From ff1e0b6e08209ef63176edfa27d4f675e6f49987 Mon Sep 17 00:00:00 2001
From: Vincent Esche <regexident@gmail.com>
Date: Tue, 12 May 2020 15:15:59 +0200
Subject: [PATCH] Removed coercion of `inout` to temporary pointer

---
 .../Surge/Digital Signal Processing/FFT.swift | 96 +++++++++++--------
 1 file changed, 56 insertions(+), 40 deletions(-)

diff --git a/Sources/Surge/Digital Signal Processing/FFT.swift b/Sources/Surge/Digital Signal Processing/FFT.swift
index 7f75ce8..43ea0c3 100644
--- a/Sources/Surge/Digital Signal Processing/FFT.swift	
+++ b/Sources/Surge/Digital Signal Processing/FFT.swift	
@@ -25,57 +25,73 @@ import Accelerate
 public func fft(_ input: [Float]) -> [Float] {
     var real = [Float](input)
     var imaginary = [Float](repeating: 0.0, count: input.count)
-    var splitComplex = DSPSplitComplex(realp: &real, imagp: &imaginary)
 
-    let length = vDSP_Length(floor(log2(Float(input.count))))
-    let radix = FFTRadix(kFFTRadix2)
-    let weights = vDSP_create_fftsetup(length, radix)
-    withUnsafeMutablePointer(to: &splitComplex) { splitComplex in
-        vDSP_fft_zip(weights!, splitComplex, 1, length, FFTDirection(FFT_FORWARD))
-    }
+    return real.withUnsafeMutableBufferPointer { realBuffer in
+        imaginary.withUnsafeMutableBufferPointer { imaginaryBuffer in
+            var splitComplex = DSPSplitComplex(
+                realp: realBuffer.baseAddress!,
+                imagp: imaginaryBuffer.baseAddress!
+            )
 
-    var magnitudes = [Float](repeating: 0.0, count: input.count)
-    withUnsafePointer(to: &splitComplex) { splitComplex in
-        magnitudes.withUnsafeMutableBufferPointer { magnitudes in
-            vDSP_zvmags(splitComplex, 1, magnitudes.baseAddress!, 1, vDSP_Length(input.count))
+            let length = vDSP_Length(floor(log2(Float(input.count))))
+            let radix = FFTRadix(kFFTRadix2)
+            let weights = vDSP_create_fftsetup(length, radix)
+            withUnsafeMutablePointer(to: &splitComplex) { splitComplex in
+                vDSP_fft_zip(weights!, splitComplex, 1, length, FFTDirection(FFT_FORWARD))
+            }
+
+            var magnitudes = [Float](repeating: 0.0, count: input.count)
+            withUnsafePointer(to: &splitComplex) { splitComplex in
+                magnitudes.withUnsafeMutableBufferPointer { magnitudes in
+                    vDSP_zvmags(splitComplex, 1, magnitudes.baseAddress!, 1, vDSP_Length(input.count))
+                }
+            }
+
+            var normalizedMagnitudes = [Float](repeating: 0.0, count: input.count)
+            normalizedMagnitudes.withUnsafeMutableBufferPointer { normalizedMagnitudes in
+                vDSP_vsmul(sqrt(magnitudes), 1, [2.0 / Float(input.count)], normalizedMagnitudes.baseAddress!, 1, vDSP_Length(input.count))
+            }
+
+            vDSP_destroy_fftsetup(weights)
+
+            return normalizedMagnitudes
         }
     }
-
-    var normalizedMagnitudes = [Float](repeating: 0.0, count: input.count)
-    normalizedMagnitudes.withUnsafeMutableBufferPointer { normalizedMagnitudes in
-        vDSP_vsmul(sqrt(magnitudes), 1, [2.0 / Float(input.count)], normalizedMagnitudes.baseAddress!, 1, vDSP_Length(input.count))
-    }
-
-    vDSP_destroy_fftsetup(weights)
-
-    return normalizedMagnitudes
 }
 
 public func fft(_ input: [Double]) -> [Double] {
     var real = [Double](input)
     var imaginary = [Double](repeating: 0.0, count: input.count)
-    var splitComplex = DSPDoubleSplitComplex(realp: &real, imagp: &imaginary)
 
-    let length = vDSP_Length(floor(log2(Float(input.count))))
-    let radix = FFTRadix(kFFTRadix2)
-    let weights = vDSP_create_fftsetupD(length, radix)
-    withUnsafeMutablePointer(to: &splitComplex) { splitComplex in
-        vDSP_fft_zipD(weights!, splitComplex, 1, length, FFTDirection(FFT_FORWARD))
-    }
+    return real.withUnsafeMutableBufferPointer { realBuffer in
+        imaginary.withUnsafeMutableBufferPointer { imaginaryBuffer in
+            var splitComplex = DSPDoubleSplitComplex(
+                realp: realBuffer.baseAddress!,
+                imagp: imaginaryBuffer.baseAddress!
+            )
 
-    var magnitudes = [Double](repeating: 0.0, count: input.count)
-    withUnsafePointer(to: &splitComplex) { splitComplex in
-        magnitudes.withUnsafeMutableBufferPointer { magnitudes in
-            vDSP_zvmagsD(splitComplex, 1, magnitudes.baseAddress!, 1, vDSP_Length(input.count))
+            let length = vDSP_Length(floor(log2(Float(input.count))))
+            let radix = FFTRadix(kFFTRadix2)
+            let weights = vDSP_create_fftsetupD(length, radix)
+            withUnsafeMutablePointer(to: &splitComplex) { splitComplex in
+                vDSP_fft_zipD(weights!, splitComplex, 1, length, FFTDirection(FFT_FORWARD))
+            }
+
+            var magnitudes = [Double](repeating: 0.0, count: input.count)
+            withUnsafePointer(to: &splitComplex) { splitComplex in
+                magnitudes.withUnsafeMutableBufferPointer { magnitudes in
+                    vDSP_zvmagsD(splitComplex, 1, magnitudes.baseAddress!, 1, vDSP_Length(input.count))
+                }
+            }
+
+            var normalizedMagnitudes = [Double](repeating: 0.0, count: input.count)
+            normalizedMagnitudes.withUnsafeMutableBufferPointer { normalizedMagnitudes in
+                vDSP_vsmulD(sqrt(magnitudes), 1, [2.0 / Double(input.count)], normalizedMagnitudes.baseAddress!, 1, vDSP_Length(input.count))
+            }
+
+            vDSP_destroy_fftsetupD(weights)
+
+            return normalizedMagnitudes
         }
     }
-
-    var normalizedMagnitudes = [Double](repeating: 0.0, count: input.count)
-    normalizedMagnitudes.withUnsafeMutableBufferPointer { normalizedMagnitudes in
-        vDSP_vsmulD(sqrt(magnitudes), 1, [2.0 / Double(input.count)], normalizedMagnitudes.baseAddress!, 1, vDSP_Length(input.count))
-    }
-
-    vDSP_destroy_fftsetupD(weights)
-
-    return normalizedMagnitudes
 }