From 963b6e257a447e7a5cca9c3050bad6defb88f647 Mon Sep 17 00:00:00 2001
From: Jared Boone <jboone@earfeast.com>
Date: Sun, 3 Jan 2016 20:25:31 -0800
Subject: [PATCH] FFT twiddles can be used for all K <= table length.

Change assert to allow FFTs < 8.
---
 firmware/common/dsp_fft.hpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/firmware/common/dsp_fft.hpp b/firmware/common/dsp_fft.hpp
index f61218d0..7d4c61e1 100644
--- a/firmware/common/dsp_fft.hpp
+++ b/firmware/common/dsp_fft.hpp
@@ -111,8 +111,9 @@ void fft_c_preswapped(std::array<T, N>& data) {
 	static_assert(power_of_two(N), "only defined for N == power of two");
 	constexpr auto K = log_2(N);
 
-	static_assert(N == 256, "lame that I've hard-coded a table for K=8");
-	static constexpr std::array<std::complex<float>, K> wp_table { {
+	constexpr size_t K_max = 8;
+	static_assert(K <= K_max, "No FFT twiddle factors for K > 8");
+	static constexpr std::array<std::complex<float>, K_max> wp_table { {
 		{ -2.00000000000000000000000000000000f,  0.00000000000000000000000000000000f },
 		{ -1.00000000000000000000000000000000f, -1.00000000000000000000000000000000f },
 		{ -0.29289321881345242726268907063059f, -0.70710678118654746171500846685376f },