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// license:BSD-3-Clause
// copyright-holders:Vas Crabb
/***************************************************************************
GBX file format helpers
***************************************************************************/
#include "emu.h"
#include "gbxfile.h"
#include <cstring>
namespace bus::gameboy::gbxfile {
bool get_data(
memory_region *region,
leader_1_0 &leader,
u8 const *&extra,
u32 &extralen)
{
// no region, no dice
if (!region)
return false;
// needs to contain enough data for the trailer at the very least
auto const bytes(region->bytes());
if (bytes < sizeof(trailer))
return false;
// check for supported format
u8 *const base(®ion->as_u8());
trailer t;
std::memcpy(&t, &base[bytes - sizeof(t)], sizeof(t));
t.swap();
if ((MAGIC_GBX != t.magic) || (1 != t.ver_maj))
return false;
// check that the footer fits and the leader doesn't overlap the trailer
if ((bytes < t.size) || ((sizeof(leader) + sizeof(t)) > t.size))
return false;
// get leader in host byte order
std::memcpy(&leader, &base[bytes - t.size], sizeof(leader));
leader.swap();
// get pointer to extra data if there's any
extralen = t.size - sizeof(leader) - sizeof(t);
if (extralen)
extra = &base[bytes - t.size + sizeof(leader)];
else
extra = nullptr;
// all good
return true;
}
} // namespace bus::gameboy::gbxfile
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