Implemented some basic libc functions and a text console

libc/ctype/ctype.c

@@ -0,0 +1,94 @@
+/*
+ *  asbestOS: The best operating system ever made.
+ *  Copyright (C) 2017 Max Wash
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdbool.h>
+#include <stdint.h>
+
+static unsigned int random_seed = 53455346;
+
+int isupper(int c) { return (c >= 65 && c <= 90); }
+
+int islower(int c) { return (c >= 97 && c <= 122); }
+
+int toupper(int c) {
+    if (!islower(c)) {
+        return c;
+    }
+
+    return c - 32;
+}
+
+int tolower(int c) {
+    if (!isupper(c)) {
+        return c;
+    }
+
+    return c + 32;
+}
+
+int isdigit(int c) { return (c >= 48 && c <= 57); }
+
+int isalpha(int c) { return (c >= 65 && c <= 90) || (c >= 97 && c <= 122); }
+
+int isalnum(int c) { return isalpha(c) | isdigit(c); }
+
+int iscntrl(int c) { return (c <= 31) || (c == 127); }
+
+int isprint(int c) { return (c >= 32 && c <= 126) || (c >= 128 && c <= 254); }
+
+int isgraph(int c) { return isprint(c) && c != 32; }
+
+int ispunct(int c) { return isgraph(c) && !isalnum(c); }
+
+int isspace(int c) {
+    return (c == ' ') || (c == '\t') || (c == '\n') || (c == '\v') ||
+           (c == '\f') || (c == '\r');
+}
+
+int isxdigit(int c) {
+    return isdigit(c) || (c >= 65 && c <= 70) || (c >= 97 && c <= 102);
+}
+
+bool fill_random(unsigned char *buffer, unsigned int size) {
+    if (!buffer || !size) {
+        return false;
+    }
+
+    for (uint32_t i = 0; i < size; i++) {
+        uint32_t next = random_seed;
+        uint32_t result;
+
+        next *= 1103515245;
+        next += 12345;
+        result = (uint32_t)(next / 65536) % 2048;
+
+        next *= 1103515245;
+        next += 12345;
+        result <<= 10;
+        result ^= (uint32_t)(next / 65536) % 1024;
+
+        next *= 1103515245;
+        next += 12345;
+        result <<= 10;
+        result ^= (uint32_t)(next / 65536) % 1024;
+        random_seed = next;
+
+        buffer[i] = (uint8_t)(result % 256);
+    }
+
+    return true;
+}