#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

size_t memset (void* dst, uint8_t b, size_t n) {
  uint8_t* dst1 = dst;
  size_t i;
  for (i = 0; i < n; i++)
    dst1[i] = b;
  return i;
}

size_t memcpy (void* dst, const void* src, size_t n) {
  uint8_t* dst1 = dst;
  const uint8_t* src1 = src;
  size_t i;
  for (i = 0; i < n; i++)
    dst1[i] = src1[i];
  return i;
}

// SOURCE: https://stackoverflow.com/a/48967408
void strncpy (char* dst, const char* src, size_t n) {
  size_t i = 0;
  while (i++ != n && (*dst++ = *src++))
    ;
}

size_t strlen (const char* str) {
  const char* s;
  for (s = str; *s; ++s)
    ;
  return (s - str);
}

int memcmp (const void* s1, const void* s2, size_t n) {
  unsigned char* p = (unsigned char*)s1;
  unsigned char* q = (unsigned char*)s2;

  while (n--) {
    if (*p != *q) {
      return (int)*p - (int)*q;
    }
    p++, q++;
  }
  return 0;
}

void strtokenize (const char* str, char delim, void* ctx, strtokenize_cb_func_t cb) {
  const char* start = str;
  const char* end;

  while (*start) {
    while (*start == delim && *start)
      start++;

    if (!*start)
      break;

    end = start;
    while (*end != delim && *end)
      end++;

    if (!cb (ctx, start, (size_t)(end - start)))
      break;

    start = end;
  }
}

/* https://stackoverflow.com/a/34873406 */
int strcmp (const char* s1, const char* s2) {
  while (*s1 && (*s1 == *s2)) {
    s1++;
    s2++;
  }
  return *(const unsigned char*)s1 - *(const unsigned char*)s2;
}

/* https://stackoverflow.com/a/2490637 */
char* strcat (char* dest, const char* src) {
  char* rdest = dest;

  while (*dest)
    dest++;

  while ((*dest++ = *src++))
    ;

  return rdest;
}

int isalnum (int c) { return isalpha (c) || isdigit (c); }

int isalpha (int c) { return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'); }

int iscntrl (int c) { return (c >= 0 && c <= 32) || (c == 127); }

int isdigit (int c) { return (c >= '0' && c <= '9'); }

int isgraph (int c) { return (c > 32 && c <= 126); }

int islower (int c) { return (c >= 'A' && c <= 'z'); }

int isprint (int c) { return (c >= 32 && c <= 126); }

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 (c >= 'A' && c <= 'Z'); }

int isxdigit (int c) { return isdigit (c) || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f'); }

int isascii (int c) { return (c >= 0 && c <= 127); }

int isblank (int c) { return (c == ' ' || c == '\t'); }