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      1 // Copyright 2015 Google Inc. All rights reserved.
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //     http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 // Soong is a builder for Android that uses Blueprint to parse Blueprints
     16 // files and Ninja to do the dependency tracking and subprocess management.
     17 // Soong itself is responsible for converting the modules read by Blueprint
     18 // into build rules, which will be written to a build.ninja file by Blueprint.
     19 //
     20 // Android build concepts:
     21 //
     22 // Device
     23 // A device is a piece of hardware that will be running Android.  It may specify
     24 // global settings like architecture, filesystem configuration, initialization
     25 // scripts, and device drivers.  A device may support all variants of a single
     26 // piece of hardware, or multiple devices may be used for different variants.
     27 // A build is never targeted directly at a device, it is always targeted at a
     28 // "product".
     29 //
     30 // Product
     31 // A product is a configuration of a device, often for a specific market or
     32 // use case.  It is sometimes referred to as a "SKU".  A product defines
     33 // global settings like supported languages, supported use cases, preinstalled
     34 // modules, and user-visible behavior choices.  A product selects one and only
     35 // one device.
     36 //
     37 // Module
     38 // A module is a definition of something to be built.  It may be a C library or
     39 // binary, a java library, an Android app, etc.  A module may be built for multiple
     40 // targets, even in a single build, for example host and device, or 32-bit device
     41 // and 64-bit device.
     42 //
     43 // Installed module
     44 // An installed module is one that has been requested by the selected product,
     45 // or a dependency of an installed module.
     46 //
     47 // Target architecture
     48 // The target architecture is the preferred architecture supported by the selected
     49 // device.  It is most commonly 32-bit arm, but may also be 64-bit arm, 32-bit or
     50 // 64-bit x86, or mips.
     51 //
     52 // Secondary architecture
     53 // The secondary architecture specifies the architecture to compile a second copy
     54 // of some modules for devices that support multiple architectures, for example
     55 // 64-bit devices that also support 32-bit binaries.
     56 package soong
     57