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27 :
28 : /*! \file silk_Inlines.h
29 : * \brief silk_Inlines.h defines OPUS_INLINE signal processing functions.
30 : */
31 :
32 : #ifndef SILK_FIX_INLINES_H
33 : #define SILK_FIX_INLINES_H
34 :
35 : #ifdef __cplusplus
36 : extern "C"
37 : {
38 : #endif
39 :
40 : /* count leading zeros of opus_int64 */
41 : static OPUS_INLINE opus_int32 silk_CLZ64( opus_int64 in )
42 : {
43 : opus_int32 in_upper;
44 :
45 : in_upper = (opus_int32)silk_RSHIFT64(in, 32);
46 : if (in_upper == 0) {
47 : /* Search in the lower 32 bits */
48 : return 32 + silk_CLZ32( (opus_int32) in );
49 : } else {
50 : /* Search in the upper 32 bits */
51 : return silk_CLZ32( in_upper );
52 : }
53 : }
54 :
55 : /* get number of leading zeros and fractional part (the bits right after the leading one */
56 0 : static OPUS_INLINE void silk_CLZ_FRAC(
57 : opus_int32 in, /* I input */
58 : opus_int32 *lz, /* O number of leading zeros */
59 : opus_int32 *frac_Q7 /* O the 7 bits right after the leading one */
60 : )
61 : {
62 0 : opus_int32 lzeros = silk_CLZ32(in);
63 :
64 0 : * lz = lzeros;
65 0 : * frac_Q7 = silk_ROR32(in, 24 - lzeros) & 0x7f;
66 0 : }
67 :
68 : /* Approximation of square root */
69 : /* Accuracy: < +/- 10% for output values > 15 */
70 : /* < +/- 2.5% for output values > 120 */
71 0 : static OPUS_INLINE opus_int32 silk_SQRT_APPROX( opus_int32 x )
72 : {
73 : opus_int32 y, lz, frac_Q7;
74 :
75 0 : if( x <= 0 ) {
76 0 : return 0;
77 : }
78 :
79 0 : silk_CLZ_FRAC(x, &lz, &frac_Q7);
80 :
81 0 : if( lz & 1 ) {
82 0 : y = 32768;
83 : } else {
84 0 : y = 46214; /* 46214 = sqrt(2) * 32768 */
85 : }
86 :
87 : /* get scaling right */
88 0 : y >>= silk_RSHIFT(lz, 1);
89 :
90 : /* increment using fractional part of input */
91 0 : y = silk_SMLAWB(y, y, silk_SMULBB(213, frac_Q7));
92 :
93 0 : return y;
94 : }
95 :
96 : /* Divide two int32 values and return result as int32 in a given Q-domain */
97 0 : static OPUS_INLINE opus_int32 silk_DIV32_varQ( /* O returns a good approximation of "(a32 << Qres) / b32" */
98 : const opus_int32 a32, /* I numerator (Q0) */
99 : const opus_int32 b32, /* I denominator (Q0) */
100 : const opus_int Qres /* I Q-domain of result (>= 0) */
101 : )
102 : {
103 : opus_int a_headrm, b_headrm, lshift;
104 : opus_int32 b32_inv, a32_nrm, b32_nrm, result;
105 :
106 0 : silk_assert( b32 != 0 );
107 0 : silk_assert( Qres >= 0 );
108 :
109 : /* Compute number of bits head room and normalize inputs */
110 0 : a_headrm = silk_CLZ32( silk_abs(a32) ) - 1;
111 0 : a32_nrm = silk_LSHIFT(a32, a_headrm); /* Q: a_headrm */
112 0 : b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
113 0 : b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
114 :
115 : /* Inverse of b32, with 14 bits of precision */
116 0 : b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
117 :
118 : /* First approximation */
119 0 : result = silk_SMULWB(a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
120 :
121 : /* Compute residual by subtracting product of denominator and first approximation */
122 : /* It's OK to overflow because the final value of a32_nrm should always be small */
123 0 : a32_nrm = silk_SUB32_ovflw(a32_nrm, silk_LSHIFT_ovflw( silk_SMMUL(b32_nrm, result), 3 )); /* Q: a_headrm */
124 :
125 : /* Refinement */
126 0 : result = silk_SMLAWB(result, a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
127 :
128 : /* Convert to Qres domain */
129 0 : lshift = 29 + a_headrm - b_headrm - Qres;
130 0 : if( lshift < 0 ) {
131 0 : return silk_LSHIFT_SAT32(result, -lshift);
132 : } else {
133 0 : if( lshift < 32){
134 0 : return silk_RSHIFT(result, lshift);
135 : } else {
136 : /* Avoid undefined result */
137 0 : return 0;
138 : }
139 : }
140 : }
141 :
142 : /* Invert int32 value and return result as int32 in a given Q-domain */
143 0 : static OPUS_INLINE opus_int32 silk_INVERSE32_varQ( /* O returns a good approximation of "(1 << Qres) / b32" */
144 : const opus_int32 b32, /* I denominator (Q0) */
145 : const opus_int Qres /* I Q-domain of result (> 0) */
146 : )
147 : {
148 : opus_int b_headrm, lshift;
149 : opus_int32 b32_inv, b32_nrm, err_Q32, result;
150 :
151 0 : silk_assert( b32 != 0 );
152 0 : silk_assert( Qres > 0 );
153 :
154 : /* Compute number of bits head room and normalize input */
155 0 : b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
156 0 : b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
157 :
158 : /* Inverse of b32, with 14 bits of precision */
159 0 : b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
160 :
161 : /* First approximation */
162 0 : result = silk_LSHIFT(b32_inv, 16); /* Q: 61 - b_headrm */
163 :
164 : /* Compute residual by subtracting product of denominator and first approximation from one */
165 0 : err_Q32 = silk_LSHIFT( ((opus_int32)1<<29) - silk_SMULWB(b32_nrm, b32_inv), 3 ); /* Q32 */
166 :
167 : /* Refinement */
168 0 : result = silk_SMLAWW(result, err_Q32, b32_inv); /* Q: 61 - b_headrm */
169 :
170 : /* Convert to Qres domain */
171 0 : lshift = 61 - b_headrm - Qres;
172 0 : if( lshift <= 0 ) {
173 0 : return silk_LSHIFT_SAT32(result, -lshift);
174 : } else {
175 0 : if( lshift < 32){
176 0 : return silk_RSHIFT(result, lshift);
177 : }else{
178 : /* Avoid undefined result */
179 0 : return 0;
180 : }
181 : }
182 : }
183 :
184 : #ifdef __cplusplus
185 : }
186 : #endif
187 :
188 : #endif /* SILK_FIX_INLINES_H */
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