#include "devices.h"

void bus_t::add_device(reg_t addr, abstract_device_t* dev)
{
  // Searching devices via lower_bound/upper_bound
  // implicitly relies on the underlying std::map 
  // container to sort the keys and provide ordered
  // iteration over this sort, which it does. (python's
  // SortedDict is a good analogy)
  devices[addr] = dev;
}

bool bus_t::load(reg_t addr, size_t len, uint8_t* bytes)
{
  // Find the device with the base address closest to but
  // less than addr (price-is-right search)
  auto it = devices.upper_bound(addr);
  if (devices.empty() || it == devices.begin()) {
    // Either the bus is empty, or there weren't 
    // any items with a base address <= addr
    return false;
  }
  // Found at least one item with base address <= addr
  // The iterator points to the device after this, so
  // go back by one item.
  it--;
  return it->second->load(addr - it->first, len, bytes);
}

bool bus_t::store(reg_t addr, size_t len, const uint8_t* bytes)
{
  // See comments in bus_t::load
  auto it = devices.upper_bound(addr);
  if (devices.empty() || it == devices.begin()) {
    return false;
  }
  it--;
  return it->second->store(addr - it->first, len, bytes);
}

std::pair<reg_t, abstract_device_t*> bus_t::find_device(reg_t addr)
{
  // See comments in bus_t::load
  auto it = devices.upper_bound(addr);
  if (devices.empty() || it == devices.begin()) {
    return std::make_pair((reg_t)0, (abstract_device_t*)NULL);
  }
  it--;
  return std::make_pair(it->first, it->second);
}