/* Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
   Released under the terms of the MIT License. See LICENSE for details. */

#include <stdlib.h>
#include <string.h>

#include "util.h"

#if defined __APPLE__
    #include <mach/mach_time.h>
#elif defined __linux__
    #include <time.h>
    #ifndef CLOCK_MONOTONIC
        #error "Unsupported operating system or compiler."
    #endif
#else
    #error "Unsupported operating system or compiler."
#endif

#define NS_PER_SEC 1000000000

/*
    Convert a BCD-encoded hexadecimal number to decimal.
*/
uint8_t bcd_decode(uint8_t num)
{
    return ((num >> 4) * 10) + (num & 0x0F);
}

/*
    Return monotonic time, in nanoseconds.
*/
uint64_t get_time_ns()
{
#if defined __APPLE__
    static mach_timebase_info_data_t tb_info;
    if (tb_info.denom == 0)
        mach_timebase_info(&tb_info);
    // Apple's docs pretty much say "screw overflow" here...
    return mach_absolute_time() * tb_info.numer / tb_info.denom;
#elif defined __linux__
    struct timespec spec;
    clock_gettime(CLOCK_MONOTONIC, &spec);
    return spec.tv_sec * NS_PER_SEC + spec.tv_nsec;
#endif
}

/*
    Return the name of the region encoded by the given region code.

    The given code should not be larger than one nibble. NULL is returned if
    the region code is invalid.

    Region code information is taken from:
    http://www.smspower.org/Development/ROMHeader
*/
const char* region_code_to_string(uint8_t code)
{
    switch (code) {
        case 3:  return "SMS Japan";
        case 4:  return "SMS Export";
        case 5:  return "GG Japan";
        case 6:  return "GG Export";
        case 7:  return "GG International";
        default: return NULL;
    }
}

/*
    Return the region code that encodes the given region name.

    0 is returned if the name is not known. This is not a valid region code.
*/
uint8_t region_string_to_code(const char *name)
{
    if (!strncmp(name, "SMS ", 4)) {
        name += 4;
        if (!strcmp(name, "Japan"))
            return 3;
        if (!strcmp(name, "Export"))
            return 4;
    } else if (!strncmp(name, "GG ", 3)) {
        name += 3;
        if (!strcmp(name, "Japan"))
            return 5;
        if (!strcmp(name, "Export"))
            return 6;
        if (!strcmp(name, "International"))
            return 7;
    }
    return 0;
}