px4-firmware/nuttx/libc/Kconfig

#
# For a description of the syntax of this configuration file,
# see misc/tools/kconfig-language.txt.
#

comment "Standard C Library Options"

config STDIO_BUFFER_SIZE
	int "C STDIO buffer size"
	default 64
	---help---
		Size of buffers using within the C buffered I/O interfaces.
		(printf, putchar, fwrite, etc.).

config STDIO_LINEBUFFER
	bool "STDIO line buffering"
	default y
	---help---
		Flush buffer I/O whenever a newline character is found in
		the output data stream.

config NUNGET_CHARS
	int "Number unget() characters"
	default 2
	---help---
		Number of characters that can be buffered by ungetc() (Only if NFILE_STREAMS > 0)

config LIB_HOMEDIR
	string "Home directory"
	default "/"
	depends on !DISABLE_ENVIRON
	---help---
		The home directory to use with operations like such as 'cd ~'

source libc/math/Kconfig

config NOPRINTF_FIELDWIDTH
	bool "Disable sprintf support fieldwidth"
	default n
	---help---
	sprintf-related logic is a
	little smaller if we do not support fieldwidthes

config LIBC_FLOATINGPOINT
	bool "Enable floating point in printf"
	default n
	---help---
		By default, floating point
		support in printf, sscanf, etc. is disabled.

choice
	prompt "Newline Options"
	default EOL_IS_EITHER_CRLF
	---help---
		This selection determines the line terminating character that is used.
		Some environments may return CR as end-of-line, others LF, and others
		both.  If not specified, the default is either CR or LF (but not both)
		as the line terminating charactor.

config EOL_IS_CR
	bool "EOL is CR"

config EOL_IS_LF
	bool "EOL is LF"

config EOL_IS_BOTH_CRLF
	bool "EOL is CR and LF"

config EOL_IS_EITHER_CRLF
	bool "EOL is CR or LF"

endchoice

config LIBC_EXECFUNCS
	bool "Enable exec[l|v] / posix_spawn() Support"
	default n
	depends on !BINFMT_DISABLE
	---help---
		Enable support for the exec[l|v] family of functions that can be
		used to start other programs, terminating the current program and
		the posix_spawn() familty of functions that can be used start other
		programs without terminating the current program.  The typical
		usage of the exec[l|v] functions is (1) first call vfork() to create
		a new thread, then (2) call exec[l|v] to replace the new thread with
		a program from the file system.

		NOTE 1: This two step process start is completely unnecessary in
		NuttX and is provided only for compatibily with Unix systems.  These
		functions are essentially just wrapper functions that (1) call the
		non-standard binfmt function 'exec', and then (2) exit(0).  Since
		the new thread will be terminated by the exec[l|v] call, it really
		served no purpose other than to suport Unix compatility.

		The posix_spawn() functions do not have this inefficiency.

		NOTE 2: Support for exec[l|v] and posix_spawn() is conditional
		because they require additional support for symbol tables that
		will not be available in the typical system.

if LIBC_EXECFUNCS

config EXECFUNCS_SYMTAB
	string "Symbol table used by exec[l|v]"
	default "g_symtab"
	---help---
		The exec[l|v] and posix_spawn() functions are wrapper functions that
		call the non-standard binfmt function 'exec').  The binfmt
		function 'exec' needs to have (1) a symbol table that provides the
		list of symbols exported by the base code, and (2) the number of
		symbols in that table.  This selection provides the name of that
		symbol table.

config EXECFUNCS_NSYMBOLS
	int "Number of Symbols in the Table"
	default 0
	---help---
		The exec[l|v] and posix_spawn() functions are wrapper functions that
		call the non-standard binfmt function 'exec').  The binfmt
		function 'exec' needs to have (1) a symbol table that provides the
		list of symbols exported by the base code, and (2) the number of
		symbols in that table.  This selection provides the number of
		symbols in the symbol table.

config POSIX_SPAWN_STACKSIZE
	int "posix_spawn Stack Size"
	default 1024
	---help---
		If posix_spawn[p] uses I/O redirection options, then it will require
		an intermediary/proxy task to muck with the file descriptors.  This
		configuration item specifies the stack size used for the proxy. Default:
		1024 bytes.

endif

config LIBC_STRERROR
	bool "Enable strerror"
	default n
	---help---
		strerror() is useful because it decodes 'errno' values into a human readable
		strings.  But it can also require a lot of memory.  If this option is selected,
		strerror() will still exist in the build but it will not decode error values.
		This option should be used by other logic to decide if it should use strerror()
		or not.  For example, the NSH application will not use strerror() if this
		option is not selected; perror() will not use strerror() is this option is not
		selected (see also NSH_STRERROR).

config LIBC_STRERROR_SHORT
	bool "Use short error descriptions in strerror()"
	default n
	depends on LIBC_STRERROR
	---help---
		If this option is selected, then strerror() will use a shortened string when
		it decodes the error.  Specifically, strerror() is simply use the string that
		is the common name for the error.  For example, the 'errno' value of 2 will
		produce the string "No such file or directory" is LIBC_STRERROR_SHORT
		is not defined but the string "ENOENT" is LIBC_STRERROR_SHORT is defined.

config LIBC_PERROR_STDOUT
	bool "perror() to stdout"
	default n
	---help---
		POSIX requires that perror() provide its output on stderr.  This option may
		be defined, however, to provide perror() output that is serialized with
		other stdout messages.

config ARCH_LOWPUTC
	bool "Low-level console output"
	default "y"
	---help---
		architecture supports low-level, boot time console output

config LIB_SENDFILE_BUFSIZE
	int "sendfile() buffer size"
	default 512
	---help---
		Size of the I/O buffer to allocate in sendfile().  Default: 512b

config ARCH_ROMGETC
	bool "Support for ROM string access"
	default n
	---help---
		In Harvard architectures, data accesses and instruction accesses
		occur on different busses, perhaps concurrently.  All data accesses
		are performed on the data bus unless special machine instructions
		are used to read data from the instruction address space.  Also, in
		the typical MCU, the available SRAM data memory is much smaller that
		the non-volatile FLASH instruction memory.  So if the application
		requires many constant strings, the only practical solution may be
		to store those constant strings in FLASH memory where they can only
		be accessed using architecture-specific machine instructions.

		If ARCH_ROMGETC is defined, then the architecture logic must export
		the function up_romgetc().  up_romgetc() will simply read one byte
		of data from the instruction space.

		If ARCH_ROMGETC, certain C stdio functions are effected: (1) All
		format strings in printf, fprintf, sprintf, etc. are assumed to lie
		in FLASH (string arguments for %s are still assumed to reside in SRAM).
		And (2), the string argument to puts and fputs is assumed to reside
		in FLASH.  Clearly, these assumptions may have to modified for the
		particular needs of your environment.  There is no "one-size-fits-all"
		solution for this problem.

config ARCH_OPTIMIZED_FUNCTIONS
	bool "Enable arch optimized functions"
	default n
	---help---
		Allow for architecture optimized implementations of certain library
		functions.  Architecture-specific implementations can improve overall
		system performance.

if ARCH_OPTIMIZED_FUNCTIONS
config ARCH_MEMCPY
	bool "memcpy()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of memcpy().

config MEMCPY_VIK
	bool "Vik memcpy()"
	default n
	depends on !ARCH_MEMCPY
	---help---
		Select this option to use the optimized memcpy() function by Daniel Vik.
		Select this option for improved performance at the expense of increased
		size. See licensing information in the top-level COPYING file.

if MEMCPY_VIK
config MEMCPY_PRE_INC_PTRS
	bool "Pre-increment pointers"
	default n
	---help---
		Use pre-increment of pointers. Default is post increment of pointers.

config MEMCPY_INDEXED_COPY
	bool "Array indexing"
	default y
	---help---
		Copying data using array indexing. Using this option, disables the
		MEMCPY_PRE_INC_PTRS option.

config MEMCPY_64BIT
	bool "64-bit memcpy()"
	default n
	---help---
		Compiles memcpy() for architectures that suppport 64-bit operations
		efficiently.

endif

config ARCH_MEMCMP
	bool "memcmp()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of memcmp().

config ARCH_MEMMOVE
	bool "memmove()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of memmove().

config ARCH_MEMSET
	bool "memset()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of memset().

config MEMSET_OPTSPEED
	bool "Optimize memset() for speed"
	default n
	depends on !ARCH_MEMSET
	---help---
		Select this option to use a version of memcpy() optimized for speed.
		Default: memcpy() is optimized for size.

config MEMSET_64BIT
	bool "64-bit memset()"
	default n
	depends on MEMSET_OPTSPEED
	---help---
		Compiles memset() for architectures that suppport 64-bit operations
		efficiently.

config ARCH_STRCHR
	bool "strchr()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strchr().

config ARCH_STRCMP
	bool "strcmp()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strcmp().

config ARCH_STRCPY
	bool "strcpy()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strcpy().

config ARCH_STRNCPY
	bool "strncpy()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strncpy().

config ARCH_STRLEN
	bool "strlen"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strlen().

config ARCH_STRNLEN
	bool "strlen()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of strnlen().

config ARCH_BZERO
	bool "bzero()"
	default n
	---help---
		Select this option if the architecture provides an optimized version
		of bzero().

endif

comment "Non-standard Helper Functions"

config LIB_KBDCODEC
	bool "Keyboard CODEC"
	default n
	---help---
		In NuttX, a keyboard/keypad driver is simply a character driver that
		may have an (optional) encoding/decoding layer on the data returned
		by the character driver. A keyboard may return simple text data
		(alphabetic, numeric, and punctuaction) or control characters
		(enter, control-C, etc.).  We can think about this the normal
		"in-band" keyboard data stream.  However, in addition, most
		keyboards support actions that cannot be represented as text data.
		Such actions include things like cursor controls (home, up arrow,
		page down, etc.), editing functions (insert, delete, etc.), volume
		controls, (mute, volume up, etc.) and other special functions.  We
		can think about this as special, "out-of-band" keyboard commands.
		In this case, some special encoding may be required to multiplex
		the in-band text data and out-of-band command streams.

		This option enables the functions that implement the encoding and
		decoding of keyboard data.  These are the interfaces prototyped in
		include/nuttx/input/kbd_codec.h.  While not correctly a part of
		the C library, it is included here because the decoding side of this
		interface must be accessible by end user programs.