static void stbi__start_mem(stbi__context *s, stbi_uc const *buffer, int len)
{
   s->io.read = NULL;
   s->read_from_callbacks = 0;
   s->callback_already_read = 0;
   s->img_buffer = s->img_buffer_original = (stbi_uc *) buffer;
   s->img_buffer_end = s->img_buffer_original_end = (stbi_uc *) buffer+len;
}
Unknown