#ML Entity Decoding

#define FIO_ENTITY
#include "fio-stl.h"

Decodes a single Markup Language entity (&name;, &#digits;, &#xhex;) into UTF-8. Handy when you need to unescape one entity at a time, for example while scanning HTML or XML text.

#API Functions

#fio_entity

SFUNC size_t fio_entity(char *dest, const char *src, size_t len);

Decodes the entity starting at src (length len). Writes the UTF-8 result to dest, which must be at least 8 bytes. A NUL terminator is written only if the result is shorter than 8 bytes.

Returns: the number of bytes written (excluding NUL), or 0 if src does not start with a valid entity.

Supported forms:

• Named: &name; — case-insensitive, ~40 common entities such as <, &, ©, —.
• Decimal: &#digits;
• Hex: &#xhex; or &#Xhex;

� is replaced with the Unicode replacement character (U+FFFD). Code points above 0x10FFFF are rejected.

#Example

#define FIO_ENTITY
#include "fio-stl.h"

int main(void) {
  const char *s = "© 2026 😀";
  char buf[8];
  size_t n = fio_entity(buf, s, strlen(s));
  printf("decoded: %.*s\n", (int)n, buf);
  return 0;
}