text: #ifndef BUILD_CONFIG_H
  #define BUILD_CONFIG_H
  
  #if defined(__APPLE__)
  // only include TargetConditions after testing ANDROID as some android builds
  // on mac don't have this header available and it's not needed unless the target
  // is really mac/ios.
  #include <TargetConditionals.h>
  #define OS_MACOSX 1
  #if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
  #define OS_IOS 1
  #endif  // defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
  #elif defined(__linux__)
  #define OS_LINUX 1
  // include a system header to pull in features.h for glibc/uclibc macros.
  #include <unistd.h>
  #if defined(__GLIBC__) && !defined(__UCLIBC__)
  // we really are using glibc, not uClibc pretending to be glibc
  #define LIBC_GLIBC 1
  #endif
  #elif defined(_WIN32)
  #define OS_WIN 1
  #elif defined(__Fuchsia__)
  #define OS_FUCHSIA 1
  #elif defined(__FreeBSD__)
  #define OS_FREEBSD 1
  #elif defined(__NetBSD__)
  #define OS_NETBSD 1
  #elif defined(__OpenBSD__)
  #define OS_OPENBSD 1
  #elif defined(__sun)
  #define OS_SOLARIS 1
  #elif defined(__QNXNTO__)
  #define OS_QNX 1
  #elif defined(_AIX)
  #define OS_AIX 1
  #elif defined(__asmjs__) || defined(__wasm__)
  #define OS_ASMJS
  #else
  #error Please add support for your platform in build/build_config.h
  #endif
  // NOTE: Adding a new port? Please follow
  // https://chromium.googlesource.com/chromium/src/+/master/docs/new_port_policy.md
  
  // For access to standard BSD features, use OS_BSD instead of a
  // more specific macro.
  #if defined(OS_FREEBSD) || defined(OS_NETBSD) || defined(OS_OPENBSD)
  #define OS_BSD 1
  #endif
  
  // For access to standard POSIXish features, use OS_POSIX instead of a
  // more specific macro.
  #if defined(OS_AIX) || defined(OS_ANDROID) || defined(OS_ASMJS) ||    \
      defined(OS_FREEBSD) || defined(OS_LINUX) || defined(OS_MACOSX) || \
      defined(OS_NACL) || defined(OS_NETBSD) || defined(OS_OPENBSD) ||  \
      defined(OS_QNX) || defined(OS_SOLARIS)
  #define OS_POSIX 1
  #endif
  
  // Compiler detection. Note: clang masquerades as GCC on POSIX and as MSVC on
  // Windows.
  #if defined(__GNUC__)
  #define COMPILER_GCC 1
  #elif defined(_MSC_VER)
  #define COMPILER_MSVC 1
  #else
  #error Please add support for your compiler in build/build_config.h
  #endif
  
  // Processor architecture detection.  For more info on what's defined, see:
  //   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
  //   http://www.agner.org/optimize/calling_conventions.pdf
  //   or with gcc, run: "echo | gcc -E -dM -"
  #if defined(_M_X64) || defined(__x86_64__)
  #define ARCH_CPU_X86_FAMILY 1
  #define ARCH_CPU_X86_64 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(_M_IX86) || defined(__i386__)
  #define ARCH_CPU_X86_FAMILY 1
  #define ARCH_CPU_X86 1
  #define ARCH_CPU_32_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(__s390x__)
  #define ARCH_CPU_S390_FAMILY 1
  #define ARCH_CPU_S390X 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_BIG_ENDIAN 1
  #elif defined(__s390__)
  #define ARCH_CPU_S390_FAMILY 1
  #define ARCH_CPU_S390 1
  #define ARCH_CPU_31_BITS 1
  #define ARCH_CPU_BIG_ENDIAN 1
  #elif (defined(__PPC64__) || defined(__PPC__)) && defined(__BIG_ENDIAN__)
  #define ARCH_CPU_PPC64_FAMILY 1
  #define ARCH_CPU_PPC64 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_BIG_ENDIAN 1
  #elif defined(__PPC64__)
  #define ARCH_CPU_PPC64_FAMILY 1
  #define ARCH_CPU_PPC64 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(__ARMEL__)
  #define ARCH_CPU_ARM_FAMILY 1
  #define ARCH_CPU_ARMEL 1
  #define ARCH_CPU_32_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(__aarch64__) || defined(_M_ARM64)
  #define ARCH_CPU_ARM_FAMILY 1
  #define ARCH_CPU_ARM64 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(__pnacl__) || defined(__asmjs__) || defined(__wasm__)
  #define ARCH_CPU_32_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #elif defined(__MIPSEL__)
  #if defined(__LP64__)
  #define ARCH_CPU_MIPS_FAMILY 1
  #define ARCH_CPU_MIPS64EL 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #else
  #define ARCH_CPU_MIPS_FAMILY 1
  #define ARCH_CPU_MIPSEL 1
  #define ARCH_CPU_32_BITS 1
  #define ARCH_CPU_LITTLE_ENDIAN 1
  #endif
  #elif defined(__MIPSEB__)
  #if defined(__LP64__)
  #define ARCH_CPU_MIPS_FAMILY 1
  #define ARCH_CPU_MIPS64 1
  #define ARCH_CPU_64_BITS 1
  #define ARCH_CPU_BIG_ENDIAN 1
  #else
  #define ARCH_CPU_MIPS_FAMILY 1
  #define ARCH_CPU_MIPS 1
  #define ARCH_CPU_32_BITS 1
  #define ARCH_CPU_BIG_ENDIAN 1
  #endif
  #else
  #error Please add support for your architecture in build/build_config.h
  #endif
  
  #endif