[i] > 57) && text[i] != 0) i++;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			minutes = atol(string);
			
// get seconds
			j = 0;
// skip separator
			while((text[i] < 48 || text[i] > 57) && text[i] != 0) i++;
			while((text[i] == '.' || (text[i] >=48 && text[i] <= 57)) && j < 10) string[j++] = text[i++];
			string[j] = 0;
			seconds = atof(string);
			
			total_samples = (long)(((float)seconds + minutes*60 + hours*3600) * samplerate);
			return total_samples;
			break;

		case 1:
// get hours
			i = 0;
			j = 0;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			hours = atol(string);
			
// get minutes
			j = 0;
// skip separator
			while((text[i] < 48 || text[i] > 57) && text[i] != 0) i++;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			minutes = atol(string);
			
// get seconds
			j = 0;
// skip separator
			while((text[i] < 48 || text[i] > 57) && text[i] != 0) i++;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			seconds = atof(string);
			
// get frames
			j = 0;
// skip separator
			while((text[i] < 48 || text[i] > 57) && text[i] != 0) i++;
			while(text[i] >=48 && text[i] <= 57 && j < 10) string[j++] = text[i++];
			string[j] = 0;
			frames = atol(string);
			
			total_samples = (long)(((float)frames / frame_rate + seconds + minutes*60 + hours*3600) * samplerate);
			return total_samples;
			break;

		case 2:
			return atol(text);
			break;
		
		case 3:
			sscanf(text, "%x", &total_samples);
			return total_samples;
	}
}







float toframes(long samples, int sample_rate, float framerate) 
{ 
	return (float)samples / sample_rate * framerate; 
}; // give position in frames



long tosamples(float frames, int sample_rate, float framerate) 
{ 
	float result = (frames / framerate * sample_rate);
	
	if(result - (int)result) result += 1;
	return (long)result;
}; // give position in samples