#include "common.hh"

#include "ro_buffer.hh"

#include <algorithm>

size_t RoBuffer::read(RoBuffer* buf, void* data, size_t len) {
  assert(buf);
  assert(data);
  if (len == 0)
    return 0;
  auto* d = reinterpret_cast<char*>(data);
  size_t got = 0;
  while (true) {
    size_t avail;
    auto want = len - got;
    auto* ptr = buf->rbuf(want, avail);
    if (avail == 0)
      return got;
    if (avail >= want) {
      std::copy_n(ptr, want, d + got);
      buf->rcommit(want);
      return len;
    }
    std::copy_n(ptr, avail, d + got);
    buf->rcommit(avail);
    got += avail;
  }
}