1. 根目录:
2. arch
3. x86
4. boot
5. ctype.h

#ifndef BOOT_ISDIGIT_H

#define BOOT_ISDIGIT_H

static inline int isdigit(int ch)
{
	return (ch >= '0') && (ch <= '9');
}

static inline int isxdigit(int ch)
{
	if (isdigit(ch))
		return true;

	if ((ch >= 'a') && (ch <= 'f'))
		return true;

	return (ch >= 'A') && (ch <= 'F');
}

#endif