ref: 8cb54e11ca0663206fec0f9e36c07260f83fdf95
dir: /silk/silk_Inlines.h/
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/*! \file silk_Inlines.h
* \brief silk_Inlines.h defines inline signal processing functions.
*/
#ifndef _SILK_FIX_INLINES_H_
#define _SILK_FIX_INLINES_H_
#ifdef __cplusplus
extern "C"
{
#endif
/* count leading zeros of SKP_int64 */
SKP_INLINE SKP_int32 silk_CLZ64(SKP_int64 in)
{
SKP_int32 in_upper;
in_upper = (SKP_int32)SKP_RSHIFT64(in, 32);
if (in_upper == 0) {
/* Search in the lower 32 bits */
return 32 + silk_CLZ32( (SKP_int32) in );
} else {
/* Search in the upper 32 bits */
return silk_CLZ32( in_upper );
}
}
/* get number of leading zeros and fractional part (the bits right after the leading one */
SKP_INLINE void silk_CLZ_FRAC(SKP_int32 in, /* I: input */
SKP_int32 *lz, /* O: number of leading zeros */
SKP_int32 *frac_Q7) /* O: the 7 bits right after the leading one */
{
SKP_int32 lzeros = silk_CLZ32(in);
* lz = lzeros;
* frac_Q7 = silk_ROR32(in, 24 - lzeros) & 0x7f;
}
/* Approximation of square root */
/* Accuracy: < +/- 10% for output values > 15 */
/* < +/- 2.5% for output values > 120 */
SKP_INLINE SKP_int32 silk_SQRT_APPROX(SKP_int32 x)
{
SKP_int32 y, lz, frac_Q7;
if( x <= 0 ) {
return 0;
}
silk_CLZ_FRAC(x, &lz, &frac_Q7);
if( lz & 1 ) {
y = 32768;
} else {
y = 46214; /* 46214 = sqrt(2) * 32768 */
}
/* get scaling right */
y >>= SKP_RSHIFT(lz, 1);
/* increment using fractional part of input */
y = SKP_SMLAWB(y, y, SKP_SMULBB(213, frac_Q7));
return y;
}
/* Divide two int32 values and return result as int32 in a given Q-domain */
SKP_INLINE SKP_int32 silk_DIV32_varQ( /* O returns a good approximation of "(a32 << Qres) / b32" */
const SKP_int32 a32, /* I numerator (Q0) */
const SKP_int32 b32, /* I denominator (Q0) */
const SKP_int Qres /* I Q-domain of result (>= 0) */
)
{
SKP_int a_headrm, b_headrm, lshift;
SKP_int32 b32_inv, a32_nrm, b32_nrm, result;
SKP_assert( b32 != 0 );
SKP_assert( Qres >= 0 );
/* Compute number of bits head room and normalize inputs */
a_headrm = silk_CLZ32( SKP_abs(a32) ) - 1;
a32_nrm = SKP_LSHIFT(a32, a_headrm); /* Q: a_headrm */
b_headrm = silk_CLZ32( SKP_abs(b32) ) - 1;
b32_nrm = SKP_LSHIFT(b32, b_headrm); /* Q: b_headrm */
/* Inverse of b32, with 14 bits of precision */
b32_inv = SKP_DIV32_16( SKP_int32_MAX >> 2, SKP_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
/* First approximation */
result = SKP_SMULWB(a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
/* Compute residual by subtracting product of denominator and first approximation */
a32_nrm -= SKP_LSHIFT_ovflw( SKP_SMMUL(b32_nrm, result), 3 ); /* Q: a_headrm */
/* Refinement */
result = SKP_SMLAWB(result, a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
/* Convert to Qres domain */
lshift = 29 + a_headrm - b_headrm - Qres;
if( lshift < 0 ) {
return SKP_LSHIFT_SAT32(result, -lshift);
} else {
if( lshift < 32){
return SKP_RSHIFT(result, lshift);
} else {
/* Avoid undefined result */
return 0;
}
}
}
/* Invert int32 value and return result as int32 in a given Q-domain */
SKP_INLINE SKP_int32 silk_INVERSE32_varQ( /* O returns a good approximation of "(1 << Qres) / b32" */
const SKP_int32 b32, /* I denominator (Q0) */
const SKP_int Qres /* I Q-domain of result (> 0) */
)
{
SKP_int b_headrm, lshift;
SKP_int32 b32_inv, b32_nrm, err_Q32, result;
SKP_assert( b32 != 0 );
SKP_assert( Qres > 0 );
/* Compute number of bits head room and normalize input */
b_headrm = silk_CLZ32( SKP_abs(b32) ) - 1;
b32_nrm = SKP_LSHIFT(b32, b_headrm); /* Q: b_headrm */
/* Inverse of b32, with 14 bits of precision */
b32_inv = SKP_DIV32_16( SKP_int32_MAX >> 2, SKP_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
/* First approximation */
result = SKP_LSHIFT(b32_inv, 16); /* Q: 61 - b_headrm */
/* Compute residual by subtracting product of denominator and first approximation from one */
err_Q32 = SKP_LSHIFT_ovflw( -SKP_SMULWB(b32_nrm, b32_inv), 3 ); /* Q32 */
/* Refinement */
result = SKP_SMLAWW(result, err_Q32, b32_inv); /* Q: 61 - b_headrm */
/* Convert to Qres domain */
lshift = 61 - b_headrm - Qres;
if( lshift <= 0 ) {
return SKP_LSHIFT_SAT32(result, -lshift);
} else {
if( lshift < 32){
return SKP_RSHIFT(result, lshift);
}else{
/* Avoid undefined result */
return 0;
}
}
}
#ifdef __cplusplus
}
#endif
#endif //_SILK_FIX_INLINES_H_