TempleOSCDV4.03.ISO

Demo/Lectures/Mem/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.
+TempleOS keeps a cached copy of VGA memory in
+$LK,"gr.screen_image",A="MN:CGrGlbls"$.  See $LK,"GrUpdateVGAGraphics",A="MN:GrUpdateVGAGraphics"$.
+
+TempleOS used 4096 size pages for memory below addr 2 Meg
+and 2 Meg pages above two Meg.  See $LK,"MemPageSize",A="MN:MemPageSize"$() and $LK,"INIT_MEMORY",A="FF:::/Kernel/Mem/PageTables.CPP,SYS_INIT_MEM"$.
+*/
+
+U0 PageTableDemo1()
+{
+  I64 *pte=MemPageTable(VGAM_GRAPHICS),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(VGAM_GRAPHICS); //Invalidate translation look aside buffer (TLB).
+  InvlPg(VGAM_GRAPHICS+0x1000);
+
+  //Use this if you wish to change
+  //the page table reg.
+
+  //  SetRAX(0x100000+0x1000*(MEM_NUM_PML1+MEM_NUM_PML2+MEM_NUM_PML3));
+  //  MOV_CR3_EAX
+
+  //<CTRL-ALT-v> will flush screen VGA cache.
+  VGAFlush;
+  PressAKey;
+
+  pte[0]=p0;
+  pte[1]=p1;
+  InvlPg(VGAM_GRAPHICS);
+  InvlPg(VGAM_GRAPHICS+0x1000);
+
+  //<CTRL-ALT-v> will flush screen VGA cache.
+  VGAFlush;
+}
+
+PageTableDemo1;
+
+//See $LK,"CBlkPool",A="MN:CBlkPool"$, $LK,"CHeapCtrl",A="MN:CHeapCtrl"$, $LK,"sys_code_bp",A="MN:sys_code_bp"$ and $LK,"sys_data_bp",A="MN:sys_data_bp"$.
+//See $LK,"Memory Overview",A="FI:::/Doc/MemOverview.TXT"$ and $LK,"Memory Routines",A="HI:Memory"$.