/*
 *  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;
}