SparrowOSTS_121127.ISO

SparrowOS/Demo/Lectures/PageTableEntries1.CPP

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+//What's funner than page tables for programmers to play with!!
+
+//This changes a page table entry for VGA graphics memory.
+//SparrowOS keeps a cached copy of VGA memory in
+//$LK,"gr_screen_image","MN:gr_screen_image"$.  See $LK,"GrUpdateVGAGraphics","MN:GrUpdateVGAGraphics"$.
+
+//SparrowOS used 4096 size pages for memory below addr 2 Meg
+//and 2 Meg pages above two Meg.  See $LK,"MemPageSize","MN:MemPageSize"$() and $LK,"INIT_MEMORY","FF:::/SparrowOS/OSMain/Memory.CPP.Z,SYS_INIT_MEM"$.
+
+
+U0 PageTableDemo1()
+{
+  I64 *pte=MemPtAtPageTableEntry(VGA_GRAPHIC_MEM_BASE),p0,p1;
+  "Page table entries for VGA screen memory\n";
+  DocD(pte);
+  PressAKey;
+
+  p0=pte[0];
+  p1=pte[1];
+  pte[0]=p1;
+  pte[1]=p0;
+  InvlPg(VGA_GRAPHIC_MEM_BASE); //Invalidate translation look aside buffer (TLB).
+  InvlPg(VGA_GRAPHIC_MEM_BASE+0x1000);
+
+//Use this if you wish to change
+//the page table register.
+
+//  SetRAX(0x100000+0x1000*(NUM_PML1+NUM_PML2+NUM_PML3));
+//  asm {MOV_CR3_EAX}
+
+//<CTRL-ALT-F> will flush screen VGA cache.
+  VGAFlush;
+  PressAKey;
+
+  pte[0]=p0;
+  pte[1]=p1;
+  InvlPg(VGA_GRAPHIC_MEM_BASE);
+  InvlPg(VGA_GRAPHIC_MEM_BASE+0x1000);
+
+//<CTRL-ALT-F> will flush screen VGA cache.
+  VGAFlush;
+}
+
+PageTableDemo1;
+
+//See $LK,"MemBlks2MegAlloc","MN:MemBlks2MegAlloc"$(), $LK,"MemBlks2MegFree","MN:MemBlks2MegFree"$() for page aligned allocations.
+//See $LK,"CBlkPool","MN:CBlkPool"$, $LK,"CHeapCtrl","MN:CHeapCtrl"$, $LK,"sys_code_bp","MN:sys_code_bp"$, $LK,"sys_data_bp","MN:sys_data_bp"$.
+//See $LK,"Memory","HI:Memory"$