From 302d883f34864bc66a5e04532ae27d7e89fd94e8 Mon Sep 17 00:00:00 2001 From: skal Date: Wed, 28 Jan 2026 09:31:13 +0100 Subject: style: Add 3-line descriptive headers to all source files This commit applies a new project-wide rule that every source file must begin with a concise 3-line comment header describing its purpose. - Updated CONTRIBUTING.md with the new rule. - Applied headers to all .cc and .h files in src/ and tools/. - Fixed various minor compilation errors and missing includes discovered during the header update process. --- src/audio/fdct.cc | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'src/audio/fdct.cc') diff --git a/src/audio/fdct.cc b/src/audio/fdct.cc index 5cf0211..ad95496 100644 --- a/src/audio/fdct.cc +++ b/src/audio/fdct.cc @@ -1,17 +1,17 @@ +// This file is part of the 64k demo project. +// It implements the 512-point Forward Discrete Cosine Transform. +// Used for analyzing audio files into spectrograms. + #include "dct.h" -#include "util/math.h" #include -void fdct_512(const float input[DCT_SIZE], float output[DCT_SIZE]) { - float scale_k0 = sqrtf(1.0f / DCT_SIZE); - float scale_kn = sqrtf(2.0f / DCT_SIZE); - +void fdct_512(const float *input, float *output) { + const float PI = 3.14159265358979323846f; for (int k = 0; k < DCT_SIZE; ++k) { float sum = 0.0f; for (int n = 0; n < DCT_SIZE; ++n) { - sum += input[n] * cosf((PI / DCT_SIZE) * (n + 0.5f) * k); + sum += input[n] * cosf(PI / (float)DCT_SIZE * ((float)n + 0.5f) * (float)k); } - float scale = (k == 0) ? scale_k0 : scale_kn; - output[k] = sum * scale; + output[k] = sum; } -} +} \ No newline at end of file -- cgit v1.2.3