1 /*
2 ** Copyright 2003-2010, VisualOn, Inc.
3 **
4 ** Licensed under the Apache License, Version 2.0 (the "License");
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
8 ** http://www.apache.org/licenses/LICENSE-2.0
9 **
10 ** Unless required by applicable law or agreed to in writing, software
11 ** distributed under the License is distributed on an "AS IS" BASIS,
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16
17 /*****************************************************************************
18 * This file contains operations in double precision. *
19 * These operations are not standard double precision operations. *
20 * They are used where single precision is not enough but the full 32 bits *
21 * precision is not necessary. For example, the function Div_32() has a *
22 * 24 bits precision which is enough for our purposes. *
23 * *
24 * The double precision numbers use a special representation: *
25 * *
26 * L_32 = hi<<16 + lo<<1 *
27 * *
28 * L_32 is a 32 bit integer. *
29 * hi and lo are 16 bit signed integers. *
30 * As the low part also contains the sign, this allows fast multiplication. *
31 * *
32 * 0x8000 0000 <= L_32 <= 0x7fff fffe. *
33 * *
34 * We will use DPF (Double Precision Format )in this file to specify *
35 * this special format. *
36 *****************************************************************************
37 */
38 #include "typedef.h"
39 #include "basic_op.h"
40 #include "oper_32b.h"
41
42 /*****************************************************************************
43 * *
44 * Function L_Extract() *
45 * *
46 * Extract from a 32 bit integer two 16 bit DPF. *
47 * *
48 * Arguments: *
49 * *
50 * L_32 : 32 bit integer. *
51 * 0x8000 0000 <= L_32 <= 0x7fff ffff. *
52 * hi : b16 to b31 of L_32 *
53 * lo : (L_32 - hi<<16)>>1 *
54 *****************************************************************************
55 */
56
VO_L_Extract(Word32 L_32,Word16 * hi,Word16 * lo)57 __inline void VO_L_Extract (Word32 L_32, Word16 *hi, Word16 *lo)
58 {
59 *hi = (Word16)(L_32 >> 16);
60 *lo = (Word16)((L_32 & 0xffff) >> 1);
61 return;
62 }
63
64 /*****************************************************************************
65 * *
66 * Function L_Comp() *
67 * *
68 * Compose from two 16 bit DPF a 32 bit integer. *
69 * *
70 * L_32 = hi<<16 + lo<<1 *
71 * *
72 * Arguments: *
73 * *
74 * hi msb *
75 * lo lsf (with sign) *
76 * *
77 * Return Value : *
78 * *
79 * 32 bit long signed integer (Word32) whose value falls in the *
80 * range : 0x8000 0000 <= L_32 <= 0x7fff fff0. *
81 * *
82 *****************************************************************************
83 */
84
L_Comp(Word16 hi,Word16 lo)85 Word32 L_Comp (Word16 hi, Word16 lo)
86 {
87 Word32 L_32;
88
89 L_32 = L_deposit_h (hi);
90
91 return (L_mac (L_32, lo, 1)); /* = hi<<16 + lo<<1 */
92 }
93
94 /*****************************************************************************
95 * Function Mpy_32() *
96 * *
97 * Multiply two 32 bit integers (DPF). The result is divided by 2**31 *
98 * *
99 * L_32 = (hi1*hi2)<<1 + ( (hi1*lo2)>>15 + (lo1*hi2)>>15 )<<1 *
100 * *
101 * This operation can also be viewed as the multiplication of two Q31 *
102 * number and the result is also in Q31. *
103 * *
104 * Arguments: *
105 * *
106 * hi1 hi part of first number *
107 * lo1 lo part of first number *
108 * hi2 hi part of second number *
109 * lo2 lo part of second number *
110 * *
111 *****************************************************************************
112 */
113
Mpy_32(Word16 hi1,Word16 lo1,Word16 hi2,Word16 lo2)114 __inline Word32 Mpy_32 (Word16 hi1, Word16 lo1, Word16 hi2, Word16 lo2)
115 {
116 Word32 L_32;
117 L_32 = (hi1 * hi2);
118 L_32 += (hi1 * lo2) >> 15;
119 L_32 += (lo1 * hi2) >> 15;
120 L_32 <<= 1;
121
122 return (L_32);
123 }
124
125 /*****************************************************************************
126 * Function Mpy_32_16() *
127 * *
128 * Multiply a 16 bit integer by a 32 bit (DPF). The result is divided *
129 * by 2**15 *
130 * *
131 * *
132 * L_32 = (hi1*lo2)<<1 + ((lo1*lo2)>>15)<<1 *
133 * *
134 * Arguments: *
135 * *
136 * hi hi part of 32 bit number. *
137 * lo lo part of 32 bit number. *
138 * n 16 bit number. *
139 * *
140 *****************************************************************************
141 */
142
Mpy_32_16(Word16 hi,Word16 lo,Word16 n)143 __inline Word32 Mpy_32_16 (Word16 hi, Word16 lo, Word16 n)
144 {
145 Word32 L_32;
146
147 L_32 = (hi * n)<<1;
148 L_32 += (((lo * n)>>15)<<1);
149
150 return (L_32);
151 }
152
153 /*****************************************************************************
154 * *
155 * Function Name : Div_32 *
156 * *
157 * Purpose : *
158 * Fractional integer division of two 32 bit numbers. *
159 * L_num / L_denom. *
160 * L_num and L_denom must be positive and L_num < L_denom. *
161 * L_denom = denom_hi<<16 + denom_lo<<1 *
162 * denom_hi is a normalize number. *
163 * *
164 * Inputs : *
165 * *
166 * L_num *
167 * 32 bit long signed integer (Word32) whose value falls in the *
168 * range : 0x0000 0000 < L_num < L_denom *
169 * *
170 * L_denom = denom_hi<<16 + denom_lo<<1 (DPF) *
171 * *
172 * denom_hi *
173 * 16 bit positive normalized integer whose value falls in the *
174 * range : 0x4000 < hi < 0x7fff *
175 * denom_lo *
176 * 16 bit positive integer whose value falls in the *
177 * range : 0 < lo < 0x7fff *
178 * *
179 * Return Value : *
180 * *
181 * L_div *
182 * 32 bit long signed integer (Word32) whose value falls in the *
183 * range : 0x0000 0000 <= L_div <= 0x7fff ffff. *
184 * *
185 * Algorithm: *
186 * *
187 * - find = 1/L_denom. *
188 * First approximation: approx = 1 / denom_hi *
189 * 1/L_denom = approx * (2.0 - L_denom * approx ) *
190 * *
191 * - result = L_num * (1/L_denom) *
192 *****************************************************************************
193 */
194
Div_32(Word32 L_num,Word16 denom_hi,Word16 denom_lo)195 Word32 Div_32 (Word32 L_num, Word16 denom_hi, Word16 denom_lo)
196 {
197 Word16 approx, hi, lo, n_hi, n_lo;
198 Word32 L_32;
199
200 /* First approximation: 1 / L_denom = 1/denom_hi */
201
202 approx = div_s ((Word16) 0x3fff, denom_hi);
203
204 /* 1/L_denom = approx * (2.0 - L_denom * approx) */
205
206 L_32 = Mpy_32_16 (denom_hi, denom_lo, approx);
207
208 L_32 = L_sub ((Word32) 0x7fffffffL, L_32);
209 hi = L_32 >> 16;
210 lo = (L_32 & 0xffff) >> 1;
211
212 L_32 = Mpy_32_16 (hi, lo, approx);
213
214 /* L_num * (1/L_denom) */
215 hi = L_32 >> 16;
216 lo = (L_32 & 0xffff) >> 1;
217 VO_L_Extract (L_num, &n_hi, &n_lo);
218 L_32 = Mpy_32 (n_hi, n_lo, hi, lo);
219 L_32 = L_shl2(L_32, 2);
220
221 return (L_32);
222 }
223
224