ref: 256c9595d8004c9f414b6e7a3b6936b705c2c6b2
dir: /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 opus_int64 */
static inline opus_int32 silk_CLZ64( opus_int64 in )
{
opus_int32 in_upper;
in_upper = (opus_int32)silk_RSHIFT64(in, 32);
if (in_upper == 0) {
/* Search in the lower 32 bits */
return 32 + silk_CLZ32( (opus_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 */
static inline void silk_CLZ_FRAC(
opus_int32 in, /* I input */
opus_int32 *lz, /* O number of leading zeros */
opus_int32 *frac_Q7 /* O the 7 bits right after the leading one */
)
{
opus_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 */
static inline opus_int32 silk_SQRT_APPROX( opus_int32 x )
{
opus_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 >>= silk_RSHIFT(lz, 1);
/* increment using fractional part of input */
y = silk_SMLAWB(y, y, silk_SMULBB(213, frac_Q7));
return y;
}
/* Divide two int32 values and return result as int32 in a given Q-domain */
static inline opus_int32 silk_DIV32_varQ( /* O returns a good approximation of "(a32 << Qres) / b32" */
const opus_int32 a32, /* I numerator (Q0) */
const opus_int32 b32, /* I denominator (Q0) */
const opus_int Qres /* I Q-domain of result (>= 0) */
)
{
opus_int a_headrm, b_headrm, lshift;
opus_int32 b32_inv, a32_nrm, b32_nrm, result;
silk_assert( b32 != 0 );
silk_assert( Qres >= 0 );
/* Compute number of bits head room and normalize inputs */
a_headrm = silk_CLZ32( silk_abs(a32) ) - 1;
a32_nrm = silk_LSHIFT(a32, a_headrm); /* Q: a_headrm */
b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
/* Inverse of b32, with 14 bits of precision */
b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
/* First approximation */
result = silk_SMULWB(a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
/* Compute residual by subtracting product of denominator and first approximation */
/* It's OK to overflow because the final value of a32_nrm should always be small */
a32_nrm = silk_SUB32_ovflw(a32_nrm, silk_LSHIFT_ovflw( silk_SMMUL(b32_nrm, result), 3 )); /* Q: a_headrm */
/* Refinement */
result = silk_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 silk_LSHIFT_SAT32(result, -lshift);
} else {
if( lshift < 32){
return silk_RSHIFT(result, lshift);
} else {
/* Avoid undefined result */
return 0;
}
}
}
/* Invert int32 value and return result as int32 in a given Q-domain */
static inline opus_int32 silk_INVERSE32_varQ( /* O returns a good approximation of "(1 << Qres) / b32" */
const opus_int32 b32, /* I denominator (Q0) */
const opus_int Qres /* I Q-domain of result (> 0) */
)
{
opus_int b_headrm, lshift;
opus_int32 b32_inv, b32_nrm, err_Q32, result;
silk_assert( b32 != 0 );
silk_assert( Qres > 0 );
/* Compute number of bits head room and normalize input */
b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
/* Inverse of b32, with 14 bits of precision */
b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
/* First approximation */
result = silk_LSHIFT(b32_inv, 16); /* Q: 61 - b_headrm */
/* Compute residual by subtracting product of denominator and first approximation from one */
err_Q32 = silk_LSHIFT( ((opus_int32)1<<29) - silk_SMULWB(b32_nrm, b32_inv), 3 ); /* Q32 */
/* Refinement */
result = silk_SMLAWW(result, err_Q32, b32_inv); /* Q: 61 - b_headrm */
/* Convert to Qres domain */
lshift = 61 - b_headrm - Qres;
if( lshift <= 0 ) {
return silk_LSHIFT_SAT32(result, -lshift);
} else {
if( lshift < 32){
return silk_RSHIFT(result, lshift);
}else{
/* Avoid undefined result */
return 0;
}
}
}
#ifdef __cplusplus
}
#endif
#endif /* SILK_FIX_INLINES_H */