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sead

sead is Nintendo's C++ standard library. It provides basic data structures such as strings and tree maps and many other essential components (e.g. threads, critical sections, file IO, etc.)

Strings​

sead::SafeString constructor​

x.vptr = &sead::SafeString::vt;
x.cstr = "some string here";

⬇️

sead::SafeString x = "some string here";

Note that the SafeString constructor is also implicitly called whenever a string literal is converted into an sead::SafeString (because it was passed as an argument to a function that expects an sead::SafeString for example).

sead::FixedSafeString<N> constructor​

A sead::FixedSafeString<N> is a fixed-length SafeString. It derives from sead::BufferedSafeString (which derives from sead::SafeString) and contains a char[N] buffer right after the length.

Note: the field assignments may be in a different order.

x._.cstr = (char*)&xxx; // some buffer right after `x`
x._.vptr = &`vtable for'sead::BufferedSafeStringBase<char>;
x.length = N; // where N is a number
sead::BufferedSafeStringBase<char>::assureTerminationImpl_(&x);
*x._.cstr = sead::SafeStringBase<char>::cNullChar;
x._.vptr = ...;

⬇️

sead::FixedSafeString<N> x;

sead::SafeString::cstr​

sead::SafeString::cstr returns a const char*, like std::string::c_str. You can expect it to be called whenever a SafeString needs to be passed to a function that takes a C-style string (const char*).

string.vptr->assureTermination(...);
const char* ptr = string.cstr;
// do stuff with string.cstr
// note that the variable may not exist in the pseudocode

⬇️

const char* ptr = string.cstr();

sead::SafeString::calcLength​

x.vptr->assureTermination(&x);
v12 = x.cstr;
str_length = 0LL;
v14 = (signed __int64)(v12 + 1);
while ( v12[str_length] != sead::SafeStringBase<char>::cNullChar )
{
  if ( *(unsigned __int8 *)(v14 + str_length) == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
  {
    LODWORD(str_length) = str_length + 1;
    break;
  }
  if ( *(unsigned __int8 *)(v14 + str_length + 1) == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
  {
    LODWORD(str_length) = str_length + 2;
    break;
  }
  v15 = str_length + 2;
  str_length += 3LL;
  if ( v15 >= 0x80000 )
  {
    LODWORD(str_length) = 0;
    break;
  }
}

⬇️

s32 str_length = x.calcLength();

Note that this function is commonly called from other sead::SafeString inline functions.

sead::BufferedSafeString::copy​

dest_cstr = dest_safestring.cstr;
source_safestring.vptr->assureTermination(&source_safestring);
source_cstr = source_safestring.cstr;
if ( dest_cstr != source_cstr )
{
  source_safestring.vptr->assureTermination(&source_safestring);
  v6 = 0LL;
  v7 = (signed __int64)(source_safestring.cstr + 1);
  while ( source_safestring.cstr[v6] != sead::SafeStringBase<char>::cNullChar )
  {
    if ( *(unsigned __int8 *)(v7 + v6) == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
    {
      LODWORD(v6) = v6 + 1;
      break;
    }
    if ( *(unsigned __int8 *)(v7 + v6 + 1) == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
    {
      LODWORD(v6) = v6 + 2;
      break;
    }
    v8 = v6 + 2;
    v6 += 3LL;
    if ( v8 >= 0x80000 )
    {
      LODWORD(v6) = 0;
      break;
    }
  }
  if ( (signed int)v6 >= dest_safestring.length )
    LODWORD(v6) = dest_safestring.length - 1;
  v9 = (signed int)v6;
  memcpy_0(dest_str, source_str, (signed int)v6);
  dest_str[v9] = sead::SafeStringBase<char>::cNullChar;
}

⬇️

dest_safestring = source_safestring;

Note: the while loop comes from an inlined version of sead::SafeString::calcLength.

sead::SafeString::startsWith​

if ( sead::SafeStringBase<char>::cNullChar != 'E' )
{
  v11 = string->cstr;
  v12 = "nemy";
  v13 = 'E';
  while ( (unsigned __int8)*v11 == v13 )
  {
    v14 = (unsigned __int8)*v12++;
    v13 = v14;
    ++v11;
    if ( v14 == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
      goto LABEL;
  }
  foo();
}
LABEL:
  bar();

⬇️

if (string.startsWith("Enemy"))
    bar();
else
    foo();

This weird optimization can lead to malformed strings in Hex-Rays's output for strings that contain Japanese or multibyte characters more generally.

sead::SafeString::isEqual / operator==​

enemy->vptr->assureTermination(enemy);
enemy->vptr->assureTermination(enemy);
v15 = enemy->cstr;
if ( v15 == "Enemy_Assassin_Junior" )
{
LABEL_37:
  foo();
}
else
{
  v16 = 0LL;
  do
  {
    v17 = (unsigned __int8)v15[v16];
    if ( v17 != (unsigned __int8)aEnemyAssassinJ[v16] )
      break;
    if ( v17 == (unsigned __int8)sead::SafeStringBase<char>::cNullChar )
      goto LABEL_37;
    ++v16;
  }
  while ( v16 < 0x80001 );
  bar();
}

⬇️

// enemy is a sead::SafeString or a derived class
if (enemy == "Enemy_Assassin_Junior")
    foo();
else
    bar();

sead::SafeString::isEmpty​

if ( *string.cstr == sead::SafeStringBase<char>::cNullChar )

⬇️

if (string.isEmpty())

ScopedLock​

sead::CriticalSection::lock(foo);
bar();
sead::CriticalSection::unlock(foo);

⬇️

{
    auto lock = sead::makeScopedLock(foo);
    bar();
}

Buffer​

An sead::Buffer is a non-owning view over a contiguous array of values: it is essentially a wrapper around a raw pointer and a size count.

sead::Buffer::allocBufferAssert​

In this example, 0x108 is the size of each item.

v9 = 0x108LL * (signed int)num_tables;
v10 = is_mul_ok((signed int)num_tables, 0x108uLL) == 0;
v11 = __CFADD__(v9, 8LL);
v12 = v9 + 8;
if ( v11 )
  v13 = 1;
else
  v13 = 0;
if ( (unsigned int)v10 | v13 )
  size = 1LL;
else
  size = v12;
v15 = (char *)operator new[](size, &heap->_, 8u, &std::nothrow);
if ( v15 )
{
    *(_QWORD *)v15 = (signed int)num_tables;
    v16 = (BdropTable *)((char*)v15 + 8);

    // loop over each item and call a constructor
    // note: the constructor may be inlined

    // at the end:
    buffer->size = num_tables;
    buffer->data = v16;
}

⬇️

buffer->allocBufferAssert(num_tables, heap);

Notice how the object count is stored in the first 8 bytes of the allocation: this is because in this specific example, the allocated objects are not trivially destructible.

Another code pattern with a multiplication that looks different:

v13 = operator new[](0x28LL * (unsigned int)count + 8, &heap->_, 8u, &std::nothrow);
if ( v13 )
{
  *v13 = count;
  v14 = (signed __int64)(v13 + 1);
  // loop over each item and call a constructor
  // note: the constructor may be inlined
  // at the end:
  *buffer = count;
  *((_QWORD *)buffer + 1) = v14;
}

⬇️

buffer->allocBufferAssert(count, heap);

If each item is a trivially constructible type (e.g. the buffer stores ints or pointers) then there will be no loop that calls a constructor and the compiler will not store the size of the array in the first 8 bytes of the allocation.

sead::Buffer::operator[]​

With automatic bounds checks.

if ( buffer->size <= i )
    item = buffer->data;
else
    item = buffer->data[i];

⬇️

item = buffer[i];

RTTI (Runtime Type Info)​

sead::DynamicCast​

some_ptr = ...;
x = __ldar(...);  // usually a guard variable, but the variable is not always named
another_ptr = some_ptr;
if ( (x & 1) == 0 && _cxa_guard_acquire_0(...))  // the same guard variable
{
  ... = &...;
  _cxa_guard_release_0(...);  // the same guard variable
}
if ( another_ptr && another_ptr->checkDerivedRuntimeTypeInfo(another_ptr, ...) )
{
  // code that uses another_ptr
}

⬇️

if (auto* another_ptr = sead::DynamicCast<T>(some_ptr))
  ...

T is a derived type that should be related to the type of the original pointer.