LibC: Add is*() functions to libc

libc/Makefile

@@ -31,6 +31,7 @@ BUILDDIR=$(abspath build)
  
 FREEOBJS=\
 $(ARCH_FREEOBJS) \
+ctype.o \
 stdio/printf.o \
 stdio/putchar.o \
 stdio/puts.o \

libc/ctype.cpp

@@ -0,0 +1,66 @@
+#include <ctype.h>
+
+int isalnum(int c)
+{
+	return isdigit(c) || isalpha(c);
+}
+
+int isalpha(int c)
+{
+	return islower(c) || isupper(c);
+}
+
+int isascii(int c)
+{
+	return c <= 0x7F;
+}
+
+int isblank(int c)
+{
+	return c == ' ' || c == '\t';
+}
+
+int iscntrl(int c)
+{
+	return c < 32 || c == 0x7F;
+}
+
+int isdigit(int c)
+{
+	return '0' <= c && c <= '9';
+}
+
+int isgraph(int c)
+{
+	return 0x21 <= c && c <= 0x7E;
+}
+
+int islower(int c)
+{
+	return 'a' <= c && c <= 'z';
+}
+
+int isprint(int c)
+{
+	return isgraph(c) || c == ' ';
+}
+
+int ispunct(int c)
+{
+	return isgraph(c) && !isalnum(c);
+}
+
+int isspace(int c)
+{
+	return c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v';
+}
+
+int isupper(int c)
+{
+	return 'A' <= c && c <= 'Z';
+}
+
+int isxdigit(int c)
+{
+	return isdigit(c) || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F');
+}

libc/include/ctype.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+int isalnum(int);
+int isalpha(int);
+int isascii(int);
+int isblank(int);
+int iscntrl(int);
+int isdigit(int);
+int isgraph(int);
+int islower(int);
+int isprint(int);
+int ispunct(int);
+int isspace(int);
+int isupper(int);
+int isxdigit(int);
+
+__END_DECLS