Merge pull request #6 from el-supremo/master

My own version of AudioSynthWaveform. Sine is generated with arm_sin_q15...

Audio.cpp

 
 
 
+#ifdef ORIGINAL_AUDIOSYNTHWAVEFORM
 /******************************************************************/
-// PAH - add ramp-up and ramp-down at the beginning and end of the wave
-// 
+// PAH - add ramp-up and ramp-down to the onset of the wave
+// the length is specified in samples
 void AudioSynthWaveform::set_ramp_length(uint16_t r_length)
 {
 	if(r_length < 0) {
 		phase += phase_increment * AUDIO_BLOCK_SAMPLES;
 	}
 }
+#else
+/******************************************************************/
+// PAH - add ramp-up and ramp-down to the onset of the wave
+// the length is specified in samples
+void AudioSynthWaveform::set_ramp_length(uint16_t r_length)
+{
+  if(r_length < 0) {
+    ramp_length = 0;
+    return;
+  }
+  // Don't set the ramp length longer than about 4 milliseconds
+  if(r_length > 44*4) {
+    ramp_length = 44*4;
+    return;
+  }
+  ramp_length = r_length;
+}
+
+boolean AudioSynthWaveform::begin(float t_amp,int t_hi,short type)
+{
+  tone_type = type;
+//  tone_amp = t_amp;
+  amplitude(t_amp);
+  tone_freq = t_hi;
+  if(t_hi < 1)return false;
+  if(t_hi >= AUDIO_SAMPLE_RATE_EXACT/2)return false;
+  tone_phase = 0;
+  tone_incr = (0x100000000LL*t_hi)/AUDIO_SAMPLE_RATE_EXACT;
+  if(0) {
+    Serial.print("AudioSynthWaveform.begin(tone_amp = ");
+    Serial.print(t_amp);
+    Serial.print(", tone_hi = ");
+    Serial.print(t_hi);
+    Serial.print(", tone_incr = ");
+    Serial.print(tone_incr,HEX);
+    //  Serial.print(", tone_hi = ");
+    //  Serial.print(t_hi);
+    Serial.println(")");
+  }
+  return(true);
+}
+
+
+void AudioSynthWaveform::update(void)
+{
+  audio_block_t *block;
+  short *bp;
+  // temporary for ramp in sine
+  uint32_t ramp_mag;
+  // temporaries for TRIANGLE
+  uint32_t mag;
+  short tmp_amp;
+
+  
+  if(tone_freq == 0)return;
+  //          L E F T  C H A N N E L  O N L Y
+  block = allocate();
+  if(block) {
+    bp = block->data;
+    switch(tone_type) {
+    case TONE_TYPE_SINE:
+      for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
+        // The value of ramp_up is always initialized to RAMP_LENGTH and then is
+        // decremented each time through here until it reaches zero.
+        // The value of ramp_up is used to generate a Q15 fraction which varies
+        // from [0 - 1), and multiplies this by the current sample
+        if(ramp_up) {
+          // ramp up to the new magnitude
+          // ramp_mag is the Q15 representation of the fraction
+          // Since ramp_up can't be zero, this cannot generate +1
+          ramp_mag = ((ramp_length-ramp_up)<<15)/ramp_length;
+          ramp_up--;
+          // adjust tone_phase to Q15 format and then adjust the result
+          // of the multiplication
+          *bp = (short)((arm_sin_q15(tone_phase>>17) * tone_amp) >> 15);
+          *bp++ = (*bp * ramp_mag)>>15;
+        } 
+        else if(ramp_down) {
+          // ramp down to zero from the last magnitude
+          // The value of ramp_down is always initialized to RAMP_LENGTH and then is
+          // decremented each time through here until it reaches zero.
+          // The value of ramp_down is used to generate a Q15 fraction which varies
+          // from (1 - 0], and multiplies this by the current sample
+          // avoid RAMP_LENGTH/RAMP_LENGTH because Q15 format
+          // cannot represent +1
+          ramp_mag = ((ramp_down - 1)<<15)/ramp_length;
+          ramp_down--;
+          // adjust tone_phase to Q15 format and then adjust the result
+          // of the multiplication
+          *bp = (short)((arm_sin_q15(tone_phase>>17) * last_tone_amp) >> 15);
+          *bp++ = (*bp * ramp_mag)>>15;
+        } else {
+          // adjust tone_phase to Q15 format and then adjust the result
+          // of the multiplication
+          *bp++ = (short)((arm_sin_q15(tone_phase>>17) * tone_amp) >> 15);
+        } 
+        
+        // phase and incr are both unsigned 32-bit fractions
+        tone_phase += tone_incr;
+      }
+      break;
+      
+    case TONE_TYPE_SQUARE:
+      for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
+        if(tone_phase & 0x80000000)*bp++ = -tone_amp;
+        else *bp++ = tone_amp;
+        // phase and incr are both unsigned 32-bit fractions
+        tone_phase += tone_incr;
+      }
+      break;
+      
+    case TONE_TYPE_SAWTOOTH:
+      for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
+        *bp = ((short)(tone_phase>>16)*tone_amp) >> 15;
+        bp++;
+        // phase and incr are both unsigned 32-bit fractions
+        tone_phase += tone_incr;
+      }
+      break;
+
+    case TONE_TYPE_TRIANGLE:
+      for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
+        if(tone_phase & 0x80000000) {
+          // negative half-cycle
+          tmp_amp = -tone_amp;
+        } 
+        else {
+          // positive half-cycle
+          tmp_amp = tone_amp;
+        }
+        mag = tone_phase << 2;
+        // Determine which quadrant
+        if(tone_phase & 0x40000000) {
+          // negate the magnitude
+          mag = ~mag + 1;
+        }
+        *bp++ = ((short)(mag>>17)*tmp_amp) >> 15;
+        tone_phase += tone_incr;
+      }
+      break;
+    }
+    // send the samples to the left channel
+    transmit(block,0);
+    release(block);
+  }
+}
+
+
+#endif
 
 
 

Audio.h

 
 
 
+#ifdef ORIGINAL_AUDIOSYNTHWAVEFORM
 class AudioSynthWaveform : public AudioStream
 {
 public:
 	uint16_t ramp_length;
 };
 
+#else
+
+#define AUDIO_SAMPLE_RATE_ROUNDED (44118)
+
+#define DELAY_PASSTHRU -1
+
+#define TONE_TYPE_SINE     0
+#define TONE_TYPE_SAWTOOTH 1
+#define TONE_TYPE_SQUARE   2
+#define TONE_TYPE_TRIANGLE 3
+
+class AudioSynthWaveform : 
+public AudioStream
+{
+public:
+  AudioSynthWaveform(void) : 
+  AudioStream(0,NULL), tone_amp(0), ramp_up(0), ramp_down(0), 
+  ramp_length(0), tone_phase(0), tone_incr(0),
+  tone_type(0), tone_freq(0)
+  { 
+  }
+  // Change the frequency on-the-fly to permit a phase-continuous
+  // change between two frequencies.
+  void frequency(int t_hi)
+  {
+    tone_incr = (0x100000000LL*t_hi)/AUDIO_SAMPLE_RATE_EXACT;  
+  }
+  // If ramp_length is non-zero this will set up
+  // either a rmap up or a ramp down when a wave
+  // first starts or when the amplitude is set
+  // back to zero.
+  // Note that if the ramp_length is N, the generated
+  // wave will be N samples longer than when it is not
+  // ramp
+  void amplitude(float n) {        // 0 to 1.0
+    if (n < 0) n = 0;
+    else if (n > 1.0) n = 1.0;
+    // Ramp code
+    if(tone_amp && (n == 0)) {
+      ramp_down = ramp_length;
+      ramp_up = 0;
+      last_tone_amp = tone_amp;
+    }
+    else if((tone_amp == 0) && n) {
+      ramp_up = ramp_length;
+      ramp_down = 0;
+      // reset the phase when the amplitude was zero
+      // and has now been increased. Note that this
+      // happens even if the wave is not ramped
+      // so that the signal starts at zero
+      tone_phase = 0;
+    }
+    // set new magnitude
+    tone_amp = n * 32767.0;
+  }
+  boolean begin(float t_amp,int t_hi,short t_type);
+  virtual void update(void);
+  void set_ramp_length(uint16_t r_length);
+
+private:
+  short    tone_amp;
+  short    last_tone_amp;
+  short    tone_freq;
+  uint32_t tone_phase;
+  uint32_t tone_incr;
+  short    tone_type;
+
+  uint32_t ramp_down;
+  uint32_t ramp_up;
+  uint16_t ramp_length;
+};
+
+#endif