1 /* 2 * Copyright (C) 2020 The Android Open Source Project 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 #include <stddef.h> 18 #include <stdint.h> 19 DecodeALaw(int16_t * out,const uint8_t * in,size_t inSize)20void DecodeALaw(int16_t *out, const uint8_t *in, size_t inSize) { 21 if (out != nullptr && in != nullptr) { 22 while (inSize > 0) { 23 inSize--; 24 int32_t x = *in++; 25 26 int32_t ix = x ^ 0x55; 27 ix &= 0x7f; 28 29 int32_t iexp = ix >> 4; 30 int32_t mant = ix & 0x0f; 31 32 if (iexp > 0) { 33 mant += 16; 34 } 35 36 mant = (mant << 4) + 8; 37 38 if (iexp > 1) { 39 mant = mant << (iexp - 1); 40 } 41 42 *out++ = (x > 127) ? mant : -mant; 43 } 44 } 45 } 46