| --- |
| layout: doc |
| title: "Starboard Module Reference: configuration_constants.h" |
| --- |
| |
| Declares all configuration variables we will need to use at runtime. These |
| variables describe the current platform in detail to allow cobalt to make |
| runtime decisions based on per platform configurations. |
| |
| ## Variables ## |
| |
| ### kSbDefaultMmapThreshold ### |
| |
| Determines the threshold of allocation size that should be done with mmap (if |
| available), rather than allocated within the core heap. |
| |
| ### kSbFileAltSepChar ### |
| |
| The current platform's alternate file path component separator character. This |
| is like SB_FILE_SEP_CHAR, except if your platform supports an alternate |
| character, then you can place that here. For example, on windows machines, the |
| primary separator character is probably '\', but the alternate is '/'. |
| |
| ### kSbFileAltSepString ### |
| |
| The string form of SB_FILE_ALT_SEP_CHAR. |
| |
| ### kSbFileMaxName ### |
| |
| The current platform's maximum length of the name of a single directory entry, |
| not including the absolute path. |
| |
| ### kSbFileMaxOpen ### |
| |
| The current platform's maximum number of files that can be opened at the same |
| time by one process. |
| |
| ### kSbFileMaxPath ### |
| |
| The current platform's maximum length of an absolute path. |
| |
| ### kSbFileSepChar ### |
| |
| The current platform's file path component separator character. This is the |
| character that appears after a directory in a file path. For example, the |
| absolute canonical path of the file "/path/to/a/file.txt" uses '/' as a path |
| component separator character. |
| |
| ### kSbFileSepString ### |
| |
| The string form of SB_FILE_SEP_CHAR. |
| |
| ### kSbHasMediaWebmVp9Support ### |
| |
| Specifies whether this platform has webm/vp9 support. This should be set to non- |
| zero on platforms with webm/vp9 support. |
| |
| ### kSbHasThreadPrioritySupport ### |
| |
| Whether the current platform supports thread priorities. |
| |
| ### kSbMallocAlignment ### |
| |
| Determines the alignment that allocations should have on this platform. |
| |
| ### kSbMaxSystemPathCacheDirectorySize ### |
| |
| The maximum size the cache directory is allowed to use in bytes. |
| |
| ### kSbMaxThreadLocalKeys ### |
| |
| The maximum number of thread local storage keys supported by this platform. This |
| comes from _POSIX_THREAD_KEYS_MAX. The value of PTHREAD_KEYS_MAX is higher, but |
| unit tests show that the implementation doesn't support nearly as many keys. |
| |
| ### kSbMaxThreadNameLength ### |
| |
| The maximum length of the name for a thread, including the NULL-terminator. |
| |
| ### kSbMaxThreads ### |
| |
| Defines the maximum number of simultaneous threads for this platform. Some |
| platforms require sharing thread handles with other kinds of system handles, |
| like mutexes, so we want to keep this manageable. |
| |
| ### kSbMediaMaxAudioBitrateInBitsPerSecond ### |
| |
| The maximum audio bitrate the platform can decode. The following value equals to |
| 5M bytes per seconds which is more than enough for compressed audio. |
| |
| ### kSbMediaMaxVideoBitrateInBitsPerSecond ### |
| |
| The maximum video bitrate the platform can decode. The following value equals to |
| 8M bytes per seconds which is more than enough for compressed video. |
| |
| ### kSbMediaVideoFrameAlignment ### |
| |
| Specifies how video frame buffers must be aligned on this platform. |
| |
| ### kSbMemoryLogPath ### |
| |
| Defines the path where memory debugging logs should be written to. |
| |
| ### kSbMemoryPageSize ### |
| |
| The memory page size, which controls the size of chunks on memory that |
| allocators deal with, and the alignment of those chunks. This doesn't have to be |
| the hardware-defined physical page size, but it should be a multiple of it. |
| |
| ### kSbNetworkReceiveBufferSize ### |
| |
| Specifies the network receive buffer size in bytes, set via |
| SbSocketSetReceiveBufferSize(). |
| |
| Setting this to 0 indicates that SbSocketSetReceiveBufferSize() should not be |
| called. Use this for OSs (such as Linux) where receive buffer auto-tuning is |
| better. |
| |
| On some platforms, this may affect max TCP window size which may dramatically |
| affect throughput in the presence of latency. |
| |
| If your platform does not have a good TCP auto-tuning mechanism, a setting of |
| (128 * 1024) here is recommended. |
| |
| ### kSbPathSepChar ### |
| |
| The current platform's search path component separator character. When |
| specifying an ordered list of absolute paths of directories to search for a |
| given reason, this is the character that appears between entries. For example, |
| the search path of "/etc/search/first:/etc/search/second" uses ':' as a search |
| path component separator character. |
| |
| ### kSbPathSepString ### |
| |
| The string form of SB_PATH_SEP_CHAR. |
| |
| ### kSbPreferredRgbaByteOrder ### |
| |
| Specifies the preferred byte order of color channels in a pixel. Refer to |
| starboard/configuration.h for the possible values. EGL/GLES platforms should |
| generally prefer a byte order of RGBA, regardless of endianness. |
| |
| ### kSbUserMaxSignedIn ### |
| |
| The maximum number of users that can be signed in at the same time. |
