From 882fbbef3182973be53e06107580478c7f7e4df3 Mon Sep 17 00:00:00 2001
From: Jared Boone <jboone@earfeast.com>
Date: Thu, 17 Sep 2015 17:27:37 -0700
Subject: [PATCH] Add more fft_swap bit reversal functions.

---
 firmware/common/dsp_fft.hpp | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/firmware/common/dsp_fft.hpp b/firmware/common/dsp_fft.hpp
index 5fbf08428..3f88b6a3d 100644
--- a/firmware/common/dsp_fft.hpp
+++ b/firmware/common/dsp_fft.hpp
@@ -29,6 +29,7 @@
 #include <type_traits>
 #include <array>
 
+#include "dsp_types.hpp"
 #include "complex.hpp"
 #include "hal.h"
 
@@ -54,6 +55,20 @@ constexpr size_t log_2(const size_t n, const size_t p = 0) {
 	return (n <= 1) ? p : log_2(n / 2, p + 1);
 }
 
+template<typename T, size_t N>
+void fft_swap(const buffer_c16_t src, std::array<T, N>& dst) {
+	static_assert(power_of_two(N), "only defined for N == power of two");
+
+	for(size_t i=0; i<N; i++) {
+		const size_t i_rev = __RBIT(i) >> (32 - log_2(N));
+		const auto s = src.p[i];
+		dst[i_rev] = {
+			static_cast<typename T::value_type>(s.real()),
+			static_cast<typename T::value_type>(s.imag())
+		};
+	}
+}
+
 template<typename T, size_t N>
 void fft_swap(const std::array<complex16_t, N>& src, std::array<T, N>& dst) {
 	static_assert(power_of_two(N), "only defined for N == power of two");
@@ -69,10 +84,20 @@ void fft_swap(const std::array<complex16_t, N>& src, std::array<T, N>& dst) {
 }
 
 template<typename T, size_t N>
-void fft_swap_in_place(std::array<T, N>& data) {
+void fft_swap(const std::array<T, N>& src, std::array<T, N>& dst) {
 	static_assert(power_of_two(N), "only defined for N == power of two");
 
 	for(size_t i=0; i<N; i++) {
+		const size_t i_rev = __RBIT(i) >> (32 - log_2(N));
+		dst[i_rev] = src[i];
+	}
+}
+
+template<typename T, size_t N>
+void fft_swap_in_place(std::array<T, N>& data) {
+	static_assert(power_of_two(N), "only defined for N == power of two");
+
+	for(size_t i=0; i<N/2; i++) {
 		const size_t i_rev = __RBIT(i) >> (32 - log_2(N));
 		std::swap(data[i], data[i_rev]);
 	}