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simple-tone: fix sin() rounding for S16 shorts 

- fix sine wave rounding for shorts
 - short epsilon == 1
 - clamp shorts to mag <= 1.0
This commit is contained in:
Kamal Mostafa 2012-08-26 12:34:38 -07:00
parent 762a3ea788
commit f8434f3c94
1 changed files with 10 additions and 6 deletions
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16
src/simple-tone-generator.c
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@ -49,10 +49,12 @@ simpleaudio_tone_init( unsigned int new_sin_table_len, float mag )
unsigned int i; unsigned int i;
unsigned short mag_s = 32767.0 * tone_mag + 0.5f; unsigned short mag_s = 32767.0 * tone_mag + 0.5f;
if ( mag_s < 2 ) // "short epsilon" if ( tone_mag > 1.0f ) // clamp to 1.0 to avoid overflow
mag_s = 2; mag_s = 32767;
if ( mag_s < 1 ) // "short epsilon"
mag_s = 1;
for ( i=0; i<sin_table_len; i++ ) for ( i=0; i<sin_table_len; i++ )
sin_table_short[i] = mag_s * sin(M_PI*2.0*(float)i/sin_table_len); sin_table_short[i] = lroundf( mag_s * sin(M_PI*2.0*(float)i/sin_table_len) );
for ( i=0; i<sin_table_len; i++ ) for ( i=0; i<sin_table_len; i++ )
sin_table_float[i] = tone_mag * sinf(M_PI*2.0*(float)i/sin_table_len); sin_table_float[i] = tone_mag * sinf(M_PI*2.0*(float)i/sin_table_len);
@ -141,10 +143,12 @@ simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur)
short_buf[i] = sin_lu_short(SINE_PHASE_TURNS); short_buf[i] = sin_lu_short(SINE_PHASE_TURNS);
} else { } else {
unsigned short mag_s = 32767.0 * tone_mag + 0.5f; unsigned short mag_s = 32767.0 * tone_mag + 0.5f;
if ( mag_s < 2 ) // "short epsilon" if ( tone_mag > 1.0f ) // clamp to 1.0 to avoid overflow
mag_s = 2; mag_s = 32767;
if ( mag_s < 1 ) // "short epsilon"
mag_s = 1;
for ( i=0; i<nsamples_dur; i++ ) for ( i=0; i<nsamples_dur; i++ )
short_buf[i] = mag_s * sinf(SINE_PHASE_RADIANS); short_buf[i] = lroundf( mag_s * sinf(SINE_PHASE_RADIANS) );
} }
break; break;
} }