From b39cd568e3b10f7fa3188bf35ff7f95521ceb0e8 Mon Sep 17 00:00:00 2001 From: Shriram Shastry Date: Thu, 23 May 2024 12:24:59 +0530 Subject: [PATCH] Audio: Optimize division by speed of sound using fixed-point reciprocal This commit optimizes the division by the speed of sound in the `theoretical_time_differences` function. By precomputing the fixed-point reciprocal of the speed of sound, we eliminate the need for a costly division operation in each iteration. Additionally, a redundant 'if' statement is removed from the 'tdfb_direction_copy_emphasis' function, simplifying the code. Signed-off-by: Shriram Shastry --- src/audio/tdfb/tdfb_direction.c | 8 ++++---- src/include/sof/math/numbers.h | 1 + 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/src/audio/tdfb/tdfb_direction.c b/src/audio/tdfb/tdfb_direction.c index bbf9c9be1de1..a3282b5ccdf4 100644 --- a/src/audio/tdfb/tdfb_direction.c +++ b/src/audio/tdfb/tdfb_direction.c @@ -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++; @@ -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); } } diff --git a/src/include/sof/math/numbers.h b/src/include/sof/math/numbers.h index 1fd61f6324eb..0cd9314f4859 100644 --- a/src/include/sof/math/numbers.h +++ b/src/include/sof/math/numbers.h @@ -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__ */