LIB: IFFTSynth: simplify quantized freq computation (performance)

Signed-off-by: Stefan Westerfeld <[email protected]>
swesterfeld · Jun 7, 2024 · a9b5a01 · a9b5a01
1 parent 150ed96
commit a9b5a01
Show file tree

Hide file tree

Showing 2 changed files with 4 additions and 7 deletions.
diff --git a/lib/smifftsynth.cc b/lib/smifftsynth.cc
@@ -23,8 +23,7 @@ namespace SpectMorph {
 }
 
 IFFTSynth::IFFTSynth (size_t block_size, double mix_freq, WindowType win_type) :
-  block_size (block_size),
-  mix_freq (mix_freq)
+  block_size (block_size)
 {
   std::lock_guard lg (table_mutex);
 
@@ -86,6 +85,7 @@ IFFTSynth::IFFTSynth (size_t block_size, double mix_freq, WindowType win_type) :
   fft_in = FFT::new_array_float (block_size);
   fft_out = FFT::new_array_float (block_size);
   freq256_factor = 1 / mix_freq * block_size * zero_padding;
+  freq256_to_qfreq = mix_freq / 256.0 / block_size;
   mag_norm = 0.5 / block_size;
 }
 

diff --git a/lib/smifftsynth.hh b/lib/smifftsynth.hh
@@ -18,8 +18,8 @@ class IFFTSynth
 
   int                zero_padding;
   size_t             block_size;
-  float              mix_freq;
   float              freq256_factor;
+  float              freq256_to_qfreq;
   float              mag_norm;
 
   float             *fft_in;
@@ -152,10 +152,7 @@ inline float
 IFFTSynth::quantized_freq (float mf_freq)
 {
   const int freq256 = sm_round_positive (mf_freq * freq256_factor);
-  const float qfreq = freq256 * float (1 / 256.0);
-  const float mf_qfreq = qfreq / block_size * mix_freq;
-
-  return mf_qfreq;
+  return freq256 * freq256_to_qfreq;
 }
 
 }