onepole-float.h

   1 /*
   2 Calf Box, an open source musical instrument.
   3 Copyright (C) 2010 Krzysztof Foltman
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, either version 3 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #ifndef CBOX_ONEPOLE_FLOAT_H
  20 #define CBOX_ONEPOLE_FLOAT_H
  21
  22 #include "dspmath.h"
  23
  24 struct cbox_onepolef_state
  25 {
  26     float x1;
  27     float y1;
  28 };
  29
  30 struct cbox_onepolef_coeffs
  31 {
  32     float a0;
  33     float a1;
  34     float b1;
  35 };
  36
  37 static inline void cbox_onepolef_reset(struct cbox_onepolef_state *state)
  38 {
  39     state->x1 = state->y1 = 0.f;
  40 }
  41
  42 static inline void cbox_onepolef_set_lowpass(struct cbox_onepolef_coeffs *coeffs, float w)
  43 {
  44     float x = tan (w * 0.5f);
  45     float q = 1 / (1 + x);
  46     float a01 = x*q;
  47     float b1 = a01 - q;
  48
  49     coeffs->a0 = a01;
  50     coeffs->a1 = a01;
  51     coeffs->b1 = b1;
  52 }
  53
  54 static inline void cbox_onepolef_set_highpass(struct cbox_onepolef_coeffs *coeffs, float w)
  55 {
  56     float x = tan (w * 0.5f);
  57     float q = 1 / (1 + x);
  58     float a01 = x*q;
  59     float b1 = a01 - q;
  60
  61     coeffs->a0 = q;
  62     coeffs->a1 = -q;
  63     coeffs->b1 = b1;
  64 }
  65
  66 static inline void cbox_onepolef_set_allpass(struct cbox_onepolef_coeffs *coeffs, float w)
  67 {
  68     float x = tan (w * 0.5f);
  69     float q = 1 / (1 + x);
  70     float a01 = x*q;
  71     float b1 = a01 - q;
  72
  73     coeffs->a0 = b1;
  74     coeffs->a1 = 1;
  75     coeffs->b1 = b1;
  76 }
  77
  78 static inline float cbox_onepolef_process_sample(struct cbox_onepolef_state *state, struct cbox_onepolef_coeffs *coeffs, float in)
  79 {
  80     float out = sanef(coeffs->a0 * in + coeffs->a1 * state->x1 - coeffs->b1 * state->y1);
  81
  82     state->x1 = in;
  83     state->y1 = out;
  84     return out;
  85 }
  86
  87 static inline void cbox_onepolef_process(struct cbox_onepolef_state *state, struct cbox_onepolef_coeffs *coeffs, float *buffer)
  88 {
  89     int i;
  90     float a0 = coeffs->a0;
  91     float a1 = coeffs->a1;
  92     float b1 = coeffs->b1;
  93
  94     for (i = 0; i < CBOX_BLOCK_SIZE; i++)
  95     {
  96         float in = buffer[i];
  97         double out = a0 * in + a1 * state->x1 - b1 * state->y1;
  98
  99         buffer[i] = out;
 100         state->x1 = in;
 101         state->y1 = out;
 102     }
 103     state->y1 = sanef(state->y1);
 104 }
 105
 106 static inline void cbox_onepolef_process_to(struct cbox_onepolef_state *state, struct cbox_onepolef_coeffs *coeffs, float *buffer_in, float *buffer_out)
 107 {
 108     int i;
 109     float a0 = coeffs->a0;
 110     float a1 = coeffs->a1;
 111     float b1 = coeffs->b1;
 112
 113     for (i = 0; i < CBOX_BLOCK_SIZE; i++)
 114     {
 115         float in = buffer_in[i];
 116         double out = a0 * in + a1 * state->x1 - b1 * state->y1;
 117
 118         buffer_out[i] = out;
 119         state->x1 = in;
 120         state->y1 = out;
 121     }
 122     state->y1 = sanef(state->y1);
 123 }
 124
 125 #endif