initial commit

spectrum_buffer_manager_class.cpp

@@ -0,0 +1,137 @@
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_image.h>
+#include <SDL2/SDL_timer.h>
+#include <SDL2/SDL_ttf.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <cmath>
+#include <unistd.h>
+#include <iostream>
+#include <chrono>
+#include <pulse/simple.h>
+#include <pulse/error.h>
+#include <fftw3.h>
+#include "scope.h"
+
+spectrum_buffer_manager_class::spectrum_buffer_manager_class()
+  {
+  my_formatted_spectrum_buffer = NULL;
+  }
+
+spectrum_buffer_manager_class::~spectrum_buffer_manager_class()
+  {
+  if (my_formatted_spectrum_buffer != NULL)
+    {
+    free(my_formatted_spectrum_buffer);
+    }
+  }
+
+int spectrum_buffer_manager_class::initialize_spectrum(int horizontal_size,
+  int vertical_size, Sint16 *main_buffer)
+  {
+  // This is the formatted buffer that will be fed to the display 
+  my_formatted_spectrum_buffer = (int *)malloc ((sizeof(int) * AUDIO_BUFFER_SIZE));
+  if (my_formatted_spectrum_buffer == NULL)
+    {
+    printf ("cannot allocate formatted spectrum spectrum buffer\n");
+    perror ("error is");
+    return 1;
+    }
+
+  //Allocate output fftw buffer
+  if ((output_fftw = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) 
+    * FFT_BUFFER_SIZE * 2)) == NULL)
+    {
+    printf ("cannot allocate fftw output buffer\n");
+    perror ("error is");
+    return 1;
+    }
+
+  //Allocate input fftw buffer
+  if ((input_fftw = (double*) fftw_malloc(sizeof(double) * FFT_BUFFER_SIZE)) == NULL)
+    {
+    printf ("cannot allocate fftw input buffer\n");
+    perror ("error is");
+    return 1;
+    }
+
+  // Now lets attempt to perform an fftw plan
+  if ((my_fftw_plan = fftw_plan_dft_r2c_1d(FFT_BUFFER_SIZE, input_fftw,
+    output_fftw, FFTW_MEASURE)) == NULL) 
+    {
+    printf ("cannot fftw plan");
+    perror ("error is");
+    return 1;
+    }
+
+  // my_read_spectrum_index is which chunk we will put the read buffer into
+  my_read_spectrum_index = 0;
+
+  // index to read the individual elements into the fftw input buffer
+  read_buffer_counter = 0;
+
+  // my_output_fft_buffer_index is used to flip output buffer
+  // members all to negative for display purposes 
+
+  my_output_fft_buffer_index = 0;
+
+  my_spectrum_horizontal_size = horizontal_size;
+  my_spectrum_vertical_size = vertical_size; 
+ 
+  // The main buffer is the read buffer from main buffer read
+  my_main_buffer = main_buffer;
+  return 0;
+  }
+
+// Returns address for formatted fft buffer for ready to display
+// Return NULL for waiting for buffer fill
+int *spectrum_buffer_manager_class::process_spectrum()
+  {
+  // Fill the fftw input array
+  // Fill in section corresponging to the current read_buffer_counter
+  input_fftw_write_position = input_fftw + my_read_spectrum_index;
+  for (read_buffer_counter = 0; read_buffer_counter < READ_BUFFER_SIZE;
+   read_buffer_counter += 1)
+    {
+    main_buffer_hold =  (Sint16)(*(my_main_buffer + read_buffer_counter) * SPECTRUM_VOLUME);
+    *(input_fftw_write_position + read_buffer_counter) = (double)main_buffer_hold;
+    }
+
+  /* prep for next time */
+  my_read_spectrum_index += 1;
+  // Are we still working on filling this buffer?
+  if (my_read_spectrum_index < FFT_NUMBER_READ_BUFFERS)
+    {
+    // Lets wait 
+    return NULL; 
+    }
+  else
+    // Done filling up fft buffer - lets process
+    {
+    // First, reset the spectrum index to 0
+    my_read_spectrum_index = 0;
+    
+    // Perform the fft
+    fftw_execute(my_fftw_plan);
+
+    // Now grab the real part of the complex output
+    for (my_output_fft_buffer_index = 0;
+     my_output_fft_buffer_index < my_spectrum_horizontal_size;
+     my_output_fft_buffer_index += 1)
+      {
+      *(my_formatted_spectrum_buffer + my_output_fft_buffer_index)
+       = (int)(output_fftw[(FFT_START_BUCKET + 
+       (my_output_fft_buffer_index))][0] * SPECTRUM_VOLUME);
+      if (*(my_formatted_spectrum_buffer + my_output_fft_buffer_index) > 0 )
+        {
+        // Flip any positive values to negative because negative causes location
+        // to go up on the sdl coordinate system
+        *(my_formatted_spectrum_buffer + my_output_fft_buffer_index) =
+        - *(my_formatted_spectrum_buffer + my_output_fft_buffer_index);
+        }
+      }
+    }
+
+  return my_formatted_spectrum_buffer;
+  }
+