first commit

.gitignore

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+/chord
+*.o

Makefile

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+CC ?=    cc
+CFLAGS=  -Wfatal-errors -Wall -Wextra $(shell pkgconf --cflags portaudio-2.0)
+LDFLAGS= -s -lm $(shell pkgconf --libs portaudio-2.0)
+OBJS=    main.o audio.o
+
+all: chord
+chord: $(OBJS)
+	$(CC) $^ -o $@ $(CFLAGS) $(LDFLAGS)
+%.o: %.c %.h
+	$(CC) -c $< -o $@ $(CFLAGS)
+%.o: %.c
+	$(CC) -c $< -o $@ $(CFLAGS)
+clean:
+	$(RM) *.o $(OBJS) chord

audio.c

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+#include<ctype.h>
+#include<fcntl.h>
+#include<math.h>
+#include<portaudio.h>
+#include<stdbool.h>
+#include<stdint.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<time.h>
+#include<unistd.h>
+#include"audio.h"
+
+Audio aud_new(size_t samplerate,size_t nsamples,size_t channels)
+{
+	Audio aud=(Audio){0};
+	aud.samplerate=samplerate;
+	aud.nsamples=nsamples;
+	aud.channels=channels;
+	aud.data=malloc(nsamples*sizeof(uint16_t));
+	return aud;
+}
+
+void aud_free(Audio*aud)
+{
+	if(!aud)return;
+	if(aud->data)
+		free(aud->data);
+	aud->data=0;
+	*aud=(Audio){0};
+}

audio.h

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+#pragma once
+
+#include<ctype.h>
+#include<fcntl.h>
+#include<math.h>
+#include<portaudio.h>
+#include<stdbool.h>
+#include<stdint.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<time.h>
+#include<unistd.h>
+
+typedef struct Audio
+{
+	size_t samplerate;
+	size_t nsamples;
+	size_t channels;
+	uint16_t*data;
+} Audio;
+
+Audio aud_new(size_t samplerate,size_t nsamples,size_t channels);
+void aud_free(Audio*aud);

main.c

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+/***************
+ * Generate chords
+ * and play them
+ ***************/
+#include<ctype.h>
+#include<fcntl.h>
+#include<math.h>
+#include<portaudio.h>
+#include<stdbool.h>
+#include<stdint.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<time.h>
+#include<signal.h>
+#include<unistd.h>
+#include"audio.h"
+
+#define USAGE	"chord [CHORDs]\n"\
+				"\tCHORD\t[a-z][#b]?[0-9][m]?\n"
+
+// Audio data manipulation
+#define SEMITONE_CONSTANT 1.0594630943592953 // pow(2,1/12.0)
+#define raisesemitone(freq,nsemitones) ((freq)*pow(SEMITONE_CONSTANT,(nsemitones)))
+
+// Chord generators
+#define makechord(aud,freq,...) do{double _f=nametofreq(freq);int _l[]={__VA_ARGS__};tri(aud,_f,GEN);for(size_t i=0;i<sizeof(_l)/sizeof(int);++i)tri(aud,raisesemitone(_f,_l[i]),ADD);}while(0)
+#define chord makechord
+#define M7(aud,f)                   makechord(aud,f,4,7,11)
+#define f7(aud,f)                   makechord(aud,f,4,7,10)
+#define m7(aud,f)                   makechord(aud,f,3,7,10)
+#define d7(aud,f)                   makechord(aud,f,3,6,10)
+
+enum{GEN,ADD};
+
+double nametofreq(const char*name);
+void avg(Audio*aud,size_t blocksize);
+void cleanup(int sig);
+void rnd(Audio*aud,size_t mode);
+void tri(Audio*aud,double freq,size_t mode);
+void zero(Audio*aud);
+void env(Audio*aud);
+
+static Audio aud=(Audio){0};
+static PaStream*pa=NULL;
+
+/*******
+ * Entry point
+ *******/
+int main(int argc,char**argv)
+{
+	signal(SIGINT,cleanup);
+
+	aud=aud_new(44100,22050,1);
+	if(!aud.data)
+	{
+		fprintf(stderr,"error: could not initialize Audio struct\n");
+		cleanup(0);
+		exit(0);
+	}
+	zero(&aud);
+
+	Pa_Initialize();
+	Pa_OpenDefaultStream(&pa,0,aud.channels,paInt16,aud.samplerate,aud.nsamples,NULL,NULL);
+	Pa_StartStream(pa);
+
+	// Macro to play audio
+#define play()    do{Pa_WriteStream(pa,aud.data,aud.nsamples);usleep((((float)aud.nsamples)/aud.samplerate)*1000000);}while(0)
+
+	// Play pre-designed chord scale
+	if(argc<2)
+	{
+		// Play chord scale
+		chord(&aud,  "a4",4,7,11,14);env(&aud);play();
+		chord(&aud,  "g#4",3,6,9,13);env(&aud);play();
+		chord(&aud,  "f#4",3,7,10,14);env(&aud);play();
+		chord(&aud,  "e4",4,7,10,14);env(&aud);play();
+		chord(&aud,  "d4",4,7,11,14);env(&aud);play();
+		chord(&aud,  "c#4",3,7,10,13);env(&aud);play();
+		chord(&aud,  "b3",3,7,10,14);env(&aud);play();
+		chord(&aud,  "a3",4,7,11,14);env(&aud);play();
+		//Pa_Sleep((((float)aud.nsamples)/aud.samplerate)*8);
+	}
+
+	// Play command-line supplied chord names
+	else
+	{
+		for(size_t i=1;i<(size_t)argc;++i)
+		{
+			// Option
+			if(argv[i][0]=='-')
+			{
+				if(strcmp(argv[i],"--help")==0)
+					printf("%s",USAGE);
+			}
+
+			// Chord specification
+			else
+			{
+				printf("playing '%s'\n",argv[i]);
+				if(argv[i][strlen(argv[i])-1]=='m')
+				{
+					chord(&aud,argv[i],3,7,10,14);env(&aud);play();
+				}
+				else
+				{
+					chord(&aud,argv[i],4,7,11,14);env(&aud);play();
+				}
+			}
+		}
+	}
+
+	cleanup(0);
+}
+
+/*******
+ * Convert note name into frequency
+ *******/
+double nametofreq(const char*name)
+{
+	char letter='a';
+	double a0=27.5;
+	double freq=0.0L;
+	size_t letter_offsets[]={0,2,3,5,7,8,10};
+	size_t octave=0;
+	size_t semi=0;
+	size_t str_pos=1;
+
+	if(!name)return freq;
+
+	if(!name[0])return freq;
+	if(!name[1])return freq;
+
+	letter=name[0];
+	if(name[1]=='#')
+		++semi,str_pos=2;
+	else if(name[1]=='b')
+		--semi,str_pos=2;
+
+	if(!name[str_pos])return freq;
+
+	octave=atoi(name+str_pos);
+	if(letter!='a'&&letter!='b')
+		octave=(octave>0)?(octave-1):0;
+	semi+=letter_offsets[letter-'a']+octave*12;
+
+	freq=raisesemitone(a0,semi);
+	return freq;
+}
+
+/*******
+ * Convolver (low-pass filter)
+ *******/
+void avg(Audio*aud,size_t blocksize)
+{
+	if(!aud->data||!aud->nsamples||!aud->channels||!aud->samplerate||!blocksize)return;
+	for(size_t i=blocksize-1;i<aud->nsamples;++i)
+	{
+		uint16_t sum=0;
+		for(size_t j=0;j<blocksize&&(i+j)<aud->nsamples;++j)
+			sum+=aud->data[i+j];
+		/* for(size_t ch=0;ch<aud->channels;++ch,++i) */
+		aud->data[i]=sum/blocksize;
+	}
+}
+
+/*******
+ * Randomize data
+ *******/
+void rnd(Audio*aud,size_t mode)
+{
+	if(!aud->data||!aud->nsamples||!aud->samplerate||!aud->channels)return;
+
+	for(size_t i=0;i<aud->nsamples;++i)
+	{
+		/* for(size_t ch=0;ch<aud->channels;++ch,++i) */
+		uint16_t sample=rand();
+		if(mode==GEN)
+			aud->data[i]=sample;
+		else if(mode==ADD)
+			aud->data[i]=(aud->data[i]+sample)/2;
+	}
+}
+
+/*******
+ * Triangle waveform generator
+ *******/
+void tri(Audio*aud,double freq,size_t mode)
+{
+	if(!aud->data||!aud->nsamples||!aud->samplerate||!aud->channels)return;
+	for(size_t i=0;i<aud->nsamples;++i)
+	{
+		/* for(size_t ch=0;ch<aud->channels;++ch,++i) */
+		//aud->data[i]=sin(i);
+		uint16_t sample=(i%(int)(aud->samplerate/freq))*7;
+		if(mode==GEN)
+			aud->data[i]=sample;
+		else if(mode==ADD)
+			aud->data[i]=(aud->data[i]+sample)/2;
+	}
+}
+
+/*******
+ * Zero all data
+ *******/
+void zero(Audio*aud)
+{
+	if(!aud->data||!aud->nsamples||!aud->channels)return;
+	memset(aud->data,0,aud->nsamples*sizeof(uint16_t));
+}
+
+void cleanup(int sig)
+{
+	if(sig==SIGINT)
+		puts("exiting due to SIGINT");
+	/* else */
+	/* 	puts("bye"); */
+	Pa_AbortStream(pa);
+	Pa_CloseStream(pa);
+	Pa_Terminate();
+	aud_free(&aud);
+}
+
+void env(Audio*aud)
+{
+	if(!aud)return;
+	if(!aud->data)return;
+	size_t range=aud->nsamples/10;
+	for(size_t i=0;i<range;++i)
+		aud->data[i]*=(float)i/range;
+	for(size_t i=0;i<aud->nsamples/8;++i)
+		aud->data[aud->nsamples-1-i]*=(float)i/range;
+}

z

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+#!/usr/bin/ruby
+# Prototype for converting note names to
+# frequencies
+
+def raise_semitone(freq,nsemitones)
+  semitone_constant=2**(1/12.0) #1.059463
+  freq*semitone_constant**nsemitones
+end
+
+def getfreq(name)
+  a0=27.5
+  semi=0
+  semi_name={'a'=>0,'b'=>2,'c'=>3,'d'=>5,'e'=>7,'f'=>8,'g'=>10}
+  str_pos=1
+
+  if name[1]=='#'
+    semi+=1
+    str_pos=2
+  elsif name[1]=='b'
+    semi-=1
+    str_pos=2
+  end
+
+  oct=name[str_pos..].to_i
+  if name[0]!='a'&&name[0]!='b'
+    oct=(oct>0)?(oct-1):(0)
+  end
+  semi+=semi_name[name[0]]+oct*12
+
+  freq=raise_semitone(a0,semi)
+  freq
+end
+
+def test name,correct
+  freq=getfreq name
+  if freq.to_i==correct
+    s=""
+  else
+    s="\t[FAIL: #{correct}]"
+  end
+  print "'#{name}':\t#{freq.to_i}#{s}\n"
+end
+
+def main
+  test 'a0',27
+  test 'a1',55
+  test 'a2',110
+  test 'a3',220
+  test 'a4',440
+  test 'a#4',466
+  test 'bb4',466
+  test 'a5',880
+  test 'a6',1760
+  test 'c3',130
+  test 'g6',1567
+  test 'e1',41
+  test 'e2',82
+  test 'e3',164
+  test 'e4',329
+  test 'e5',659
+  test 'e6',1318
+  test 'f#4',369
+  test 'd7',2349
+  # test 'a10',99999
+end
+
+main