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![Aleksandar Andrejevic](/assets/img/avatar_default.png)
Clean up the code and properly separate different modules into different files. svn path=/branches/ntvdm/; revision=59344
206 lines
5.4 KiB
C
206 lines
5.4 KiB
C
/*
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* COPYRIGHT: GPL - See COPYING in the top level directory
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* PROJECT: ReactOS Virtual DOS Machine
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* FILE: pic.c
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* PURPOSE: Programmable Interrupt Controller emulation
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* PROGRAMMERS: Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
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*/
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/* INCLUDES *******************************************************************/
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#include "pic.h"
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#include "emulator.h"
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/* PRIVATE VARIABLES **********************************************************/
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static PIC MasterPic, SlavePic;
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/* PUBLIC FUNCTIONS ***********************************************************/
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BYTE PicReadCommand(BYTE Port)
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{
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PPIC Pic;
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/* Which PIC are we accessing? */
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if (Port == PIC_MASTER_CMD) Pic = &MasterPic;
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else Pic = &SlavePic;
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if (Pic->ReadIsr)
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{
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/* Read the in-service register */
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Pic->ReadIsr = FALSE;
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return Pic->InServiceRegister;
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}
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else
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{
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/* The IRR is always 0, as the emulated CPU receives the interrupt instantly */
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return 0;
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}
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}
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VOID PicWriteCommand(BYTE Port, BYTE Value)
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{
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PPIC Pic;
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/* Which PIC are we accessing? */
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if (Port == PIC_MASTER_CMD) Pic = &MasterPic;
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else Pic = &SlavePic;
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if (Value & PIC_ICW1)
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{
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/* Start initialization */
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Pic->Initialization = TRUE;
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Pic->IntOffset = 0xFF;
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Pic->CascadeRegisterSet = FALSE;
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Pic->ConfigRegister = Value;
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return;
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}
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if (Value & PIC_OCW3)
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{
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/* This is an OCR3 */
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if (Value == PIC_OCW3_READ_ISR)
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{
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/* Return the ISR on next read from command port */
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Pic->ReadIsr = TRUE;
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}
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return;
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}
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/* This is an OCW2 */
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if (Value & PIC_OCW2_EOI)
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{
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if (Value & PIC_OCW2_SL)
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{
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/* If the SL bit is set, clear a specific IRQ */
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Pic->InServiceRegister &= ~(1 << (Value & PIC_OCW2_NUM_MASK));
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}
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else
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{
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/* Otherwise, clear all of them */
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Pic->InServiceRegister = 0;
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}
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}
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}
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BYTE PicReadData(BYTE Port)
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{
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/* Read the mask register */
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if (Port == PIC_MASTER_DATA) return MasterPic.MaskRegister;
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else return SlavePic.MaskRegister;
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}
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VOID PicWriteData(BYTE Port, BYTE Value)
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{
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PPIC Pic;
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/* Which PIC are we accessing? */
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if (Port == PIC_MASTER_DATA) Pic = &MasterPic;
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else Pic = &SlavePic;
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/* Is the PIC ready? */
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if (!Pic->Initialization)
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{
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/* Yes, this is an OCW1 */
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Pic->MaskRegister = Value;
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return;
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}
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/* Has the interrupt offset been set? */
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if (Pic->IntOffset == 0xFF)
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{
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/* This is an ICW2, set the offset (last three bits always zero) */
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Pic->IntOffset = Value & 0xF8;
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/* Check if we are in single mode and don't need an ICW4 */
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if ((Pic->ConfigRegister & PIC_ICW1_SINGLE)
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&& !(Pic->ConfigRegister & PIC_ICW1_ICW4))
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{
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/* Yes, done initializing */
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Pic->Initialization = FALSE;
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}
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return;
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}
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/* Check if we are in cascade mode and the cascade register was not set */
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if (!(Pic->ConfigRegister & PIC_ICW1_SINGLE) && !Pic->CascadeRegisterSet)
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{
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/* This is an ICW3 */
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Pic->CascadeRegister = Value;
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Pic->CascadeRegisterSet = TRUE;
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/* Check if we need an ICW4 */
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if (!(Pic->ConfigRegister & PIC_ICW1_ICW4))
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{
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/* No, done initializing */
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Pic->Initialization = FALSE;
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}
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return;
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}
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/* This must be an ICW4, we will ignore the 8086 bit (assume always set) */
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if (Value & PIC_ICW4_AEOI)
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{
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/* Use automatic end-of-interrupt */
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Pic->AutoEoi = TRUE;
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}
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/* Done initializing */
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Pic->Initialization = FALSE;
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}
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VOID PicInterruptRequest(BYTE Number)
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{
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BYTE i;
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if (Number >= 0 && Number < 8)
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{
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/* Check if any of the higher-priorirty interrupts are busy */
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for (i = 0; i <= Number ; i++)
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{
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if (MasterPic.InServiceRegister & (1 << Number)) return;
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}
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/* Check if the interrupt is masked */
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if (MasterPic.MaskRegister & (1 << Number)) return;
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/* Set the appropriate bit in the ISR and interrupt the CPU */
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if (!MasterPic.AutoEoi) MasterPic.InServiceRegister |= 1 << Number;
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EmulatorExternalInterrupt(MasterPic.IntOffset + Number);
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}
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else if (Number >= 8 && Number < 16)
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{
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Number -= 8;
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/*
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* The slave PIC is connected to IRQ 2, always! If the master PIC
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* was misconfigured, don't do anything.
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*/
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if (!(MasterPic.CascadeRegister & (1 << 2))
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|| SlavePic.CascadeRegister != 2)
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{
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return;
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}
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/* Check if any of the higher-priorirty interrupts are busy */
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if (MasterPic.InServiceRegister != 0) return;
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for (i = 0; i <= Number ; i++)
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{
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if (SlavePic.InServiceRegister & (1 << Number)) return;
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}
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/* Check if the interrupt is masked */
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if (SlavePic.MaskRegister & (1 << Number)) return;
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/* Set the IRQ 2 bit in the master ISR */
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if (!MasterPic.AutoEoi) MasterPic.InServiceRegister |= 1 << 2;
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/* Set the appropriate bit in the ISR and interrupt the CPU */
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if (!SlavePic.AutoEoi) SlavePic.InServiceRegister |= 1 << Number;
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EmulatorExternalInterrupt(SlavePic.IntOffset + Number);
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}
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}
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/* EOF */
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