This patch adds the %m conversion to printf, which prints the
strerror(errno). Explanation of why is below, this patch also updates
the docs, tests, and build system to accomodate this.
The standard for syslog in posix specifies it uses the same format as
printf, but adds %m which prints the error message string for the
current value of errno. For ease of implementation, it's standard
practice for libc implementers to just add %m to printf instead of
creating a separate parser for syslog.
This is an implementation of `ctime` and includes `ctime_r`.
According to documentation, `ctime` and `ctime_r` are defined as the
following:
```c
char *ctime(const time_t *timep);
char *ctime_r(const time_t *restrict timep, char buf[restrict 26]);
```
closes#86567
The `<time.h>` functions `asctime`, `gmtime`, `mktime` and their `_r`
variants are purely computational functions which convert between well
defined time representations and/or strings. There's no reason these
shouldn't be available in bare-metal builds of the library as well as
hosted ones: even if the library has no way to find out the time in
POSIX format, it might still see POSIX-style `time_t` values in input
data (e.g. network protocols) and need to interpret them.
The only obstacle to this was that the `out_of_range()` helper function
set `errno` to `EOVERFLOW`, which fails in a bare-metal build because
the extra POSIX error values aren't defined, including `EOVERFLOW`. So
I've made that assignment conditional on `EOVERFLOW` being defined.
Fixes#85556.
This requires the user to set the upper bounds of the heap by defining
the symbol `__libc_heap_limit`. The heap begins at `_end` and ends
`__libc_heap_limit` bytes afterwards. This prevents a completely unused
heap from requiring any space, and it prevents the heap from being
zeroed at initialization time as part of BSS. It also allows users to
customize the available heap location without recompiling libc.
I'd think this should eventually be replaced with an implemenation based
on a morecore() library. This would allow the same implementation to use
sbrk() on POSIX, `_end` and `__libc_heap_limit` on embedded, and a
buffer in tests. It would also provide better "wilderness" behavior that
tends to decrease heap fragementation (see Wilson et al.)
See #98096
Rather than selecting the errno implementation based on the platform
which doesn't provide the necessary flexibility, make it configurable.
The errno value location is returned by `int *__llvm_libc_errno()` which
is a common design used by other C libraries.
These are not required and without these dependencies, we would wound up
with an unresolved reference to __cxa_finalize, which can be provided by
the vendor making this compatible with baremetal.
This introduces opaque type `struct __llvm_libc_stdin` and a symbol
`__llvm_libc_stdin_read` that's intended to be provided by the vendor.
`__llvm_libc_stdin_read` intentionally has the same signature as
`cookie_read_function_t` so it can be used with `fopencookie` to
represent `stdin` as `FILE *` in the future.
Rather than propgating a compile define, add an explicit cmake flag for
controlling the size. The default for baremetal is 100KB and the default
for others is 1GB.
Note: our baremetal arm configuration compiles this as
`--target=arm-none-eabi`, so this code is built in -marm mode. It could be
smaller with `--target=armv7-none-eabi -mthumb`. The assembler is valid ARMv5,
or THUMB2, but not THUMB(1).
This reverts commit eca988aa4420f33810f9830c80ff9f149b7928ff. The
underlying libc issue was fixed by PR#95576.
The original PR is #95436 , which adds printf, putchar and vprintf in
bareemetal entrypoints
This PR implements a part of WG14 N2653:
- Define C23 char8_t
- Define C11 char16_t
- Define C11 char32_t
Missing goals are:
- The type of UTF-8 character literals is changed from unsigned char to
char8_t. (Since UTF-8 character literals already have type unsigned
char, this is not a semantic change).
- New mbrtoc8() and c8rtomb() functions declared in <uchar.h> enable
conversions between multibyte characters and UTF-8.
- A new ATOMIC_CHAR8_T_LOCK_FREE macro.
- A new atomic_char8_t typedef name.
We compute atan2f(y, x) in 2 stages:
- Fast step: perform computations in double precision , with relative
errors < 2^-50
- Accurate step: if the result from the Fast step fails Ziv's rounding
test, then we perform computations in double-double precision, with
relative errors < 2^-100.
On Ryzen 5900X, worst-case latency is ~ 200 clocks, compared to average
latency ~ 60 clocks, and average reciprocal throughput ~ 20 clocks.
To match the entrypoints and types we need to exclude __atexithandler_t
and __qsortrcompare_t, as well as qsort_r, which is a GNU extension.
This is a reland of llvm/llvm-project#85030.
These types and conversion functions are used in embedded development.
Note that we cannot yet include other entrypoints such as asctime
because `src/time/time_utils.h` unconditionally uses `EOVERFLOW`, which
is only defined in POSIX and not in C standard. This issue is tracked by
#85556.
We expect to eventually provide a complete implementation, but having an
empty definition is necessary to unblock the use of libc++ in embedded
environments.
See #84884 for more details.
Summary:
I've noticed one problem is that the user includes `stdint.h` the
compiler will do `#include_next <stdint.h>` potentially into a
conflicting implementation on systems with multiple headers installed.
The `clang` header is standards compliant and works with `clang` and
`gcc` which are both of our targets, so I simply copied it here. This
has the effect of including `stdint.h` on clang / LLVM libc behaving the
same as `-ffreestanding`.
