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https://github.com/danbulant/Cosmos
synced 2026-05-19 20:39:01 +00:00
GDT work
This commit is contained in:
kudzu_cp
parent
beb587aea0
commit
967ca09a2c
2 changed files with 102 additions and 34 deletions
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@ -48,6 +48,7 @@ namespace Cosmos.IL2CPU.X86
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new Comment(this, "EBX=multiboot_info ");
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new Comment(this, "EAX=0x2BADB002 - check if it's really Multiboot loader ");
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new Comment(this, " ;- copy mb info - some stuff for you ");
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new Comment(this, "BEGIN - Multiboot Info");
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//new Move { DestinationReg = Registers.ESI, SourceReg = Registers.EBX };
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//new Move { DestinationReg = Registers.EDI, SourceRef = ElementReference.New("MultiBootInfo_Structure") };
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//new Move { DestinationReg = Registers.ECX, SourceValue = 0x58 };
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@ -56,12 +57,7 @@ namespace Cosmos.IL2CPU.X86
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//new Move { DestinationReg = Registers.EBX, SourceRef = ElementReference.New("MultiBootInfo_Structure") };
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new Move { DestinationRef = ElementReference.New("MultiBootInfo_Structure"), DestinationIsIndirect = true, SourceReg = Registers.EBX };
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new Add { DestinationReg = Registers.EBX, SourceValue = 4 };
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new Move
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{
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DestinationReg = Registers.EAX,
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SourceReg = Registers.EBX,
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SourceIsIndirect = true
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};
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new Move { DestinationReg = Registers.EAX, SourceReg = Registers.EBX, SourceIsIndirect = true };
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new Move { DestinationRef = ElementReference.New("MultiBootInfo_Memory_Low"), DestinationIsIndirect = true, SourceReg = Registers.EAX };
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new Add { DestinationReg = Registers.EBX, SourceValue = 4 };
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new Move
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@ -76,6 +72,8 @@ namespace Cosmos.IL2CPU.X86
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DestinationReg = Registers.ESP,
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SourceRef = ElementReference.New("Kernel_Stack")
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};
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new Comment(this, "END - Multiboot Info");
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#if LFB_1024_8
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new Comment("Set graphics fields");
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new Move { DestinationReg = Registers.EBX, SourceRef = ElementReference.New("MultiBootInfo_Structure"), SourceIsIndirect = true };
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@ -86,9 +84,8 @@ namespace Cosmos.IL2CPU.X86
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new Move { DestinationReg = Registers.EAX, SourceReg = Registers.EBX, SourceIsIndirect = true, SourceDisplacement = 80 };
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new Move { DestinationRef = ElementReference.New("MultibootGraphicsRuntime_VbeMode"), DestinationIsIndirect = true, SourceReg = Registers.EAX };
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#endif
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new Comment(this, "some more startups todo");
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// SSE init
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new Comment(this, "BEGIN - SSE Init");
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// CR4[bit 9]=1, CR4[bit 10]=1, CR0[bit 2]=0, CR0[bit 1]=1
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new Move { DestinationReg = Registers.EAX, SourceReg = Registers.CR4 };
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new Or { DestinationReg = Registers.EAX, SourceValue = 0x100 };
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@ -104,7 +101,7 @@ namespace Cosmos.IL2CPU.X86
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new And { DestinationReg = Registers.EAX, SourceValue = 1 };
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new Move { DestinationReg = Registers.CR0, SourceReg = Registers.EAX };
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// END SSE INIT
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new Comment(this, "END - SSE Init");
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if (mComNumber > 0)
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{
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@ -118,7 +115,7 @@ namespace Cosmos.IL2CPU.X86
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// Jump to Kernel entry point
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new Call { DestinationLabel = EntryPointName };
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// After Kernel is done, sit here and halt till next IRQ.
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new Comment(this, "Kernel done - loop till next IRQ");
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new Label(".loop");
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new ClrInterruptFlag();
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new Halt();
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@ -6,33 +6,104 @@ using CPUx86 = Cosmos.Compiler.Assembler.X86;
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using System.Collections.Generic;
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namespace Cosmos.Core.Plugs.Assemblers {
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public class CreateGDT : AssemblerMethod {
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public override void AssembleNew(object aAssembler, object aMethodInfo) {
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var xAssembler = (Assembler)aAssembler;
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xAssembler.DataMembers.Add(new CPUAll.DataMember("_NATIVE_GDT_Contents"
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, new byte[]
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{0,0,0,0,0,0,0,0 // Null Segment
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, 0xFF, 0xFF, 0, 0, 0, 0x99, 0xCF, 0 // Code Segment
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, 0xFF,0xFF,0,0,0,0x93,0xCF,0})); // Data Segment
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xAssembler.DataMembers.Add(new CPUAll.DataMember("_NATIVE_GDT_Pointer", new ushort[] { 0x17, 0, 0 }));
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public class CreateGDT : AssemblerMethod {
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// http://wiki.osdev.org/Global_Descriptor_Table
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// http://http://wiki.osdev.org/GDT_Tutorial
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// http://www.osdever.net/bkerndev/Docs/gdt.htm
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new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer") };
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new CPUx86.Move { DestinationRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer"), DestinationIsIndirect = true, DestinationDisplacement = 2, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Contents") };
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//TODO: Modify this to support the flags and access as individual input rather
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// than requiring user to pass pre-calculated numbers.
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protected byte[] Descriptor(UInt32 aBase, UInt32 aSize, bool aCode) {
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// Limit is a confusing word. Is it the max physical address or size?
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// In fact it is the size, and 286 docs actually refer to it as size
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// rather than limit.
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// It is also size - 1, else there would be no way to specify
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// all of RAM, and a limit of 0 is invalid.
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new CPUAll.Label(".RegisterGDT");
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new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer") };
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new CPUx86.Lgdt { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true };
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var xResult = new byte[8];
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// Check the limit to make sure that it can be encoded
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if ((aSize > 65536) && (aSize & 0x0FFF) != 0x0FFF) {
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// If larger than 16 bit, must be an even page (4kb) size
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throw new Exception("Invalid size in GDT descriptor.");
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}
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// Flags nibble
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// 7: Granularity
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// 0 = bytes
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// 1 = 4kb pages
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// 6: 1 = 32 bit mode
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// 5: 0 - Reserved
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// 4: 0 - Reserved
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xResult[6] = 0x40;
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if (aSize > 65536) {
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// Set page sizing instead of byte sizing
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aSize = aSize >> 12;
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xResult[6] = (byte)(xResult[6] | 0x80);
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}
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xResult[0] = (byte)(aSize & 0xFF);
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xResult[1] = (byte)((aSize >> 8) & 0xFF);
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xResult[6] = (byte)(xResult[6] | ((aSize >> 16) & 0x0F));
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new CPUx86.Move { DestinationReg = CPUx86.Registers.AX, SourceValue = 0x10 };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.DS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.ES, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.FS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.GS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.SS, SourceReg = CPUx86.Registers.AX };
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xResult[2] = (byte)(aBase & 0xFF);
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xResult[3] = (byte)((aBase >> 8) & 0xFF);
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xResult[4] = (byte)((aBase >> 16) & 0xFF);
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xResult[7] = (byte)((aBase >> 24) & 0xFF);
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// Force reload of code segment
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new CPUx86.JumpToSegment { Segment = 8, DestinationLabel = "flush__GDT__table" };
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new CPUAll.Label("flush__GDT__table");
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}
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xResult[5] = (byte)(
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// Bit 7: Present, must be 1
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0x80 |
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// Bit 6-5: Privilege, 0=kernel, 3=user
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0x00 |
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// Reserved, must be 1
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0x10 |
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// Bit 3: 1=Code, 0=Data
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(aCode ? 0x08 : 0x00) |
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// Bit 2: Direction/Conforming
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0x00 |
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// Bit 1: R/W Data (1=Writeable, 0=Read only) Code (1=Readable, 0=Not readable)
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0x02 |
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// Bit 0: Accessed - Set to 0. Updated by CPU later.
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0x00
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);
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return xResult;
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}
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public override void AssembleNew(object aAssembler, object aMethodInfo) {
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var xAsm = (Assembler)aAssembler;
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var xGDT = new List<byte>();
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// Null Segment - Selector 0x00
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// Not used, but required by many emulators.
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xGDT.AddRange(new byte[8] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 });
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// Code Segment
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byte xCodeSelector = (byte)xGDT.Count;
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xGDT.AddRange(Descriptor(0x00000000, 0xFFFFFFFF, true));
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// Data Segment - Selector 0x0B
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byte xDataSelector = (byte)xGDT.Count;
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xGDT.AddRange(Descriptor(0x00000000, 0xFFFFFFFF, false));
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xAsm.DataMembers.Add(new CPUAll.DataMember("_NATIVE_GDT_Contents", xGDT.ToArray()));
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xAsm.DataMembers.Add(new CPUAll.DataMember("_NATIVE_GDT_Pointer", new ushort[] { 0x17, 0, 0 }));
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new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer") };
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new CPUx86.Move { DestinationRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer"), DestinationIsIndirect = true, DestinationDisplacement = 2, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Contents") };
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new CPUAll.Label(".RegisterGDT");
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new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceRef = CPUAll.ElementReference.New("_NATIVE_GDT_Pointer") };
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new CPUx86.Lgdt { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.AX, SourceValue = 0x10 };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.DS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.ES, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.FS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.GS, SourceReg = CPUx86.Registers.AX };
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new CPUx86.Move { DestinationReg = CPUx86.Registers.SS, SourceReg = CPUx86.Registers.AX };
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new CPUAll.Comment("Force reload of code segment");
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new CPUx86.JumpToSegment { Segment = 0x08, DestinationLabel = "flush__GDT__table" };
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new CPUAll.Label("flush__GDT__table");
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}
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}
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}
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