Added echo.

README.md

@@ -204,6 +204,7 @@ Here's the full list:
 | `l`    | `vel` | float 0-1+ | Velocity: > 0 to trigger note on, 0 to trigger note off |
 | `L`    | `mod_source` | 0 to OSCS-1 | Which oscillator is used as an modulation/LFO source for this oscillator. Source oscillator will be silent. |
 | `m`    | `portamento` | uint | Time constant (in ms) for pitch changes when note is changed without intervening note-off.  default 0 (immediate), 100 is good. |
+| `M`    | `echo` | float[,int,int,float,float] | Echo parameters -- level, delay_ms, max_delay_ms, feedback, 1st order FIR coefficient. |
 | `N`    | `note` | uint 0-127 | Midi note, sets frequency |
 | `N`    | `latency_ms` | uint | Sets latency in ms. default 0 (see LATENCY) |
 | `o`    | `algorithm` | uint 1-32 | DX7 FM algorithm to use for ALGO type |

amy.py

@@ -148,7 +148,7 @@ def message(osc=0, wave=None, patch=None, note=None, vel=None, amp=None, freq=No
             client=None, retries=None, volume=None, pitch_bend=None, filter_freq = None, resonance = None, bp0=None, bp1=None, eg0_type=None, eg1_type=None,
             debug=None, chained_osc=None, mod_source=None, clone_osc=None, eq=None, filter_type= None, 
             algorithm=None, ratio = None, latency_ms = None, algo_source=None, chorus=None,
-            reverb=None, load_patch=None, store_patch=None, voices=None, external_channel=None, portamento=None):
+            reverb=None, echo=None, load_patch=None, store_patch=None, voices=None, external_channel=None, portamento=None):
 
     m = ""
     if(store_patch is not None): return "u" + str(store_patch)
@@ -186,6 +186,7 @@ def message(osc=0, wave=None, patch=None, note=None, vel=None, amp=None, freq=No
     if(filter_type is not None): m = m + "G" + str(filter_type)
     if(chorus is not None): m = m + 'k%s' % chorus
     if(reverb is not None): m = m + "h%s" % reverb
+    if(echo is not None): m = m + "M%s" % echo
     if(load_patch is not None): m = m + 'K' + str(load_patch)
     if(voices is not None): m = m + 'r' + str(voices)
     if(external_channel is not None): m = m + 'W' + str(external_channel)
@@ -475,3 +476,25 @@ def reverb(level=-1, liveness=-1, damping=-1, xover_hz=-1):
         reverb_xover = str(xover_hz)
     reverb_arg = "%s,%s,%s,%s" % (reverb_level, reverb_liveness, reverb_damping, reverb_xover)
     send(reverb=reverb_arg)
+
+"""
+    Echo control
+"""
+def echo(level=None, delay_ms=None, max_delay_ms=None, feedback=None, filter_coef=None):
+    echo_level = ''
+    echo_delay_ms = ''
+    echo_max_delay_ms = ''
+    echo_feedback = ''
+    echo_filter_coef = ''
+    if level is not None:
+        echo_level = str(level)
+    if delay_ms is not None:
+        echo_delay_ms = str(delay_ms)
+    if max_delay_ms is not None:
+        echo_max_delay_ms = str(max_delay_ms)
+    if feedback is not None:
+        echo_feedback = str(feedback)
+    if filter_coef is not None:
+        echo_filter_coef = str(filter_coef)
+    echo_arg = '%s,%s,%s,%s,%s' % (echo_level, echo_delay_ms, echo_max_delay_ms, echo_feedback, echo_filter_coef)
+    send(echo=echo_arg)

src/AMY-Arduino.cpp

@@ -23,11 +23,11 @@ int32_t AMY::sysclock() {
 }
 
 void AMY::begin() {
-    amy_start(/* cores= */ 1, /* reverb= */ 0, /* chorus= */ 0);
+    amy_start(/* cores= */ 1, /* reverb= */ 0, /* chorus= */ 0, /* echo= */ 0);
 }
 
-void AMY::begin(uint8_t cores, uint8_t reverb, uint8_t chorus) {
-    amy_start(cores, reverb, chorus);
+void AMY::begin(uint8_t cores, uint8_t reverb, uint8_t chorus, uint8_t echo) {
+    amy_start(cores, reverb, chorus, echo);
 }
 
 

src/amy-example-rp2040.c

@@ -146,7 +146,7 @@ int main() {
     sleep_ms(500);
     printf("Clock is set to %d\n", clock_get_hz(clk_sys));
 
-    amy_start(/* cores= */ 2, /* reverb= */ 0, /* chorus= */ 1);
+    amy_start(/* cores= */ 2, /* reverb= */ 0, /* chorus= */ 1, /* echo= */ 1);
 
     gpio_init(CPU0_METER);
     gpio_set_dir(CPU0_METER, GPIO_OUT);

src/amy-example.c

@@ -61,7 +61,7 @@ int main(int argc, char ** argv) {
     example_init_custom();
     #endif
 
-    amy_start(/* cores= */ 1, /* reverb= */ 1, /* chorus= */ 1);
+    amy_start(/* cores= */ 1, /* reverb= */ 1, /* chorus= */ 1, /* echo= */ 1);
 
     ma_encoder_config config = ma_encoder_config_init(ma_encoding_format_wav, ma_format_s16, AMY_NCHANS, AMY_SAMPLE_RATE);
     ma_encoder encoder;

src/amy-message.c

@@ -41,7 +41,7 @@ int main(int argc, char ** argv) {
 
 
 
-    amy_start(/* cores= */ 1, /* reverb= */ 1, /* chorus= */ 1);
+    amy_start(/* cores= */ 1, /* reverb= */ 1, /* chorus= */ 1, /* echo= */1);
     amy_live_start();
     amy_reset_oscs();
 

src/amy.c

@@ -86,7 +86,8 @@ void amy_profiles_print() { for(uint8_t i=0;i<NO_TAG;i++) { AMY_PROFILE_PRINT(i)
 #include "clipping_lookup_table.h"
 #include "delay.h"
 // Final output delay lines.
-delay_line_t **delay_lines; 
+delay_line_t **chorus_delay_lines; 
+delay_line_t **echo_delay_lines; 
 
 #ifdef _POSIX_THREADS
 #include <pthread.h>
@@ -146,12 +147,58 @@ int32_t computed_delta; // can be negative no prob, but usually host is larger #
 uint8_t computed_delta_set; // have we set a delta yet?
 
 
+typedef struct echo_config {
+    SAMPLE level;  // Mix of echo into output.  0 = Echo off.
+    uint32_t delay_samples;  // Current delay, quantized to samples.
+    uint32_t max_delay_samples;  // Maximum delay, i.e. size of allocated delay line.
+    SAMPLE feedback;  // Gain applied when feeding back output to input.
+    SAMPLE filter_coef;  // Echo is filtered by a single real zero, this is its location.  1 = max higpass, -1 = max lowpass.
+} echo_config_t;
+
+echo_config_t echo = {ECHO_DEFAULT_LEVEL, ECHO_DEFAULT_DELAY, ECHO_DEFAULT_MAX_DELAY, ECHO_DEFAULT_FEEDBACK, ECHO_DEFAULT_FILTER_COEF};
+
+SAMPLE *echo_delays[AMY_NCHANS];
+
+uint32_t enclosing_power_of_2(uint32_t n) {
+    uint32_t result = 1;
+    while (result < n)  result <<= 1;
+    return result;
+}
+
+void config_echo(float level, float delay_ms, float max_delay_ms, float feedback, float filter_coef) {
+    uint32_t delay_samples = (uint16_t)(delay_ms / 1000.f * AMY_SAMPLE_RATE);
+    if (level > 0) {
+        if (echo_delay_lines[0] == NULL) {
+            // Delay line len must be power of 2.
+            uint32_t max_delay_samples = enclosing_power_of_2((uint16_t)(max_delay_ms / 1000.f * AMY_SAMPLE_RATE));
+            for (int c = 0; c < AMY_NCHANS; ++c)
+                echo_delay_lines[c] = new_delay_line(max_delay_samples, 0, DELAY_RAM_CAPS);
+            echo.max_delay_samples = max_delay_samples;
+            //fprintf(stderr, "config_echo: max_delay_samples=%d\n", max_delay_samples);
+        }
+        // Apply delay.
+        if (delay_samples > echo.max_delay_samples) delay_samples = echo.max_delay_samples;
+        for (int c = 0; c < AMY_NCHANS; ++c) {
+            echo_delay_lines[c]->fixed_delay = delay_samples;
+        }
+    }
+    echo.level = F2S(level);
+    echo.delay_samples = delay_samples;
+    echo.feedback = F2S(feedback);
+    echo.filter_coef = F2S(filter_coef);
+    //fprintf(stderr, "config_echo: delay_samples=%d level=%.3f feedback=%.3f filter_coef=%.3f\n", delay_samples, level, feedback, filter_coef);
+}
+
+void dealloc_echo_delay_lines(void) {
+    for (uint16_t c = 0; c < AMY_NCHANS; ++c)
+        if (echo_delay_lines[c]) free(echo_delay_lines[c]);
+}
 
 SAMPLE *delay_mod = NULL;
 
 typedef struct chorus_config {
     SAMPLE level;     // How much of the delayed signal to mix in to the output, typ F2S(0.5).
-    int max_delay;   // Max delay when modulating.  Must be <= DELAY_LINE_LEN
+    int max_delay;    // Max delay when modulating.  Must be <= DELAY_LINE_LEN
     float lfo_freq;
     float depth;
 } chorus_config_t;
@@ -161,27 +208,26 @@ chorus_config_t chorus = {CHORUS_DEFAULT_LEVEL, CHORUS_DEFAULT_MAX_DELAY, CHORUS
 
 void alloc_chorus_delay_lines(void) {
     for(uint16_t c=0;c<AMY_NCHANS;++c) {
-        delay_lines[c] = new_delay_line(DELAY_LINE_LEN, DELAY_LINE_LEN / 2, CHORUS_RAM_CAPS);
+        chorus_delay_lines[c] = new_delay_line(DELAY_LINE_LEN, DELAY_LINE_LEN / 2, DELAY_RAM_CAPS);
     }
-    delay_mod = (SAMPLE *)malloc_caps(sizeof(SAMPLE) * AMY_BLOCK_SIZE, CHORUS_RAM_CAPS);
+    delay_mod = (SAMPLE *)malloc_caps(sizeof(SAMPLE) * AMY_BLOCK_SIZE, DELAY_RAM_CAPS);
 }
 
 void dealloc_chorus_delay_lines(void) {
     for(uint16_t c=0;c<AMY_NCHANS;++c) {
-        if (delay_lines[c]) free(delay_lines[c]);
-        delay_lines[c] = NULL;
+        if (chorus_delay_lines[c]) free(chorus_delay_lines[c]);
+        chorus_delay_lines[c] = NULL;
     }
     free(delay_mod);
     delay_mod = NULL;
 }
 
-
 void config_chorus(float level, int max_delay, float lfo_freq, float depth) {
     //fprintf(stderr, "config_chorus: level %.3f max_del %d lfo_freq %.3f depth %.3f\n",
     //        level, max_delay, lfo_freq, depth);
     if (level > 0) {
         // only allocate delay lines if chorus is more than inaudible.
-        if (delay_lines[0] == NULL) {
+        if (chorus_delay_lines[0] == NULL) {
             alloc_chorus_delay_lines();
         }
         // if we're turning on for the first time, start the oscillator.
@@ -197,11 +243,9 @@ void config_chorus(float level, int max_delay, float lfo_freq, float depth) {
             osc_note_on(CHORUS_MOD_SOURCE, freq_of_logfreq(synth[CHORUS_MOD_SOURCE].logfreq_coefs[COEF_CONST]));
         }
         // apply max_delay.
-        for (int core=0; core<AMY_CORES; ++core) {
-            for (int chan=0; chan<AMY_NCHANS; ++chan) {
-                //delay_lines[chan]->max_delay = max_delay;
-                delay_lines[chan]->fixed_delay = (int)max_delay / 2;
-            }
+        for (int chan=0; chan<AMY_NCHANS; ++chan) {
+            //chorus_delay_lines[chan]->max_delay = max_delay;
+            chorus_delay_lines[chan]->fixed_delay = (int)max_delay / 2;
         }
     }
     chorus.max_delay = max_delay;
@@ -264,6 +308,7 @@ int8_t global_init() {
     amy_global.cores = 1;
     amy_global.has_reverb = 1;
     amy_global.has_chorus = 1;
+    amy_global.has_echo = 1;
     return 0;
 }
 
@@ -666,9 +711,10 @@ void amy_reset_oscs() {
     amy_global.eq[1] = F2S(1.0f);
     amy_global.eq[2] = F2S(1.0f);
     reset_parametric();
-    // Reset chorus oscillator
+    // Reset chorus oscillator etc.
     if (AMY_HAS_CHORUS) config_chorus(CHORUS_DEFAULT_LEVEL, CHORUS_DEFAULT_MAX_DELAY, CHORUS_DEFAULT_LFO_FREQ, CHORUS_DEFAULT_MOD_DEPTH);
-    if( AMY_HAS_REVERB) config_reverb(REVERB_DEFAULT_LEVEL, REVERB_DEFAULT_LIVENESS, REVERB_DEFAULT_DAMPING, REVERB_DEFAULT_XOVER_HZ);
+    if (AMY_HAS_REVERB) config_reverb(REVERB_DEFAULT_LEVEL, REVERB_DEFAULT_LIVENESS, REVERB_DEFAULT_DAMPING, REVERB_DEFAULT_XOVER_HZ);
+    if (AMY_HAS_ECHO) config_echo(ECHO_DEFAULT_LEVEL, ECHO_DEFAULT_DELAY, ECHO_DEFAULT_MAX_DELAY, ECHO_DEFAULT_FEEDBACK, ECHO_DEFAULT_FILTER_COEF);
     // Reset patches
     patches_reset();
 }
@@ -727,10 +773,15 @@ int8_t oscs_init() {
         }
     }
     // we only alloc delay lines if the chorus is turned on.
-    if (delay_lines == NULL)
-        delay_lines = (delay_line_t **)malloc(sizeof(delay_line_t *) * AMY_NCHANS);
-    if(AMY_HAS_CHORUS > 0 || AMY_HAS_REVERB > 0) {
-        for (int c = 0; c < AMY_NCHANS; ++c)  delay_lines[c] = NULL;
+    if (chorus_delay_lines == NULL)
+        chorus_delay_lines = (delay_line_t **)malloc(sizeof(delay_line_t *) * AMY_NCHANS);
+    if(AMY_HAS_CHORUS > 0) {
+        for (int c = 0; c < AMY_NCHANS; ++c)  chorus_delay_lines[c] = NULL;
+    }
+    if (echo_delay_lines == NULL)
+        echo_delay_lines = (delay_line_t **)malloc(sizeof(delay_line_t *) * AMY_NCHANS);
+    if(AMY_HAS_ECHO > 0) {
+        for (int c = 0; c < AMY_NCHANS; ++c)  echo_delay_lines[c] = NULL;
     }
     //init_stereo_reverb();
 
@@ -817,6 +868,7 @@ void oscs_deinit() {
         ks_deinit();
     filters_deinit();
     dealloc_chorus_delay_lines();
+    dealloc_echo_delay_lines();
 }
 
 
@@ -1399,19 +1451,27 @@ int16_t * amy_fill_buffer() {
 
         if(AMY_HAS_CHORUS==1) {
             // apply chorus.
-            if(chorus.level > 0 && delay_lines[0] != NULL) {
+            if(chorus.level > 0 && chorus_delay_lines[0] != NULL) {
                 // apply time-varying delays to both chans.
                 // delay_mod_val, the modulated delay amount, is set up before calling render_*.
                 SAMPLE scale = F2S(1.0f);
                 for (int16_t c=0; c < AMY_NCHANS; ++c) {
-                    apply_variable_delay(fbl[0] + c * AMY_BLOCK_SIZE, delay_lines[c],
+                    apply_variable_delay(fbl[0] + c * AMY_BLOCK_SIZE, chorus_delay_lines[c],
                                          delay_mod, scale, chorus.level, 0);
                     // flip delay direction for alternating channels.
                     scale = -scale;
                 }
             }
         }
     }
+    if (AMY_HAS_ECHO == 1) {
+        // Apply echo.
+        if (echo.level > 0 && echo_delay_lines[0] != NULL ) {
+            for (int16_t c=0; c < AMY_NCHANS; ++c) {
+                apply_fixed_delay(fbl[0] + c * AMY_BLOCK_SIZE, echo_delay_lines[c], echo.delay_samples, echo.level, echo.feedback, echo.filter_coef);
+            }
+        }
+    }
     if(AMY_HAS_REVERB) {
         // apply reverb.
         if(reverb.level > 0) {
@@ -1702,22 +1762,30 @@ struct event amy_parse_message(char * message) {
                         /* j, J available */
                         // chorus.level 
                         case 'k': if(AMY_HAS_CHORUS) {
-                            float chorus_params[4] = {AMY_UNSET_VALUE(chorus.depth), AMY_UNSET_VALUE(chorus.depth),
-                                                      AMY_UNSET_VALUE(chorus.depth), AMY_UNSET_VALUE(chorus.depth)};
-                            parse_float_list_message(message + start, chorus_params, 4, AMY_UNSET_VALUE(chorus.depth));
-                            // cpnfig_chorus doesn't understand UNSET, copy existing values.
+                            float chorus_params[4] = {AMY_UNSET_FLOAT, AMY_UNSET_FLOAT, AMY_UNSET_FLOAT, AMY_UNSET_FLOAT};
+                            parse_float_list_message(message + start, chorus_params, 4, AMY_UNSET_FLOAT);
+                            // config_chorus doesn't understand UNSET, copy existing values.
                             if (AMY_IS_UNSET(chorus_params[0])) chorus_params[0] = S2F(chorus.level);
                             if (AMY_IS_UNSET(chorus_params[1])) chorus_params[1] = (float)chorus.max_delay;
                             if (AMY_IS_UNSET(chorus_params[2])) chorus_params[2] = chorus.lfo_freq;
                             if (AMY_IS_UNSET(chorus_params[3])) chorus_params[3] = chorus.depth;
                             config_chorus(chorus_params[0], (int)chorus_params[1], chorus_params[2], chorus_params[3]);
                         }
                         break;
-                        case 'K': e.load_patch = atoi(message+start); break; 
+                        case 'K': e.load_patch = atoi(message+start); break;
                         case 'l': e.velocity=atoff(message + start); break;
                         case 'L': e.mod_source=atoi(message + start); break;
                         case 'm': e.portamento_ms=atoi(message + start); break;
-                        /* M unused */
+                        case 'M': if (AMY_HAS_ECHO) {
+                            float echo_params[5] = {AMY_UNSET_FLOAT, AMY_UNSET_FLOAT, AMY_UNSET_FLOAT, AMY_UNSET_FLOAT, AMY_UNSET_FLOAT};
+                            parse_float_list_message(message + start, echo_params, 5, AMY_UNSET_FLOAT);
+                            if (AMY_IS_UNSET(echo_params[0])) echo_params[0] = S2F(echo.level);
+                            if (AMY_IS_UNSET(echo_params[1])) echo_params[1] = (float)echo.delay_samples * 1000.f / AMY_SAMPLE_RATE;
+                            if (AMY_IS_UNSET(echo_params[2])) echo_params[2] = (float)echo.max_delay_samples * 1000.f / AMY_SAMPLE_RATE;
+                            if (AMY_IS_UNSET(echo_params[3])) echo_params[3] = S2F(echo.feedback);
+                            if (AMY_IS_UNSET(echo_params[4])) echo_params[4] = S2F(echo.filter_coef);
+                            config_echo(echo_params[0], echo_params[1], echo_params[2], echo_params[3], echo_params[4]);
+                        }
                         case 'N': e.latency_ms = atoi(message + start);  break;
                         case 'n': e.midi_note=atoi(message + start); break;
                         case 'o': e.algorithm=atoi(message+start); break;
@@ -1804,7 +1872,7 @@ void amy_stop() {
     oscs_deinit();
 }
 
-void amy_start(uint8_t cores, uint8_t reverb, uint8_t chorus) {
+void amy_start(uint8_t cores, uint8_t reverb, uint8_t chorus, uint8_t echo) {
     #ifdef _POSIX_THREADS
         pthread_mutex_init(&amy_queue_lock, NULL);
     #endif
@@ -1813,6 +1881,7 @@ void amy_start(uint8_t cores, uint8_t reverb, uint8_t chorus) {
     amy_global.cores = cores;
     amy_global.has_chorus = chorus;
     amy_global.has_reverb = reverb;
+    amy_global.has_echo = echo;
     oscs_init();
     //amy_reset_oscs();
 }

src/amy.h

@@ -219,8 +219,10 @@ static inline int isnan_c11(float test)
 }
 
 
+#define AMY_UNSET_FLOAT nanf("")
+
 #define AMY_UNSET_VALUE(var) _Generic((var), \
-    float: nanf(""), \
+    float: AMY_UNSET_FLOAT, \
     uint32_t: UINT32_MAX, \
     uint16_t: UINT16_MAX, \
     int16_t: SHRT_MAX, \
@@ -410,6 +412,7 @@ struct state {
     uint8_t cores;
     uint8_t has_reverb;
     uint8_t has_chorus;
+    uint8_t has_echo;
     float volume;
     float pitch_bend;
     // State of fixed dc-blocking HPF
@@ -454,7 +457,7 @@ uint32_t ms_to_samples(uint32_t ms) ;
 void amy_play_message(char *message);
 struct event amy_parse_message(char * message);
 void amy_restart();
-void amy_start(uint8_t cores, uint8_t reverb, uint8_t chorus);
+void amy_start(uint8_t cores, uint8_t reverb, uint8_t chorus, uint8_t echo);
 void amy_stop();
 void amy_live_start();
 void amy_live_stop();