Added xdsp content

Deinterleave.md

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+Deinterleaves audio samples such that all samples corresponding to a given channel are contiguous.
+
+    void Deinterleave(XMVECTOR* pOutput, const XMVECTOR* pInput,
+        const size_t uChannelCount, const size_t uFrameCount);
+# Parameters
+## pOutput
+[out] Caller-provided array of XVECTOR elements that receives the samples in deinterleaved form. It cannot overlap pInput and it must have at least (uChannelCount × uFrameCount) ÷ 4 elements. 
+
+## pInput
+[in] Caller-provided array of XVECTOR elements that supplies audio samples in interleaved form. It cannot overlap pOutput and it must have at least (uChannelCount × uFrameCount) ÷ 4 elements. 
+
+## uChannelCount
+[in] The number of channels contained in the data. uChannelCount must be greater than 1. 
+
+## uFrameCount
+[in] The number of frames of valid data. uFrameCount must be greater than 0. 
+
+# Remarks
+For example, audio of the form [LRLRLR] becomes [LLLRRR].

FFT.md

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+Fast Fourier Transform with an arbitrary number of samples.
+
+    void FFT(XMVECTOR* pReal, XMVECTOR* pImaginary,
+            const XMVECTOR* pUnityTable,
+            const size_t uLength, const size_t uCount=1);
+# Parameters
+
+## pReal
+[in, out] Real components of the FFT. Must have as least (uLength × uCount) ÷ 4 elements. 
+
+## pImaginary
+[in, out] Imaginary components of the FFT. Must have at least (uLength × uCount) ÷ 4 elements. 
+
+## pUnityTable
+[in] Unity table the FFT should use. Must have at least uLength × uCount XVECTORs. See [[FFTInitializeUnityTable]] for more information. 
+
+## uLength
+[in] FFT length in samples. uLength must be a power of two and must be greater than 16. 
+
+## uCount
+[in] Number of FFT iterations. 
+
+# Remarks
+For FFTs with a number of samples less than or equal to 16 use [[FFT16]], [[FFT8]] or [[FFT4]].
+
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.
+

FFT16.md

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+Fast Fourier Transform with sixteen samples.
+
+    void FFT16(XMVECTOR* pReal, XMVECTOR* pImaginary, const size_t uCount=1);
+# Parameters
+## pReal
+[in, out] Real components of the FFT. Must have as least uCount × 4 elements. 
+
+## pImaginary
+[in, out] Imaginary components of the FFT. Must have at least uCount × 4 elements. 
+
+## uCount
+[in] Number of FFT iterations. 
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.
+

FFT4.md

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+Fast Fourier Transform with four samples.
+
+    void FFT4(XMVECTOR* pReal, XMVECTOR* pImaginary, const size_t uCount=1);
+
+# Parameters
+## pReal
+[in, out] Real components of the FFT. Must have as least uCount elements. 
+
+## pImaginary
+[in, out] Imaginary components of the FFT. Must have at least uCount elements. 
+
+## uCount
+[in] Number of FFT iterations. 
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.
+

FFT8.md

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+Fast Fourier Transform with eight samples.
+
+    void FFT8 (XMVECTOR* pReal, XMVECTOR* pImaginary, const size_t uCount=1);
+# Parameters
+## pReal
+[in, out] Real components of the FFT. Must have as least uCount × 2 elements. 
+
+## pImaginary
+[in, out] Imaginary components of the FFT. Must have at least uCount × 2 elements. 
+
+## uCount
+[in] Number of FFT iterations. 
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.

FFTInitializeUnityTable.md

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+Initializes unity roots lookup table used by Fast Fourier Transform functions.
+
+    void FFTInitializeUnityTable(XMVECTOR* pUnityTable, size_t uLength);
+# Parameters
+## pUnityTable
+[out] Caller-provided array of XVECTOR elements that will be populated with the unity table values. The array passed to pUnityTable must be at least uLength elements long. 
+
+## uLength
+[in] The FFT length in frames (sample count / channel count). uLength must be a power of two and must be greater than 16. 
+
+# Remarks
+Once initialized, the table does not need to be initialized again unless you want a different FFT length.
+
+Unity tables for FFT lengths of 16 and below are hard coded into the respective [[FFT]] functions ([[FFT16]], [[FFT8]], and [[FFT4]]). They do not need to be initialized.
+
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.

FFTInterleaved.md

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+This function applies a 2N-sample Fast Fourier Transform, and unswizzles the result such that the samples are in order of increasing frequency. Audio is first deinterleaved if it is multichannel. 
+
+    void FFTInterleaved(XMVECTOR* pReal, XMVECTOR* pImaginary,
+        const XMVECTOR* pUnityTable,
+        const size_t uChannelCount, const size_t uLog2Length);
+# Parameters
+## pReal
+[in, out] Real components of the FFT. Must have as least (1 << uLog2Length × uChannelCount) ÷ 4 elements.
+ 
+## pImaginary
+[out] Imaginary components of the FFT. Must have at least (1 << uLog2Length × uChannelCount) ÷ 4 elements.
+ 
+## pUnityTable
+[in] Unity table the FFT should use. Must have at least (1 << uLog2Length) elements. See [[FFTInitializeUnityTable]] for more information. 
+
+## uChannelCount
+[in] Number of channels in the FFT. uChannelCount must be within [1,6]. 
+
+## uLog2Length
+[in] Log (base 2) of FFT length in frames. uLog2Length must be within [2, 9].  
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.

FFTPolar.md

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+Converts complex components to polar form.
+
+    void FFTPolar(XMVECTOR* pOutput,
+        const XMVECTOR* pInputReal, const XMVECTOR* pInputImaginary,
+        const size_t uLength);
+# Parameters
+## pOutput
+[out] Caller supplied output buffer to receive samples in polar form. pOutput must have at least uLength ÷ 4 elements. 
+
+## pInputReal
+[in] Input buffer containing the real components of a Fast Fourier Transform. pInputReal must have at least uLength ÷ 4 elements. 
+
+## pInputImaginary
+[in] Input buffer containing the imaginary components of an FFT. pInputImaginary must have at least uLength ÷ 4 elements. 
+
+## uLength
+[in] FFT length in samples. uLength must be a power of 2 greater than or equal to 4. 
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.
+

FFTUnswizzle.md

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+Arranges Fast Fourier Transform function output by order of increasing frequency.
+
+    void FFTUnswizzle(XMVECTOR* pOutput, const XMVECTOR* pInput,
+         const size_t uLog2Length);
+# Parameters
+## pOutput
+[out] Caller-supplied output buffer. pOutput receives samples in order of increasing frequency. The buffer must have at least 1<<uLog2Length/4 elements. 
+
+## pInput
+[in] Input buffer containing samples in bit-reversed order as generated by FFT functions. The buffer must have at least 1<<uLog2Length/4 elements. 
+
+## uLog2Length
+[in] The log base 2 of the FFT length in samples. uLog2Length must be greater than or equal to 2. 
+
+# Remarks
+The FFT functions generate output in bit-reversed order. Use FFTUnswizzle to rearrange FFT function output into order of increasing frequency.
+
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.
+

IFFTDeinterleaved.md

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+This function applies a 2N-sample inverse Fast Fourier Transform. Audio is first interleaved if it is multichannel. 
+
+    void IFFTDeinterleaved(XMVECTOR* pReal, const XMVECTOR* pImaginary,
+                           const XMVECTOR* pUnityTable,
+                           const size_t uChannelCount, const size_t uLog2Length);
+# Parameters
+## pReal
+[in, out] Real components of the FFT. It must have at least (1 << uLog2Length × uChannelCount) ÷ 4 elements. 
+
+# pImaginary
+[in] Imaginary components of the FFT. It must have at least (1 << uLog2Length × uChannelCount) ÷ 4 elements. 
+
+# pUnityTable
+[in] Unity table the FFT should use. It must have at least (1 << uLog2Length) elements. See FFTInitializeUnityTable for more information. 
+
+# uChannelCount
+[in] Number of channels in the FFT. uChannelCount must be greater than zero. 
+
+# uLog2Length
+[in] Log (base 2) of FFT length in frames. uLog2Length must be within [2, 10].
+
+# Remarks
+All buffer parameters must be 16-byte aligned. Audio data must be 32-bit float mono.

Interleave.md

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+Interleaves audio samples such that all samples corresponding to a given frame are contiguous.
+
+    void Interleave (XMVECTOR* pOutput, const XMVECTOR* pInput,
+        const size_t uChannelCount, const size_t uFrameCount);
+# Parameters
+# pOutput
+[out] Caller-provided array of XVECTOR elements that receives the samples in interleaved form. It cannot overlap pInput and it must have at least (uChannelCount × uFrameCount) ÷ 4 elements. 
+
+# pInput
+[in] Caller-provided array of XVECTOR elements that supplies audio samples in deinterleaved form. It cannot overlap pOutput and it must have at least (uChannelCount × uFrameCount) ÷ 4 elements. 
+
+# uChannelCount
+[in] The number of channels contained in the data. uChannelCount must be greater than 1. 
+
+# uFrameCount
+[in] The number of frames of valid data. uFrameCount must be greater than 0. 
+
+# Remarks
+For example, audio of the form [LLLRRR] becomes [LRLRLR].