Fixed to ADSR Analog Mode

ADSR analog mode had two bugs

1. It misused _mm_and_ps so was incorrectly rounding decay time
2. It didn't allow for swells in sustain once the sustain stage
   was underway

This fixes both those problems. In some cases the fix to surge-synthesizer#1 will
change the sound of patches by making the decay time slower (but
more correct).

Closes surge-synthesizer#1439
Closes surge-synthesizer#825

scripts/patch-tool/patch-grep.py

@@ -28,6 +28,22 @@ def sceneFun(xml):
         return False
 
 
+def hasAnalogEnv(xml):
+    try:
+        pt = xml.getElementsByTagName("patch")[0]
+        aem = 0
+        aem = aem + int(pt.getElementsByTagName("a_env1_mode")[0].attributes["value"].nodeValue)
+        aem = aem + int(pt.getElementsByTagName("a_env2_mode")[0].attributes["value"].nodeValue)
+        aem = aem + int(pt.getElementsByTagName("b_env1_mode")[0].attributes["value"].nodeValue)
+        aem = aem + int(pt.getElementsByTagName("b_env2_mode")[0].attributes["value"].nodeValue)
+
+        if aem > 0:
+            return True
+        return False
+    except:
+        return False
+
+
 def containsFX(xml):
     try:
         pt = xml.getElementsByTagName("patch")[0]
@@ -46,7 +62,7 @@ def containsFX(xml):
 
 
 def target(xml):
-    return containsFX(xml)
+    return hasAnalogEnv(xml)
 
 
 def patchToDom(patch):

src/common/dsp/AdsrEnvelope.h

@@ -163,8 +163,13 @@ class AdsrEnvelope : public ModulationSource
 
          bool gate = (envstate == s_attack) || (envstate == s_decay);
          __m128 v_gate = gate ? _mm_set_ss(v_cc) : _mm_set_ss(0.f);
+         __m128 v_is_gate = _mm_cmpgt_ss( v_gate, _mm_set_ss( 0.0 ) );
 
-         discharge = _mm_and_ps(_mm_or_ps(_mm_cmpgt_ss(v_c1_delayed, one), discharge), v_gate);
+         // The original code here was
+         // _mm_and_ps(_mm_or_ps(_mm_cmpgt_ss(v_c1_delayed, one), discharge), v_gate);
+         // which ored in the v_gate value as opposed to the boolean
+         discharge = _mm_and_ps( _mm_or_ps(_mm_cmpgt_ss(v_c1_delayed, one), discharge), v_is_gate );
+
          v_c1_delayed = v_c1;
 
          __m128 S = _mm_load_ss(&lc[s].f);
@@ -174,7 +179,14 @@ class AdsrEnvelope : public ModulationSource
          __m128 v_release = v_gate;
 
          __m128 diff_v_a = _mm_max_ss(_mm_setzero_ps(), _mm_sub_ss(v_attack, v_c1));
-         __m128 diff_v_d = _mm_min_ss(_mm_setzero_ps(), _mm_sub_ss(v_decay, v_c1));
+
+         // This change from a straight min allows sustain swells
+         __m128 diff_vd_kernel = _mm_sub_ss(v_decay, v_c1);
+         __m128 diff_vd_kernel_min = _mm_min_ss(_mm_setzero_ps(), diff_vd_kernel );
+         __m128 dis_and_gate = _mm_and_ps(discharge, v_is_gate );
+         __m128 diff_v_d = _mm_or_ps(_mm_and_ps(dis_and_gate, diff_vd_kernel),
+                                     _mm_andnot_ps(dis_and_gate, diff_vd_kernel_min));
+
          __m128 diff_v_r = _mm_min_ss(_mm_setzero_ps(), _mm_sub_ss(v_release, v_c1));
 
          // calculate coefficients for envelope