/* Audio Library for Teensy 3.X * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com * * Development of this audio library was funded by PJRC.COM, LLC by sales of * Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop * open source software by purchasing Teensy or other PJRC products. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice, development funding notice, and this permission * notice shall be included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "synth_waveform.h" #include "arm_math.h" #include "utility/dspinst.h" /******************************************************************/ // PAH 140415 - change sin to use Paul's interpolation which is much // faster than arm's sin function // PAH 140316 - fix calculation of sample (amplitude error) // PAH 140314 - change t_hi from int to float // PAH - add ramp-up and ramp-down to the onset of the wave // the length is specified in samples void AudioSynthWaveform::set_ramp_length(int16_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,float t_hi,short type) { tone_type = type; amplitude(t_amp); tone_freq = t_hi > 0.0; if(t_hi <= 0.0)return false; if(t_hi >= AUDIO_SAMPLE_RATE_EXACT/2)return false; tone_phase = 0; frequency(t_hi); 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); } // PAH - 140313 fixed a problem with ramping void AudioSynthWaveform::update(void) { audio_block_t *block; short *bp; // temporary for ramp in sine uint32_t ramp_mag; int32_t val1, val2, val3; uint32_t index, scale; // 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++) { // Calculate interpolated sin index = tone_phase >> 23; val1 = AudioWaveformSine[index]; val2 = AudioWaveformSine[index+1]; scale = (tone_phase >> 7) & 0xFFFF; val2 *= scale; val1 *= 0xFFFF - scale; val3 = (val1 + val2) >> 16; // 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 // calculate the sample tmp_amp = (short)((val3 * tone_amp) >> 15); *bp++ = (tmp_amp * 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 [0 - 1), 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--; tmp_amp = (short)((val3 * last_tone_amp) >> 15); *bp++ = (tmp_amp * ramp_mag)>>15; } else { *bp++ = (short)((val3 * tone_amp) >> 15); } // phase and incr are both unsigned 32-bit fractions tone_phase += tone_incr; // If tone_phase has overflowed, truncate the top bit if(tone_phase & 0x80000000)tone_phase &= 0x7fffffff; } break; case TONE_TYPE_SQUARE: for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) { if(tone_phase & 0x40000000)*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>>15)*tone_amp) >> 15; // 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 += 2*tone_incr; } break; } // send the samples to the left channel transmit(block,0); release(block); } }