ref: 6f9a028cad836b8f41f479d244be849fc16e48b8
dir: /src_common/SKP_Silk_pulses_to_bytes.c/
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/*
* File Name: SKP_Silk_pulses_to_bytes.c
*/
#include <stdlib.h>
#include "SKP_Silk_main.h"
/* nBytes = sum_over_shell_blocks( POLY_FIT_0 + POLY_FIT_1 * sum_abs_val + POLY_FIT_2 * sum_abs_val^2 ) */
#define POLY_FIT_0_Q15 12520
#define POLY_FIT_1_Q15 15862
#define POLY_FIT_2_Q20 -9222
/* Predict number of bytes used to encode q */
SKP_int SKP_Silk_pulses_to_bytes( /* O Return value, predicted number of bytes used to encode q */
SKP_Silk_encoder_state *psEncC, /* I/O Encoder State */
SKP_int8 q[] /* I Pulse signal */
)
{
SKP_int i, j, iter;
SKP_int8 *q_ptr;
SKP_int32 sum_abs_val, nBytes, acc_nBytes;
/* Take the absolute value of the pulses */
iter = psEncC->frame_length / SHELL_CODEC_FRAME_LENGTH;
/* Calculate rate as a nonlinaer mapping of sum abs value of each Shell block */
q_ptr = q;
acc_nBytes = 0;
for( j = 0; j < iter; j++ ) {
sum_abs_val = 0;
for(i = 0; i < SHELL_CODEC_FRAME_LENGTH; i+=4){
sum_abs_val += (SKP_int32)SKP_abs( q_ptr[ i + 0 ] );
sum_abs_val += (SKP_int32)SKP_abs( q_ptr[ i + 1 ] );
sum_abs_val += (SKP_int32)SKP_abs( q_ptr[ i + 2 ] );
sum_abs_val += (SKP_int32)SKP_abs( q_ptr[ i + 3 ] );
}
/* Calculate nBytes used for thi sshell frame */
nBytes = SKP_SMULWB( SKP_SMULBB( sum_abs_val, sum_abs_val ), POLY_FIT_2_Q20 ); // Q4
nBytes = SKP_LSHIFT_SAT32( nBytes, 11 ); // Q15
nBytes += SKP_SMULBB( sum_abs_val, POLY_FIT_1_Q15 ); // Q15
nBytes += POLY_FIT_0_Q15; // Q15
#ifdef SAVE_ALL_INTERNAL_DATA
DEBUG_STORE_DATA( sum_abs_val.dat, &sum_abs_val, sizeof( SKP_int32 ) );
#endif
acc_nBytes += nBytes;
q_ptr += SHELL_CODEC_FRAME_LENGTH; /* update pointer */
}
acc_nBytes = SKP_RSHIFT_ROUND( acc_nBytes, 15 ); // Q0
acc_nBytes = SKP_SAT16( acc_nBytes ); // just to be sure // Q0
return(( SKP_int )acc_nBytes);
}