168 lines
4.3 KiB
ReStructuredText
168 lines
4.3 KiB
ReStructuredText
================
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String Functions
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================
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.. include:: check.rst
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---------------
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Source location
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---------------
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- The main source for string functions is located at:
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``libc/src/string``.
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- The source for string conversion functions is located at:
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``libc/src/stdlib`` and
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``libc/src/__support``.
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- The tests are located at:
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``libc/test/src/string``,
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``libc/test/src/stdlib``, and
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``libc/test/src/__support``
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respectively.
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---------------------
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Implementation Status
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---------------------
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Primary memory functions
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========================
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.. TODO(gchatelet): add details about the memory functions.
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============= =========
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Function Name Available
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============= =========
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bzero |check|
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bcmp |check|
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bcopy |check|
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memcpy |check|
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memset |check|
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memcmp |check|
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memmove |check|
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============= =========
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Other Raw Memory Functions
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==========================
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============= =========
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Function Name Available
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============= =========
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memchr |check|
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memrchr |check|
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memccpy |check|
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mempcpy |check|
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============= =========
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String Memory Functions
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=======================
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============= =========
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Function Name Available
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============= =========
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stpcpy |check|
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stpncpy |check|
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strcpy |check|
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strncpy |check|
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strcat |check|
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strncat |check|
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strdup |check|
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strndup |check|
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============= =========
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String Examination Functions
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============================
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============= =========
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Function Name Available
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============= =========
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strlen |check|
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strnlen |check|
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strcmp |check|
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strncmp |check|
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strchr |check|
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strrchr |check|
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strspn |check|
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strcspn |check|
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strpbrk |check|
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strstr |check|
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strtok |check|
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strtok_r |check|
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============= =========
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String Conversion Functions
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============================
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These functions are not in strings.h, but are still primarily string
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functions, and are therefore tracked along with the rest of the string
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functions.
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The String to float functions were implemented using the Eisel-Lemire algorithm
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(read more about the algorithm here: `The Eisel-Lemire ParseNumberF64 Algorithm
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<https://nigeltao.github.io/blog/2020/eisel-lemire.html>`_). This improved
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the performance of string to float and double, and allowed it to complete this
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comprehensive test 15% faster than glibc: `Parse Number FXX Test Data
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<https://github.com/nigeltao/parse-number-fxx-test-data>`_. The test was done
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with LLVM-libc built on 2022-04-14 and Debian GLibc version 2.33-6. The targets
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``libc_str_to_float_comparison_test`` and
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``libc_system_str_to_float_comparison_test`` were built and run on the test data
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10 times each, skipping the first run since it was an outlier.
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============= =========
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Function Name Available
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============= =========
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atof |check|
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atoi |check|
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atol |check|
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atoll |check|
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strtol |check|
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strtoll |check|
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strtoul |check|
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strtoull |check|
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strtof |check|
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strtod |check|
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strtold |check|
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strtoimax |check|
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strtoumax |check|
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============= =========
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String Error Functions
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======================
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============= =========
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Function Name Available
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============= =========
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strerror
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strerror_s
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strerrorlen_s
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============= =========
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Localized String Functions
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==========================
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These functions require locale.h, and will be added when locale support is
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implemented in LLVM-libc.
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============= =========
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Function Name Available
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============= =========
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strcoll
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strxfrm
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============= =========
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---------------------------
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\<name\>_s String Functions
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---------------------------
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Many String functions have an equivalent _s version, which is intended to be
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more secure and safe than the previous standard. These functions add runtime
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error detection and overflow protection. While they can be seen as an
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improvement, adoption remains relatively low among users. In addition, they are
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being considered for removal, see
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`Field Experience With Annex K — Bounds Checking Interfaces
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<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1967.htm>`_. For these reasons,
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there is no ongoing work to implement them.
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