memchr.c

#include "prism/internal/memchr.h"
 
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
 
#define TRAILING_BYTE_MINIMUM 0x40
 
const void *
pm_memchr(const void *memory, int character, size_t number, bool encoding_changed, const pm_encoding_t *encoding) {
    if (encoding_changed && encoding->multibyte && character >= TRAILING_BYTE_MINIMUM) {
        const uint8_t *source = (const uint8_t *) memory;
        size_t index = 0;
 
        while (index < number) {
            if (source[index] == character) {
                return (void *) (source + index);
            }
 
            size_t width = encoding->char_width(source + index, (ptrdiff_t) (number - index));
            if (width == 0) {
                return NULL;
            }
 
            index += width;
        }
 
        return NULL;
    } else {
        return memchr(memory, character, number);
    }
}