/* -*- linux-c -*- Copyright (C) 2004 Tom Szilagyi This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. $Id: tap_utils.h,v 1.5 2004/02/21 17:33:36 tszilagyi Exp $ */ #ifndef _ISOC99_SOURCE #define _ISOC99_SOURCE #endif #include #ifndef M_PI #define M_PI 3.14159265358979323846264338327 #endif /* push a sample into a ringbuffer and return the sample falling out */ static inline LADSPA_Data push_buffer(LADSPA_Data insample, LADSPA_Data * buffer, unsigned long buflen, unsigned long * pos) { LADSPA_Data outsample; outsample = buffer[*pos]; buffer[(*pos)++] = insample; if (*pos >= buflen) *pos = 0; return outsample; } /* read a value from a ringbuffer. * n == 0 returns the oldest sample from the buffer. * n == buflen-1 returns the sample written to the buffer * at the last push_buffer call. * n must not exceed buflen-1, or your computer will explode. */ static inline LADSPA_Data read_buffer(LADSPA_Data * buffer, unsigned long buflen, unsigned long pos, unsigned long n) { while (n + pos >= buflen) n -= buflen; return buffer[n + pos]; } /* overwrites a value in a ringbuffer, but pos stays the same. * n == 0 overwrites the oldest sample pushed in the buffer. * n == buflen-1 overwrites the sample written to the buffer * at the last push_buffer call. * n must not exceed buflen-1, or your computer... you know. */ static inline void write_buffer(LADSPA_Data insample, LADSPA_Data * buffer, unsigned long buflen, unsigned long pos, unsigned long n) { while (n + pos >= buflen) n -= buflen; buffer[n + pos] = insample; } /* Please note that the majority of the definitions and helper functions below have been derived from the source code of Steve Harris's SWH plugins (particularly from the "biquad.h" file). While I give him credit for his excellent work, I reserve myself to be blamed for any bugs or malfunction. */ #define db2lin(x) ((x) > -90.0f ? powf(10.0f, (x) * 0.05f) : 0.0f) #define ABS(x) (x)>0.0f?(x):-1.0f*(x) #define LN_2_2 0.34657359f #define LIMIT(v,l,u) ((v)<(l)?(l):((v)>(u)?(u):(v))) #define BIQUAD_TYPE float typedef BIQUAD_TYPE bq_t; /* Biquad filter (adapted from lisp code by Eli Brandt, http://www.cs.cmu.edu/~eli/) */ /* The prev. comment has been preserved from Steve Harris's biquad.h */ typedef struct { bq_t a1; bq_t a2; bq_t b0; bq_t b1; bq_t b2; bq_t x1; bq_t x2; bq_t y1; bq_t y2; } biquad; static inline void biquad_init(biquad *f) { f->x1 = 0.0f; f->x2 = 0.0f; f->y1 = 0.0f; f->y2 = 0.0f; } static inline void eq_set_params(biquad *f, bq_t fc, bq_t gain, bq_t bw, bq_t fs) { bq_t w = 2.0f * M_PI * LIMIT(fc, 1.0f, fs/2.0f) / fs; bq_t cw = cosf(w); bq_t sw = sinf(w); bq_t J = pow(10.0f, gain * 0.025f); bq_t g = sw * sinhf(LN_2_2 * LIMIT(bw, 0.0001f, 4.0f) * w / sw); bq_t a0r = 1.0f / (1.0f + (g / J)); f->b0 = (1.0f + (g * J)) * a0r; f->b1 = (-2.0f * cw) * a0r; f->b2 = (1.0f - (g * J)) * a0r; f->a1 = -(f->b1); f->a2 = ((g / J) - 1.0f) * a0r; } static inline void lp_set_params(biquad *f, bq_t fc, bq_t bw, bq_t fs) { bq_t omega = 2.0 * M_PI * fc/fs; bq_t sn = sin(omega); bq_t cs = cos(omega); bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn); const float a0r = 1.0 / (1.0 + alpha); #if 0 b0 = (1 - cs) /2; b1 = 1 - cs; b2 = (1 - cs) /2; a0 = 1 + alpha; a1 = -2 * cs; a2 = 1 - alpha; #endif f->b0 = a0r * (1.0 - cs) * 0.5; f->b1 = a0r * (1.0 - cs); f->b2 = a0r * (1.0 - cs) * 0.5; f->a1 = a0r * (2.0 * cs); f->a2 = a0r * (alpha - 1.0); } static inline void hp_set_params(biquad *f, bq_t fc, bq_t bw, bq_t fs) { bq_t omega = 2.0 * M_PI * fc/fs; bq_t sn = sin(omega); bq_t cs = cos(omega); bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn); const float a0r = 1.0 / (1.0 + alpha); #if 0 b0 = (1 + cs) /2; b1 = -(1 + cs); b2 = (1 + cs) /2; a0 = 1 + alpha; a1 = -2 * cs; a2 = 1 - alpha; #endif f->b0 = a0r * (1.0 + cs) * 0.5; f->b1 = a0r * -(1.0 + cs); f->b2 = a0r * (1.0 + cs) * 0.5; f->a1 = a0r * (2.0 * cs); f->a2 = a0r * (alpha - 1.0); } static inline void ls_set_params(biquad *f, bq_t fc, bq_t gain, bq_t slope, bq_t fs) { bq_t w = 2.0f * M_PI * LIMIT(fc, 1.0, fs/2.0) / fs; bq_t cw = cosf(w); bq_t sw = sinf(w); bq_t A = powf(10.0f, gain * 0.025f); bq_t b = sqrt(((1.0f + A * A) / LIMIT(slope, 0.0001f, 1.0f)) - ((A - 1.0f) * (A - 1.0))); bq_t apc = cw * (A + 1.0f); bq_t amc = cw * (A - 1.0f); bq_t bs = b * sw; bq_t a0r = 1.0f / (A + 1.0f + amc + bs); f->b0 = a0r * A * (A + 1.0f - amc + bs); f->b1 = a0r * 2.0f * A * (A - 1.0f - apc); f->b2 = a0r * A * (A + 1.0f - amc - bs); f->a1 = a0r * 2.0f * (A - 1.0f + apc); f->a2 = a0r * (-A - 1.0f - amc + bs); } static inline void hs_set_params(biquad *f, bq_t fc, bq_t gain, bq_t slope, bq_t fs) { bq_t w = 2.0f * M_PI * LIMIT(fc, 1.0, fs/2.0) / fs; bq_t cw = cosf(w); bq_t sw = sinf(w); bq_t A = powf(10.0f, gain * 0.025f); bq_t b = sqrt(((1.0f + A * A) / LIMIT(slope, 0.0001f, 1.0f)) - ((A - 1.0f) * (A - 1.0f))); bq_t apc = cw * (A + 1.0f); bq_t amc = cw * (A - 1.0f); bq_t bs = b * sw; bq_t a0r = 1.0f / (A + 1.0f - amc + bs); f->b0 = a0r * A * (A + 1.0f + amc + bs); f->b1 = a0r * -2.0f * A * (A - 1.0f + apc); f->b2 = a0r * A * (A + 1.0f + amc - bs); f->a1 = a0r * -2.0f * (A - 1.0f - apc); f->a2 = a0r * (-A - 1.0f + amc + bs); } static inline bq_t biquad_run(biquad *f, bq_t x) { union { bq_t y; uint32_t y_int; } u; u.y = f->b0 * x + f->b1 * f->x1 + f->b2 * f->x2 + f->a1 * f->y1 + f->a2 * f->y2; if ((u.y_int & 0x7f800000) == 0) u.y = 0.0f; f->x2 = f->x1; f->x1 = x; f->y2 = f->y1; f->y1 = u.y; return u.y; }