zephyr/lib/os/Kconfig.cbprintf

# Copyright (c) 2020 Nordic Semiconductor ASA
# SPDX-License-Identifier: Apache-2.0

choice CBPRINTF_IMPLEMENTATION
	prompt "Capabilities of cbprintf implementation"
	default CBPRINTF_COMPLETE

config CBPRINTF_COMPLETE
	bool "All selected features"
	help
	  Select this for an implementation that supports all potential
	  conversions, with Kconfig options to control availability at build
	  time.

# 80: -53% / 982 B (80 / 00)
config CBPRINTF_NANO
	bool "Space-optimized but feature-limited"
	# nano needs to count characters if it's the formatter for libc
	imply CBPRINTF_LIBC_SUBSTS if MINIMAL_LIBC
	help
	  If selected a completely different implementation of the core
	  formatting capability is substituted.  This has a much smaller code
	  footprint, but provides fewer capabilities.

endchoice # CBPRINTF_IMPLEMENTATION

choice CBPRINTF_INTEGRAL_CONV
	prompt "Control range of convertible integer values"
	default CBPRINTF_FULL_INTEGRAL

# 01: 0% / 0 B (01 / 00)
config CBPRINTF_FULL_INTEGRAL
	bool "Convert the full range of integer values"
	select PICOLIBC_IO_LONG_LONG if PICOLIBC
	help
	  Build cbprintf with buffers sized to support converting the full
	  range of all integral and pointer values.

	  Selecting this may increase code size on 32-bit systems as
	  GCC's __udivdi3 helper could end up being pulled into the
	  final binary. In any case, this will increase call stack size
	  by a few words.

# 00:
config CBPRINTF_REDUCED_INTEGRAL
	bool "Convert only integer values that fit in 32 bits"
	help
	  Build cbprintf with buffers sized to support converting integer
	  values with no more than 32 bits.

	  This will decrease stack space, but affects conversion of any type
	  with more than 32 bits.  This includes not only intmax_t but any
	  type that can be converted to an integral representation including
	  size_t and pointers.

	  With CBPRINTF_COMPLETE conversions that may result in value-specific
	  truncation are not supported, and the generated text will be the
	  specification (e.g. %jd).

	  With CBPRINTF_NANO all conversions will be attempted but values that
	  cannot fit will be silently truncated.

endchoice

# 02: 82% / 1530 B (02 / 00)
config CBPRINTF_FP_SUPPORT
	bool "Floating point formatting in cbprintf"
	default y if FPU
	depends on CBPRINTF_COMPLETE
	select PICOLIBC_IO_FLOAT if PICOLIBC
	help
	  Build the cbprintf utility function with support for floating
	  point format specifiers.  Selecting this increases stack size
	  requirements slightly, but increases code size significantly.

# 04: 13% / 456 B (07 / 03)
config CBPRINTF_FP_A_SUPPORT
	bool "Floating point %a conversions"
	depends on CBPRINTF_FULL_INTEGRAL
	select CBPRINTF_FP_SUPPORT
	help
	  The %a hexadecimal format for floating point value conversion was
	  added in C99, but the output is not easily understood so it rarely
	  appears in application code.

	  Selecting this adds support for the conversion, but increases the
	  overall code size related to FP support.

# 40: -15% / -508 B (46 / 06)
config CBPRINTF_FP_ALWAYS_A
	bool "Select %a format for all floating point specifications"
	select CBPRINTF_FP_A_SUPPORT
	help
	  The %a format for floats requires significantly less code than the
	  standard decimal representations (%f, %e, %g).  Selecting this
	  option implicitly uses %a (or %A) for all decimal floating
	  conversions.  The precision of the original specification is
	  ignored.

	  Selecting this decreases code size when FP_SUPPORT is enabled.

# 08: 3% / 60 B (08 / 00)
config CBPRINTF_N_SPECIFIER
	bool "Support %n specifications"
	depends on CBPRINTF_COMPLETE
	default y
	help
	  If selected %n can be used to determine the number of characters
	  emitted.  If enabled there is a small increase in code size.

# 180: 18% / 138 B (180 / 80) [NANO]
config CBPRINTF_LIBC_SUBSTS
	bool "Generate C-library compatible functions using cbprintf"
	help
	  If selected wrappers are generated for various C library functions
	  using the cbprintf formatter underneath.  The wrappers use the C
	  library function name with a cb suffix; e.g. printfcb() or
	  vsnprintfcb().

	  When used with CBPRINTF_NANO this increases the implementation code
	  size by a small amount.

module = CBPRINTF_PACKAGE
module-str = cbprintf_package
source "subsys/logging/Kconfig.template.log_config"

config CBPRINTF_PACKAGE_LONGDOUBLE
	bool "Support packaging of long doubles"
	help
	  Option impact required alignment for buffers used for packaging
	  (CBPRINTF_PACKAGE_ALIGNMENT). On most platforms long doubles
	  requires buffer to be 16 bytes aligned. Long doubles are rarely used
	  so such alignment is an unnecessary waste. If option is disabled,
	  then compilation fails if long double is used.

config CBPRINTF_STATIC_PACKAGE_CHECK_ALIGNMENT
	bool "Validate alignment of a static package buffer"
	# To avoid self referential macro when printk is redirected to logging
	depends on !LOG_PRINTK
	help
	  When enabled, CBPRINTF_STATIC_PACKAGE asserts when buffer is not
	  properly aligned. If macro is widely used then assert may impact
	  memory footprint.

config CBPRINTF_PACKAGE_HEADER_STORE_CREATION_FLAGS
	bool
	help
	  Enable this option to store the flags used to create the package
	  into the package itself.

config CBPRINTF_PACKAGE_SUPPORT_TAGGED_ARGUMENTS
	bool
	depends on !PICOLIBC
	select CBPRINTF_PACKAGE_HEADER_STORE_CREATION_FLAGS
	help
	  Hidden option to support tagged arguments in cbvprint_package().
	  If enabled and cbvprint_package() is called with the corresponding
	  flag, the packaging function no longer looks at the format strings
	  to determine the types of arguments, but instead, each argument is
	  tagged with a type by preceding it with another argument as type
	  (integer).