GDLWXStream::GDLWXStream( int width, int height )
: GDLGStream( width, height, "wxwidgets")
, m_dc(NULL)
, m_bitmap(NULL)
, m_width(width), m_height(height)
, gdlWindow(NULL)
{
m_dc = new wxMemoryDC();
m_bitmap = new wxBitmap( width, height, -1 );
m_dc->SelectObject( *m_bitmap);
if( !m_dc->IsOk())
{
m_dc->SelectObject( wxNullBitmap );
delete m_bitmap;
delete m_dc;
throw GDLException("GDLWXStream: Failed to create DC.");
}
//::plstream();
// sdev( "wxwidgets" );
spage( 0.0, 0.0, m_width, m_height, 0, 0 );
// SETOPT( "text", "1" ); // use freetype?
// SETOPT( "smooth", "1" ); // antialiased text?
this->plstream::init();
plP_esc( PLESC_DEVINIT, (void*)m_dc );
plstream::set_stream();
// plgpls( &thePls); // in GDLGStream
}
setup_paging()
{
int i;
//设置页表的初始地址
pg_dir = (int *)((((int)&pg_mem) + 4095) & -4096);
//分四页，每页1024*4个字节，即4KB
pg0 = pg_dir + 1024;
pg1 = pg0 + 1024;
pg2 = pg1 + 1024;
pg3 = pg2 + 1024;
pg_dir[0] = (int)pg0 | PTE_P | PTE_W | PTE_U; // identity map 16M
pg_dir[1] = (int)pg1 | PTE_P | PTE_W | PTE_U;
pg_dir[2] = (int)pg2 | PTE_P | PTE_W | PTE_U;
pg_dir[3] = (int)pg3 | PTE_P | PTE_W | PTE_U;
//这一步是用来对齐的吗？一个物理内存块是4KB，页表初始地址管理四个页块，而pg0是从pg_dir+1024开始的，因此把4~1024这部分赋值为0
for (i=4;i<1024;i++) pg_dir[i] = 0;
//初始化四个页面。每个页起初都是可用的，又因为一个4KB页为2^12，因此页块的物理地址低12位都是0，用于存储页的状态（PTE_P | PTE_W | PTE_U）。
for (i=0;i<4096;i++) pg0[i] = (i<<12) | PTE_P | PTE_W | PTE_U; // trick to write all 4 contiguous pages
//页起始地址设置
pdir(pg_dir);
//设置页机制(使能)
spage(1);
}