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Audio: Optimize division by speed of sound using fixed-point reciprocal #9160

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Merged
lgirdwood merged 1 commit into from
Jun 26, 2024
Merged

Audio: Optimize division by speed of sound using fixed-point reciprocal #9160

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8 changes: 4 additions & 4 deletions src/audio/tdfb/tdfb_direction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -87,9 +87,6 @@ void tdfb_direction_copy_emphasis(struct tdfb_comp_data *cd, int ch_count, int *
{
int32_t y;

if (!cd->direction_updates)
return;

y = iir_df1(&cd->direction.emphasis[*ch], x);
*cd->direction.wp = sat_int16(Q_SHIFT_RND(y, 31, 18)); /* 18 dB boost after high-pass */
cd->direction.wp++;
Expand Down Expand Up @@ -406,8 +403,11 @@ static void theoretical_time_differences(struct tdfb_comp_data *cd, int16_t az)

for (i = 0; i < n_mic - 1; i++) {
delta_d = d[i + 1] - d[0]; /* Meters Q4.12 */
/* Multiply delta_d (Q4.12) by RECIPROCAL_SPEED_OF_SOUND_Q31 (Q1.31) and
* right-shift the result by 12 bits to preserve the Q1.31 format.
*/
cd->direction.timediff_iter[i] =
(int32_t)((((int64_t)delta_d) << 19) / SPEED_OF_SOUND);
Q_MULTS_32X32((int64_t)delta_d, RECIPROCAL_SPEED_OF_SOUND_Q31, 12, 31, 31);
}
}

Expand Down
1 change: 1 addition & 0 deletions src/include/sof/math/numbers.h
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Expand Up @@ -117,5 +117,6 @@ uint32_t crc32(uint32_t base, const void *data, uint32_t bytes);

/* Speed of sound (m/s) in 20 C temperature at standard atmospheric pressure */
#define SPEED_OF_SOUND 343
#define RECIPROCAL_SPEED_OF_SOUND_Q31 6260885 /* Q1.31 */

#endif /* __SOF_MATH_NUMBERS_H__ */