PageRenderTime 72ms CodeModel.GetById 48ms app.highlight 20ms RepoModel.GetById 1ms app.codeStats 0ms

/media/libstagefright/codecs/amrwbenc/src/oper_32b.c

https://bitbucket.org/patrikryd/base
C | 223 lines | 48 code | 25 blank | 150 comment | 0 complexity | 1337f8555f0b18eada3602044f904954 MD5 | raw file
Possible License(s): CC0-1.0
  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
 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
 85Word32 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
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
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
195Word32 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