You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
81 lines
2.0 KiB
81 lines
2.0 KiB
7 years ago
|
/*
|
||
|
|
* Copyright 2012 Google Inc.
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
* See the License for the specific language governing permissions and
|
||
|
|
* limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
class Exp2 {
|
||
|
|
public:
|
||
|
|
Exp2();
|
||
|
|
|
||
|
|
static void init();
|
||
|
|
|
||
|
|
// Q24 in, Q24 out
|
||
|
|
static int32_t lookup(int32_t x);
|
||
|
|
};
|
||
|
|
|
||
|
|
#define EXP2_LG_N_SAMPLES 10
|
||
|
|
#define EXP2_N_SAMPLES (1 << EXP2_LG_N_SAMPLES)
|
||
|
|
|
||
|
|
#define EXP2_INLINE
|
||
|
|
|
||
|
|
extern int32_t exp2tab[EXP2_N_SAMPLES << 1];
|
||
|
|
|
||
|
|
#ifdef EXP2_INLINE
|
||
|
|
inline
|
||
|
|
int32_t Exp2::lookup(int32_t x) {
|
||
|
|
const int SHIFT = 24 - EXP2_LG_N_SAMPLES;
|
||
|
|
int lowbits = x & ((1 << SHIFT) - 1);
|
||
|
|
int x_int = (x >> (SHIFT - 1)) & ((EXP2_N_SAMPLES - 1) << 1);
|
||
|
|
int dy = exp2tab[x_int];
|
||
|
|
int y0 = exp2tab[x_int + 1];
|
||
|
|
|
||
|
|
int y = y0 + (((int64_t)dy * (int64_t)lowbits) >> SHIFT);
|
||
|
|
return y >> (6 - (x >> 24));
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
class Tanh {
|
||
|
|
public:
|
||
|
|
static void init();
|
||
|
|
|
||
|
|
// Q24 in, Q24 out
|
||
|
|
static int32_t lookup(int32_t x);
|
||
|
|
};
|
||
|
|
|
||
|
|
#define TANH_LG_N_SAMPLES 10
|
||
|
|
#define TANH_N_SAMPLES (1 << TANH_LG_N_SAMPLES)
|
||
|
|
|
||
|
|
extern int32_t tanhtab[TANH_N_SAMPLES << 1];
|
||
|
|
|
||
|
|
inline
|
||
|
|
int32_t Tanh::lookup(int32_t x) {
|
||
|
|
int32_t signum = x >> 31;
|
||
|
|
x ^= signum;
|
||
|
|
if (x >= (4 << 24)) {
|
||
|
|
if (x >= (17 << 23)) {
|
||
|
|
return signum ^ (1 << 24);
|
||
|
|
}
|
||
|
|
int32_t sx = ((int64_t)-48408812 * (int64_t)x) >> 24;
|
||
|
|
return signum ^ ((1 << 24) - 2 * Exp2::lookup(sx));
|
||
|
|
} else {
|
||
|
|
const int SHIFT = 26 - TANH_LG_N_SAMPLES;
|
||
|
|
int lowbits = x & ((1 << SHIFT) - 1);
|
||
|
|
int x_int = (x >> (SHIFT - 1)) & ((TANH_N_SAMPLES - 1) << 1);
|
||
|
|
int dy = tanhtab[x_int];
|
||
|
|
int y0 = tanhtab[x_int + 1];
|
||
|
|
int y = y0 + (((int64_t)dy * (int64_t)lowbits) >> SHIFT);
|
||
|
|
return y ^ signum;
|
||
|
|
}
|
||
|
|
}
|