ref: 1a1736526d1421b682418c47801d967f2bdd0a70
dir: /silk/silk_NLSF_VQ.c/
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#include "silk_main.h"
/* Compute quantization errors for an LPC_order element input vector for a VQ codebook */
void silk_NLSF_VQ(
SKP_int32 err_Q26[], /* O Quantization errors [K] */
const SKP_int16 in_Q15[], /* I Input vectors to be quantized [LPC_order] */
const SKP_uint8 pCB_Q8[], /* I Codebook vectors [K*LPC_order] */
const SKP_int K, /* I Number of codebook vectors */
const SKP_int LPC_order /* I Number of LPCs */
)
{
SKP_int i, m;
SKP_int32 diff_Q15, sum_error_Q30, sum_error_Q26;
SKP_assert( LPC_order <= 16 );
SKP_assert( ( LPC_order & 1 ) == 0 );
/* Loop over codebook */
for( i = 0; i < K; i++ ) {
sum_error_Q26 = 0;
for( m = 0; m < LPC_order; m += 2 ) {
/* Compute weighted squared quantization error for index m */
diff_Q15 = SKP_SUB_LSHIFT32( in_Q15[ m ], ( SKP_int32 )*pCB_Q8++, 7 ); // range: [ -32767 : 32767 ]
sum_error_Q30 = SKP_SMULBB( diff_Q15, diff_Q15 );
/* Compute weighted squared quantization error for index m + 1 */
diff_Q15 = SKP_SUB_LSHIFT32( in_Q15[m + 1], ( SKP_int32 )*pCB_Q8++, 7 ); // range: [ -32767 : 32767 ]
sum_error_Q30 = SKP_SMLABB( sum_error_Q30, diff_Q15, diff_Q15 );
sum_error_Q26 = SKP_ADD_RSHIFT32( sum_error_Q26, sum_error_Q30, 4 );
SKP_assert( sum_error_Q26 >= 0 );
SKP_assert( sum_error_Q30 >= 0 );
}
err_Q26[ i ] = sum_error_Q26;
}
}