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Diffstat (limited to 'media/libeffects/testlibs/EffectsMath.c')
-rw-r--r-- | media/libeffects/testlibs/EffectsMath.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/media/libeffects/testlibs/EffectsMath.c b/media/libeffects/testlibs/EffectsMath.c new file mode 100644 index 0000000..41ec662 --- /dev/null +++ b/media/libeffects/testlibs/EffectsMath.c @@ -0,0 +1,143 @@ +/* + * Copyright (C) 2008 The Android Open Source Project + * + * 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. + */ +#define LOG_TAG "EFFECTSMATH" +//#define LOG_NDEBUG 0 +#include <cutils/log.h> +#include <assert.h> + +#include "EffectsMath.h" + +// gLogTab contains pre-calculated values of log2(1 + ai5*2^-1 + ai4*2^-2 + ai3*2^-3 + ai2*2^-4 + ai1*2^-5 + ai0*2^-6) +// for integers in the range 0 to 63 (i = ai5*2^5 + ai4*2^4 + ai3*2^3 + ai2*2^2 + ai1*2^1 + ai0*2^0) +// It is used for a better than piece wise approximation of lin to log2 conversion + +static const uint16_t gLogTab[] = +{ + 0, 733, 1455, 2166, + 2866, 3556, 4236, 4907, + 5568, 6220, 6863, 7498, + 8124, 8742, 9352, 9954, + 10549, 11136, 11716, 12289, + 12855, 13415, 13968, 14514, + 15055, 15589, 16117, 16639, + 17156, 17667, 18173, 18673, + 19168, 19658, 20143, 20623, + 21098, 21568, 22034, 22495, + 22952, 23404, 23852, 24296, + 24736, 25172, 25604, 26031, + 26455, 26876, 27292, 27705, + 28114, 28520, 28922, 29321, + 29717, 30109, 30498, 30884, + 31267, 31647, 32024, 32397, + 32768 +}; + +int32_t Effects_log2(uint32_t x) { + int32_t exp = 31 - __builtin_clz(x); + uint32_t segStart = x >> (exp - 6); + uint32_t i = segStart & 0x3F; + int32_t log = (int32_t)gLogTab[i]; + int32_t logEnd = (int32_t)gLogTab[i+1]; + segStart <<= exp - 6; + + return (exp << 15) + log + (((x - segStart) * (logEnd - log)) >> (exp - 6)); +} + +// gExpTab[i] = (2^(i>>6)) << 22 +static const uint32_t gExpTab[] = { + 4194304, 4239977, 4286147, 4332820, + 4380002, 4427697, 4475911, 4524651, + 4573921, 4623728, 4674077, 4724974, + 4776426, 4828438, 4881016, 4934167, + 4987896, 5042211, 5097117, 5152621, + 5208729, 5265449, 5322786, 5380747, + 5439339, 5498570, 5558445, 5618973, + 5680159, 5742012, 5804539, 5867746, + 5931642, 5996233, 6061528, 6127533, + 6194258, 6261709, 6329894, 6398822, + 6468501, 6538938, 6610143, 6682122, + 6754886, 6828442, 6902799, 6977965, + 7053950, 7130763, 7208412, 7286906, + 7366255, 7446469, 7527555, 7609525, + 7692387, 7776152, 7860829, 7946428, + 8032959, 8120432, 8208857, 8298246, + 8388608 +}; + + +uint32_t Effects_exp2(int32_t x) { + int32_t i = x >> 15; + assert(i < 32); + x &= (1 << 15) - 1; + int32_t j = x >> 9; + x &= (1 << 9) - 1; + uint32_t exp = gExpTab[j]; + uint32_t expEnd = gExpTab[j+1]; + + return ((exp << 9) + (expEnd - exp) * x) >> (31 - i); +} + + +int16_t Effects_MillibelsToLinear16 (int32_t nGain) +{ + nGain = ((nGain + MB_TO_LIN_K1) << 15 ) / MB_TO_LIN_K2; + uint32_t exp2 = Effects_exp2(nGain); + + if (exp2 > 32767) exp2 = 32767; + + return (int16_t)exp2; +} + + +int16_t Effects_Linear16ToMillibels (int32_t nGain) +{ + return (int16_t)(((MB_TO_LIN_K2*Effects_log2(nGain))>>15)-MB_TO_LIN_K1); +} + + +int32_t Effects_Sqrt(int32_t in) +{ + int32_t tmp; + int32_t out = 0; + int32_t i; + int32_t j; + + + if (in == 0) return 0; + + if (in >= 0x10000000) + { + out = 0x4000; + in -= 0x10000000; + } + + j = 32 - __builtin_clz(in); + + if (j & 1) j++; + j >>= 1; + + for (i = j; i > 0; i--) { + tmp = (out << i) + (1 << ((i - 1)*2)); + if (in >= tmp) + { + out += 1 << (i-1); + in -= tmp; + } + } + + return out; +} + |