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biquad: Make use of M_SQRT2 constant

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should be in math.h, use it

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
This commit is contained in:
Peter Meerwald 2015-05-20 16:55:31 +02:00 • committed by Peter Meerwald
parent 07c7295b92
commit 815c67f8d7
1 changed files with 6 additions and 6 deletions
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12
src/pulsecore/filter/biquad.c
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@ -22,6 +22,10 @@
#define M_PI 3.14159265358979323846
#endif
#ifndef M_SQRT2
#define M_SQRT2 1.41421356237309504880
#endif
static void set_coefficient(struct biquad *bq, double b0, double b1, double b2,
double a0, double a1, double a2)
{
@ -44,10 +48,8 @@ static void biquad_lowpass(struct biquad *bq, double cutoff)
set_coefficient(bq, 1, 0, 0, 1, 0, 0);
} else if (cutoff > 0) {
/* Compute biquad coefficients for lowpass filter */
double d = sqrt(2);
double theta = M_PI * cutoff;
double sn = 0.5 * d * sin(theta);
double sn = 0.5 * M_SQRT2 * sin(theta);
double beta = 0.5 * (1 - sn) / (1 + sn);
double gamma = (0.5 + beta) * cos(theta);
double alpha = 0.25 * (0.5 + beta - gamma);
@ -78,10 +80,8 @@ static void biquad_highpass(struct biquad *bq, double cutoff)
set_coefficient(bq, 0, 0, 0, 1, 0, 0);
} else if (cutoff > 0) {
/* Compute biquad coefficients for highpass filter */
double d = sqrt(2);
double theta = M_PI * cutoff;
double sn = 0.5 * d * sin(theta);
double sn = 0.5 * M_SQRT2 * sin(theta);
double beta = 0.5 * (1 - sn) / (1 + sn);
double gamma = (0.5 + beta) * cos(theta);
double alpha = 0.25 * (0.5 + beta + gamma);