Alexandre Lision | 7c6f4a6 | 2013-09-05 13:27:01 -0400 | [diff] [blame] | 1 | /* |
| 2 | ** Copyright (C) 2002-2011 Erik de Castro Lopo <erikd@mega-nerd.com> |
| 3 | ** |
| 4 | ** This program is free software; you can redistribute it and/or modify |
| 5 | ** it under the terms of the GNU General Public License as published by |
| 6 | ** the Free Software Foundation; either version 2 of the License, or |
| 7 | ** (at your option) any later version. |
| 8 | ** |
| 9 | ** This program is distributed in the hope that it will be useful, |
| 10 | ** but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | ** GNU General Public License for more details. |
| 13 | ** |
| 14 | ** You should have received a copy of the GNU General Public License |
| 15 | ** along with this program; if not, write to the Free Software |
| 16 | ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | */ |
| 18 | |
| 19 | #include <stdio.h> |
| 20 | #include <stdlib.h> |
| 21 | #include <math.h> |
| 22 | |
| 23 | #include "dft_cmp.h" |
| 24 | #include "utils.h" |
| 25 | |
| 26 | #ifndef M_PI |
| 27 | #define M_PI 3.14159265358979323846264338 |
| 28 | #endif |
| 29 | |
| 30 | #define DFT_SPEC_LENGTH (DFT_DATA_LENGTH / 2) |
| 31 | |
| 32 | static void dft_magnitude (const double *data, double *spectrum) ; |
| 33 | static double calc_max_spectral_difference (const double *spec1, const double *spec2) ; |
| 34 | |
| 35 | /*-------------------------------------------------------------------------------- |
| 36 | ** Public functions. |
| 37 | */ |
| 38 | |
| 39 | double |
| 40 | dft_cmp_float (int linenum, const float *in_data, const float *test_data, int len, double target_snr, int allow_exit) |
| 41 | { static double orig [DFT_DATA_LENGTH] ; |
| 42 | static double test [DFT_DATA_LENGTH] ; |
| 43 | unsigned k ; |
| 44 | |
| 45 | if (len != DFT_DATA_LENGTH) |
| 46 | { printf ("Error (line %d) : dft_cmp_float : Bad input array length.\n", linenum) ; |
| 47 | return 1 ; |
| 48 | } ; |
| 49 | |
| 50 | for (k = 0 ; k < ARRAY_LEN (orig) ; k++) |
| 51 | { test [k] = test_data [k] ; |
| 52 | orig [k] = in_data [k] ; |
| 53 | } ; |
| 54 | |
| 55 | return dft_cmp_double (linenum, orig, test, len, target_snr, allow_exit) ; |
| 56 | } /* dft_cmp_float */ |
| 57 | |
| 58 | double |
| 59 | dft_cmp_double (int linenum, const double *orig, const double *test, int len, double target_snr, int allow_exit) |
| 60 | { static double orig_spec [DFT_SPEC_LENGTH] ; |
| 61 | static double test_spec [DFT_SPEC_LENGTH] ; |
| 62 | double snr ; |
| 63 | |
| 64 | if (! orig || ! test) |
| 65 | { printf ("Error (line %d) : dft_cmp_double : Bad input arrays.\n", linenum) ; |
| 66 | return 1 ; |
| 67 | } ; |
| 68 | |
| 69 | if (len != DFT_DATA_LENGTH) |
| 70 | { printf ("Error (line %d) : dft_cmp_double : Bad input array length.\n", linenum) ; |
| 71 | return 1 ; |
| 72 | } ; |
| 73 | |
| 74 | dft_magnitude (orig, orig_spec) ; |
| 75 | dft_magnitude (test, test_spec) ; |
| 76 | |
| 77 | snr = calc_max_spectral_difference (orig_spec, test_spec) ; |
| 78 | |
| 79 | if (snr > target_snr) |
| 80 | { printf ("\n\nLine %d: Actual SNR (% 4.1f) > target SNR (% 4.1f).\n\n", linenum, snr, target_snr) ; |
| 81 | oct_save_double (orig, test, len) ; |
| 82 | if (allow_exit) |
| 83 | exit (1) ; |
| 84 | } ; |
| 85 | |
| 86 | if (snr < -500.0) |
| 87 | snr = -500.0 ; |
| 88 | |
| 89 | return snr ; |
| 90 | } /* dft_cmp_double */ |
| 91 | |
| 92 | /*-------------------------------------------------------------------------------- |
| 93 | ** Quick dirty calculation of magnitude spectrum for real valued data using |
| 94 | ** Discrete Fourier Transform. Since the data is real, the DFT is only |
| 95 | ** calculated for positive frequencies. |
| 96 | */ |
| 97 | |
| 98 | static void |
| 99 | dft_magnitude (const double *data, double *spectrum) |
| 100 | { static double cos_angle [DFT_DATA_LENGTH] = { 0.0 } ; |
| 101 | static double sin_angle [DFT_DATA_LENGTH] ; |
| 102 | |
| 103 | double real_part, imag_part ; |
| 104 | int k, n ; |
| 105 | |
| 106 | /* If sine and cosine tables haven't been initialised, do so. */ |
| 107 | if (cos_angle [0] == 0.0) |
| 108 | for (n = 0 ; n < DFT_DATA_LENGTH ; n++) |
| 109 | { cos_angle [n] = cos (2.0 * M_PI * n / DFT_DATA_LENGTH) ; |
| 110 | sin_angle [n] = -1.0 * sin (2.0 * M_PI * n / DFT_DATA_LENGTH) ; |
| 111 | } ; |
| 112 | |
| 113 | /* DFT proper. Since the data is real, only generate a half spectrum. */ |
| 114 | for (k = 1 ; k < DFT_SPEC_LENGTH ; k++) |
| 115 | { real_part = 0.0 ; |
| 116 | imag_part = 0.0 ; |
| 117 | |
| 118 | for (n = 0 ; n < DFT_DATA_LENGTH ; n++) |
| 119 | { real_part += data [n] * cos_angle [(k * n) % DFT_DATA_LENGTH] ; |
| 120 | imag_part += data [n] * sin_angle [(k * n) % DFT_DATA_LENGTH] ; |
| 121 | } ; |
| 122 | |
| 123 | spectrum [k] = sqrt (real_part * real_part + imag_part * imag_part) ; |
| 124 | } ; |
| 125 | |
| 126 | spectrum [k] = 0.0 ; |
| 127 | |
| 128 | spectrum [0] = spectrum [1] = spectrum [2] = spectrum [3] = spectrum [4] = 0.0 ; |
| 129 | |
| 130 | return ; |
| 131 | } /* dft_magnitude */ |
| 132 | |
| 133 | static double |
| 134 | calc_max_spectral_difference (const double *orig, const double *test) |
| 135 | { double orig_max = 0.0, max_diff = 0.0 ; |
| 136 | int k ; |
| 137 | |
| 138 | for (k = 0 ; k < DFT_SPEC_LENGTH ; k++) |
| 139 | { if (orig_max < orig [k]) |
| 140 | orig_max = orig [k] ; |
| 141 | if (max_diff < fabs (orig [k] - test [k])) |
| 142 | max_diff = fabs (orig [k] - test [k]) ; |
| 143 | } ; |
| 144 | |
| 145 | if (max_diff < 1e-25) |
| 146 | return -500.0 ; |
| 147 | |
| 148 | return 20.0 * log10 (max_diff / orig_max) ; |
| 149 | } /* calc_max_spectral_difference */ |