From 3a320914a54ea0cdb37fa194d5a6fae4e14e4f94 Mon Sep 17 00:00:00 2001
From: Paul Ferrand <paulfd@outlook.fr>
Date: Mon, 9 Dec 2019 19:22:50 +0100
Subject: [PATCH] Added a divide SIMD helper

---
 src/sfizz/Config.h      |  1 +
 src/sfizz/SIMDDummy.cpp |  8 ++++++-
 src/sfizz/SIMDHelpers.h | 50 +++++++++++++++++++++++++++++++++++++++++
 src/sfizz/SIMDSSE.cpp   | 27 +++++++++++++++++++++-
 4 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/src/sfizz/Config.h b/src/sfizz/Config.h
index 346154f8..332b6ea6 100644
--- a/src/sfizz/Config.h
+++ b/src/sfizz/Config.h
@@ -58,6 +58,7 @@ namespace SIMDConfig {
     constexpr bool readInterleaved { true };
     constexpr bool fill { true };
     constexpr bool gain { false };
+    constexpr bool divide { false };
     constexpr bool mathfuns { false };
     constexpr bool loopingSFZIndex { true };
     constexpr bool saturatingSFZIndex { true };
diff --git a/src/sfizz/SIMDDummy.cpp b/src/sfizz/SIMDDummy.cpp
index f1409339..75cbb77f 100644
--- a/src/sfizz/SIMDDummy.cpp
+++ b/src/sfizz/SIMDDummy.cpp
@@ -77,6 +77,12 @@ void sfz::applyGain<float, true>(absl::Span<const float> gain, absl::Span<const
     applyGain<float, false>(gain, input, output);
 }
 
+template <>
+void sfz::divide<float, true>(absl::Span<const float> input, absl::Span<const float> divisor, absl::Span<float> output) noexcept
+{
+    divide<float, false>(input, divisor, output);
+}
+
 template <>
 void sfz::multiplyAdd<float, true>(absl::Span<const float> gain, absl::Span<const float> input, absl::Span<float> output) noexcept
 {
@@ -173,4 +179,4 @@ template <>
 void sfz::diff<float, true>(absl::Span<const float> input, absl::Span<float> output) noexcept
 {
     diff<float, false>(input, output);
-}
\ No newline at end of file
+}
diff --git a/src/sfizz/SIMDHelpers.h b/src/sfizz/SIMDHelpers.h
index 33b8c8ab..bd03ea93 100644
--- a/src/sfizz/SIMDHelpers.h
+++ b/src/sfizz/SIMDHelpers.h
@@ -457,6 +457,56 @@ void applyGain<float, true>(float gain, absl::Span<const float> input, absl::Spa
 template <>
 void applyGain<float, true>(absl::Span<const float> gain, absl::Span<const float> input, absl::Span<float> output) noexcept;
 
+namespace _internals {
+    template <class T>
+    inline void snippetDivSpan(const T*& input, const T*& divisor,T*& output)
+    {
+        *output++ = (*input++) / (*divisor++);
+    }
+}
+
+/**
+ * @brief Divide a vector by another vector
+ *
+ * The output size will be the minimum of the divisor, input span and output span size.
+ *
+ * @tparam T the underlying type
+ * @tparam SIMD use the SIMD version or the scalar version
+ * @param input
+ * @param divisor
+ * @param output
+ */
+template <class T, bool SIMD = SIMDConfig::divide>
+void divide(absl::Span<const T> input, absl::Span<const T> divisor, absl::Span<T> output) noexcept
+{
+    ASSERT(divisor.size() == input.size());
+    ASSERT(input.size() <= output.size());
+    auto* in = input.begin();
+    auto* d = divisor.begin();
+    auto* out = output.begin();
+    auto* sentinel = out + std::min(divisor.size(), std::min(output.size(), input.size()));
+    while (out < sentinel)
+        _internals::snippetDivSpan<T>(in, d, out);
+}
+
+/**
+ * @brief Divide a vector by another in place
+ *
+ * @tparam T the underlying type
+ * @tparam SIMD use the SIMD version or the scalar version
+ * @param output
+ * @param divisor
+ */
+template <class T, bool SIMD = SIMDConfig::divide>
+void divide(absl::Span<T> output,  absl::Span<const T> divisor) noexcept
+{
+    divide<T, SIMD>(output, divisor, output);
+}
+
+template <>
+void divide<float, true>(absl::Span<const float> input, absl::Span<const float> divisor, absl::Span<float> output) noexcept;
+
+
 namespace _internals {
     template <class T>
     inline void snippetMultiplyAdd(const T*& gain, const T*& input, T*& output)
diff --git a/src/sfizz/SIMDSSE.cpp b/src/sfizz/SIMDSSE.cpp
index 253cde36..50b527bb 100644
--- a/src/sfizz/SIMDSSE.cpp
+++ b/src/sfizz/SIMDSSE.cpp
@@ -305,6 +305,31 @@ void sfz::applyGain<float, true>(absl::Span<const float> gain, absl::Span<const
         _internals::snippetGainSpan<float>(g, in, out);
 }
 
+
+template <>
+void sfz::divide<float, true>(absl::Span<const float> input, absl::Span<const float> divisor, absl::Span<float> output) noexcept
+{
+    auto* in = input.begin();
+    auto* out = output.begin();
+    auto* div = divisor.begin();
+    const auto size = std::min(output.size(), std::min(input.size(), divisor.size()));
+    const auto* lastAligned = prevAligned(output.begin() + size);
+
+    while (unaligned(out, in, div) && out < lastAligned)
+        _internals::snippetDivSpan<float>(in, div, out);
+
+    while (out < lastAligned) {
+        _mm_store_ps(out, _mm_div_ps(_mm_load_ps(in), _mm_load_ps(div)));
+        div += TypeAlignment;
+        in += TypeAlignment;
+        out += TypeAlignment;
+    }
+
+    while (out < output.end())
+        _internals::snippetDivSpan<float>(in, div, out);
+}
+
+
 template <>
 void sfz::multiplyAdd<float, true>(absl::Span<const float> gain, absl::Span<const float> input, absl::Span<float> output) noexcept
 {
@@ -809,4 +834,4 @@ void sfz::diff<float, true>(absl::Span<const float> input, absl::Span<float> out
 
     while (in < sentinel)
         _internals::snippetDiff(in, out);
-}
\ No newline at end of file
+}