From 259e201fac619ea3d818543fc995ed32eab16df9 Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Mon, 2 Mar 2020 14:07:06 +0100
Subject: [PATCH] Add the multiplyAdd methods for AudioSpan

---
 src/sfizz/AudioSpan.h | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/src/sfizz/AudioSpan.h b/src/sfizz/AudioSpan.h
index b4cb4e75..312c1e1b 100644
--- a/src/sfizz/AudioSpan.h
+++ b/src/sfizz/AudioSpan.h
@@ -11,6 +11,7 @@
 #include "Debug.h"
 #include "LeakDetector.h"
 #include "SIMDHelpers.h"
+#include "absl/types/span.h"
 #include <array>
 #include <initializer_list>
 #include <type_traits>
@@ -306,6 +307,43 @@ public:
         }
     }
 
+    /**
+     * @brief Add another AudioSpan with a compatible number of channels to the current
+     * AudioSpan, applying an elementwise gain to the operand.
+     *
+     * @param other the other AudioSpan
+     * @param gain the gain to apply
+     */
+    template <class U, size_t N, typename = std::enable_if<N <= MaxChannels>>
+    void multiplyAdd(AudioSpan<U, N>& other, absl::Span<const Type> gain)
+    {
+        static_assert(!std::is_const<Type>::value, "Can't allow mutating operations on const AudioSpans");
+        ASSERT(other.getNumChannels() == numChannels);
+        ASSERT(gain.size() == numFrames);
+        if (other.getNumChannels() == numChannels) {
+            for (size_t i = 0; i < numChannels; ++i)
+                sfz::multiplyAdd(gain, other.getConstSpan(i), getSpan(i));
+        }
+    }
+
+    /**
+     * @brief Add another AudioSpan with a compatible number of channels to the current
+     * AudioSpan, applying a fixed gain to the operand.
+     *
+     * @param other the other AudioSpan
+     * @param gain the gain to apply
+     */
+    template <class U, size_t N, typename = std::enable_if<N <= MaxChannels>>
+    void multiplyAdd(AudioSpan<U, N>& other, const Type gain)
+    {
+        static_assert(!std::is_const<Type>::value, "Can't allow mutating operations on const AudioSpans");
+        ASSERT(other.getNumChannels() == numChannels);
+        if (other.getNumChannels() == numChannels) {
+            for (size_t i = 0; i < numChannels; ++i)
+                sfz::multiplyAdd(gain, other.getConstSpan(i), getSpan(i));
+        }
+    }
+
     /**
      * @brief Copy the elements of another AudioSpan with a compatible number of channels
      * to the current AudioSpan.