zephyr/lib/os/Kconfig.cbprintf

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# 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
select 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"
help
Build cbprintf with buffers sized to support converting the full
range of all integral and pointer values.
Selecting this has no effect on code size, but 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 represention 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 "Enable floating point formatting in cbprintf"
default y if FPU
depends on CBPRINTF_COMPLETE
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 "Enable 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.