#ifndef BASE64_C
#define BASE64_C

#include <stddef.h>

static const char b64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";

void base64_encode(
  const unsigned char *in,
  size_t len,
  char *out
) {
  size_t i, j = 0;

  for (i = 0; i < len; i += 3) {
    unsigned v = in[i] << 16;

    if (i + 1 < len) v |= in[i + 1] << 8;
    if (i + 2 < len) v |= in[i + 2];

    out[j++] = b64[(v >> 18) & 63];
    out[j++] = b64[(v >> 12) & 63];

    out[j++] = (i + 1 < len) ? b64[(v >> 6) & 63] : '=';
    out[j++] = (i + 2 < len) ? b64[v & 63] : '=';
  }

  out[j] = 0;
}

#endif // BASE64_C