project documentation

1 files changed, 36 insertions, 0 deletions

diff --git a/doc/cstd.md b/doc/cstd.md
new file mode 100644
index 0000000..63e39cd
--- /dev/null
+++ b/doc/cstd.md
@@ -0,0 +1,36 @@
+A list of missing standard C features:
+
+## ANSI/C89
+  - K&R style function definitions with type declarations: `h(a, b) int a; double b; { ... }`
+
+## C99
+  - Variable-length arrays (VLAs)
+  - Proper `long double` support in platforms with extended floats (currently equivalent to `double`)
+  - `complex` types, `<tgmath.h>` header
+  - digraphs
+  - Universal character names (`\uXXXX`, `\UXXXXXXXX`)
+  - IEEE 754 float support Annex F IEC 60559 (`FLT_EVAL_METHOD`, `FENV_ACCESS` pragma) (not even GCC or Clang care about this)
+
+## C11
+  - `_Alignas`, `max_align_t`
+  - Multithreading support (`_Thread_local`, atomics)
+  - `u8".."` string literals
+
+## C23
+  - Decimal floating-point types (`_Decimal32`, `_Decimal64`, and `_Decimal128`)
+  - Bit-precise integers (`_BitInt`)
+  - `nullptr`, `nullptr_t`
+  - Binary integer constants
+  - `char8_t`
+  - Digit separator '
+  - Attributes (`[[...]]` syntax)
+  - Labels followed by declarations and }
+  - `true` and `false` keywords
+  - `auto` for type inference, `typeof_unqual`, `constexpr`
+  - `unreachable` macro in `<stddef.h>`
+  - checked int arithmetic (`<stdckdint.h>`)
+  - tagged type compatibility [N3037](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3037.pdf)
+  - storage class specifier for compound literals
+  - preprocessor `#embed` directive, `__has_include`, `__has_c_attribute`
+  - Pragmas for float rounding direction (`STDC FENV_ROUND`, `STDC FENV_DEC_ROUND`)
+  - IEEE 754 decimal floats, interchange and extended types. various `<float.h>` macros,...