80X86 MULTI-TASKING OPERATION SYSTEM: pic

00001 ;/*******************
00002 ;*Project: 80X86 32BIT MULTI TASKING OPERATING SYSTEM
00003 ;*Function: assembly part of driver for 8259 programable interrupt controller
00004 ;*
00005 ;*File: pic_a.asm
00006 ;*Author: Book Chen
00007 ;*Date: 2010.01.01
00008 ;********************
00009 ;*/
00010 
00011 %define PIC_MASTER_PORT    0x20 ;master 8259
00012 %define PIC_MASTER_PORT2   0x21 ;master 8259
00013 %define PIC_SLAVE_PORT     0xa0 ;slave 8259
00014 %define PIC_SLAVE_PORT2    0xa1 ;slave 8259
00015 %define PIC_EOI            0x20 ;end of interrupt
00016 
00017 global _PicIrqDisable
00018 global _PicIrqEnable
00019 
00020 [section .text]                  ;code section
00021 ;/****************************
00022 ;*function:_DisableIrq
00023 ;*description:Disable irq
00024 ;*****************************/
00025 _PicIrqDisable:
00026     mov ecx,[esp+4]         ;get paramter passed
00027     pushfd
00028     cli                     ;disable all maskable interrupt
00029     mov ah,1                ;ah=1
00030     rol ah,cl               ;
00031     cmp cl,8
00032     jae L_DisableHighIrq    ;if >=8,jump to disable high irq
00033 L_DisableLowIrq:    
00034     in al,PIC_MASTER_PORT2  ;get current master pic setting
00035     or al,ah                ;set ith bit in pic master
00036     out PIC_MASTER_PORT2,al ;write to 8259
00037     popfd                    ;pop register back
00038     ret                     ;return
00039 L_DisableHighIrq:
00040     in al,PIC_SLAVE_PORT2   ;get current master pic setting
00041     or al,ah                ;set ith bit in pic master
00042     out PIC_SLAVE_PORT2,al  ;write to 8259
00043     popfd                    ;pop register back
00044     ret                     ;return
00045 ;/****************************
00046 ;*function:_EnableIrq
00047 ;*description:Enable irq
00048 ;*****************************/
00049 _PicIrqEnable:
00050     mov ecx,[esp+4]         ;get irq number
00051     pushfd                  ;push eflags of cpu
00052     cli                     ;disable external interrupt
00053     mov ah,~1               ;ah=11111110b
00054     rol ah,cl               ;shift 0's bit to corrospand
00055     cmp cl,8                ;compare cl with 8
00056     jae L_EnableHighIrq     ;if cl >= 8,jump EnableHighIrq
00057 L_EnableLowIrq:
00058     in  al,PIC_MASTER_PORT2 ;unmask int bit in master 8259 
00059     and al,ah               ;unmask int bit in master 8259 
00060     out PIC_MASTER_PORT2,al ;unmask int bit in master 8259 
00061     popfd                   ;pop eflags of cpu
00062     ret
00063 L_EnableHighIrq:    
00064     in al,PIC_SLAVE_PORT2   ;unmask int bit in slave 8259 
00065     and al,ah               ;unmask int bit in slave 8259 
00066     out PIC_SLAVE_PORT2,al  ;unmask int bit in slave 8259 
00067     popfd                   ;pop eflags of cpu
00068     ret