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Added blancmange curve.

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This commit is contained in:
Ian Abbott 2007-11-30 18:20:15 +00:00
parent 92eb0d52bc
commit 3464515b7d
1 changed files with 25 additions and 5 deletions
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30
demo/ao_waveform.c
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@ -76,6 +76,7 @@ void dds_init_ramp_up(void);
void dds_init_ramp_down(void);
void dds_init_triangle(void);
void dds_init_square(void);
void dds_init_blancmange(void);
static void (* const dds_init_function[])(void) = {
dds_init_sine,
@ -84,6 +85,7 @@ static void (* const dds_init_function[])(void) = {
dds_init_triangle,
dds_init_square,
dds_init_cycloid,
dds_init_blancmange,
};
#define NUMFUNCS (sizeof(dds_init_function)/sizeof(dds_init_function[0]))
@ -245,6 +247,11 @@ void dds_output(sampl_t *buf,int n)
}
}
/* Defined for x in [0,1] */
static inline double triangle(double x)
{
return (x > 0.5) ? 1.0 - x : x;
}
void dds_init_sine(void)
{
@ -319,11 +326,8 @@ void dds_init_triangle(void)
{
int i;
for (i = 0; i <= WAVEFORM_LEN / 2; i++) {
waveform[i] = rint(offset + amplitude * (i * 2) / WAVEFORM_LEN);
}
for ( ; i < WAVEFORM_LEN; i++) {
waveform[i] = rint(offset + amplitude * ((WAVEFORM_LEN - i) * 2) / WAVEFORM_LEN);
for (i = 0; i < WAVEFORM_LEN; i++) {
waveform[i] = rint(offset + amplitude * 2 * triangle((double)i / WAVEFORM_LEN));
}
}
@ -339,3 +343,19 @@ void dds_init_square(void)
}
}
void dds_init_blancmange(void)
{
int i, n;
double b, x;
for (i = 0; i < WAVEFORM_LEN; i++) {
b = 0;
for (n = 0; n < 16; n++) {
x = (double)i / WAVEFORM_LEN;
x *= (1 << n);
x -= floor(x);
b += triangle(x) / (1 << n);
}
waveform[i] = rint(offset + amplitude * 1.5 * b);
}
}