User:Johnburger/Demo/Ints/IDT

Hard-coding the Interrupt Descriptor Table in data rather than in code saved me vital space in the Boot sector, since I wanted the IDT fully set up (to at the very least display Faults) upon the switch to Protected Mode.

The below table makes extensive use of the Desc macros, making for very clean and straightforward source code. It's not so obvious with the GDT code, but they're used there too. As for the LDTs... nope! Too hard!

Demo/Ints/IDT.inc

;
; Ints/IDT.inc
;
 
; This is the Interrupt Descriptor Table for the system.
; For each potential interrupt, it points to the relevant routine.
; Note that only the first 32 Intel-reserved interrupts, and the 16 Interrupt
; ReQuest IRQs, are set up. Although sufficient memory has been allocated for
; all 256 interrupts, the IDT is only initialised with these first 48.
;
; EDIT: I decided to add two more, to be called from User mode:
; * INT 48 is a User-mode HLT replacement;
; * INT 49 is a Yield call - go to next Task.
 
                SEGMENT         IDT  VSTART=0  ALIGN=16
 
                USE32
 
IDT.Trap        EQU             Type.Sys(Trap, DPL0, 386)
IDT.Int         EQU             Type.Sys(Int,  DPL0, 386)
IDT.User        EQU             Type.Sys(Trap, DPL3, 386)
 
IDT:
IDT.Divide      Desc.Sys        GDT.Ints, Ints.Int0, IDT.Trap     ; Int 00h
IDT.Single      Desc.Sys        GDT.Ints, Ints.Int1, IDT.Trap     ; Int 01h
IDT.NMI         Desc.Sys        GDT.Ints, Ints.Int2, IDT.Trap     ; Int 02h
IDT.Debug       Desc.Sys        GDT.Ints, Ints.Int3, IDT.Trap     ; Int 03h
IDT.INTO        Desc.Sys        GDT.Ints, Ints.Int4, IDT.Trap     ; Int 04h
IDT.BOUND       Desc.Sys        GDT.Ints, Ints.Int5, IDT.Trap     ; Int 05h
IDT.BadOp       Desc.Sys        GDT.Ints, Ints.Int6, IDT.Trap     ; Int 06h
IDT.No387       Desc.Sys        GDT.Ints, Ints.Int7, IDT.Trap     ; Int 07h
IDT.Double      Desc.Sys        GDT.Ints, Ints.Int8, IDT.Trap     ; Int 08h
IDT.Bad387      Desc.Sys        GDT.Ints, Ints.Int9, IDT.Trap     ; Int 09h
IDT.BadTSS      Desc.Sys        GDT.Ints, Ints.Int10, IDT.Trap    ; Int 0Ah
IDT.NoSeg       Desc.Sys        GDT.Ints, Ints.Int11, IDT.Trap    ; Int 0Bh
IDT.BadStack    Desc.Sys        GDT.Ints, Ints.Int12, IDT.Trap    ; Int 0Ch
IDT.GPF         Desc.Sys        GDT.Ints, Ints.Int13, IDT.Trap    ; Int 0Dh
IDT.Page        Desc.Sys        GDT.Ints, Ints.Int14, IDT.Trap    ; Int 0Eh
IDT.15          Desc.Sys        GDT.Ints, Ints.Int15, IDT.Trap    ; Int 0Fh
IDT.Float       Desc.Sys        GDT.Ints, Ints.Int16, IDT.Trap    ; Int 10h
IDT.Align       Desc.Sys        GDT.Ints, Ints.Int17, IDT.Trap    ; Int 11h
IDT.Machine     Desc.Sys        GDT.Ints, Ints.Int18, IDT.Trap    ; Int 12h
IDT.SIMD        Desc.Sys        GDT.Ints, Ints.Int19, IDT.Trap    ; Int 13h
IDT.VM          Desc.Sys        GDT.Ints, Ints.Int20, IDT.Trap    ; Int 14h
IDT.21          Desc.Sys        GDT.Ints, Ints.Int21, IDT.Trap    ; Int 15h
IDT.22          Desc.Sys        GDT.Ints, Ints.Int22, IDT.Trap    ; Int 16h
IDT.23          Desc.Sys        GDT.Ints, Ints.Int23, IDT.Trap    ; Int 17h
IDT.24          Desc.Sys        GDT.Ints, Ints.Int24, IDT.Trap    ; Int 18h
IDT.25          Desc.Sys        GDT.Ints, Ints.Int25, IDT.Trap    ; Int 19h
IDT.26          Desc.Sys        GDT.Ints, Ints.Int26, IDT.Trap    ; Int 1Ah
IDT.27          Desc.Sys        GDT.Ints, Ints.Int27, IDT.Trap    ; Int 1Bh
IDT.28          Desc.Sys        GDT.Ints, Ints.Int28, IDT.Trap    ; Int 1Ch
IDT.29          Desc.Sys        GDT.Ints, Ints.Int29, IDT.Trap    ; Int 1Dh
IDT.Security    Desc.Sys        GDT.Ints, Ints.Int30, IDT.Trap    ; Int 1Eh
IDT.31          Desc.Sys        GDT.Ints, Ints.Int31, IDT.Trap    ; Int 1Fh
 
IDT.Timer       Desc.Sys        GDT.Ints, Ints.IRQ0, IDT.Int      ; Int 20h
IDT.Key         Desc.Sys        GDT.Ints, Ints.IRQ1, IDT.Int      ; Int 21h
IDT.Cascade     Desc.Sys        GDT.Ints, Ints.IRQ2, IDT.Int      ; Int 22h
IDT.COM2        Desc.Sys        GDT.Ints, Ints.IRQ3, IDT.Int      ; Int 23h
IDT.COM1        Desc.Sys        GDT.Ints, Ints.IRQ4, IDT.Int      ; Int 24h
IDT.IRQ5        Desc.Sys        GDT.Ints, Ints.IRQ5, IDT.Int      ; Int 25h
IDT.Floppy      Desc.Sys        GDT.Ints, Ints.IRQ6, IDT.Int      ; Int 26h
IDT.Printer     Desc.Sys        GDT.Ints, Ints.IRQ7, IDT.Int      ; Int 27h
IDT.RTC         Desc.Sys        GDT.Ints, Ints.IRQ8, IDT.Int      ; Int 28h
IDT.IRQ9        Desc.Sys        GDT.Ints, Ints.IRQ9, IDT.Int      ; Int 29h
IDT.IRQ10       Desc.Sys        GDT.Ints, Ints.IRQ10, IDT.Int     ; Int 2Ah
IDT.IRQ11       Desc.Sys        GDT.Ints, Ints.IRQ11, IDT.Int     ; Int 2Bh
IDT.Mouse       Desc.Sys        GDT.Ints, Ints.IRQ12, IDT.Int     ; Int 2Ch
IDT.IRQ13       Desc.Sys        GDT.Ints, Ints.IRQ13, IDT.Int     ; Int 2Dh
IDT.IDE0        Desc.Sys        GDT.Ints, Ints.IRQ14, IDT.Int     ; Int 2Eh
IDT.IDE1        Desc.Sys        GDT.Ints, Ints.IRQ15, IDT.Int     ; Int 2Fh
 
IDT.Halt        Desc.Sys        GDT.Ints, Ints.Halt, IDT.User     ; Int 30h
IDT.Yield       Desc.Sys        GDT.Ints, Ints.Yield, IDT.User    ; Int 31h