protect.seg

操作系统实验教程核心技术与编程实例书中地例子代码

TOS_STACKSEG    SEGMENT PARA USE16     
TOS_STACKLEN    = 4096
                DB TOS_STACKLEN DUP(0)
TOS_STACKSEG    ENDS
USER_P_STACKSEG SEGMENT PARA USE16     
USER_P_STACKLEN = 1024
                DB USER_P_STACKLEN DUP(0)
USER_P_STACKSEG ENDS

USER_P1_STACKSEG SEGMENT PARA USE16     
USER_P1_STACKLEN = 1024
                DB USER_P1_STACKLEN DUP(0)
USER_P1_STACKSEG ENDS
USER_P1_STACK0SEG SEGMENT PARA USE16     
USER_P1_STACK0LEN = 1024
                DB USER_P1_STACK0LEN DUP(0)
USER_P1_STACK0SEG ENDS

TOS_TSSSEG  SEGMENT PARA USE16
TOS_TASK    TASKSS <>
            DB 0FFH
TOS_TSSLEN  = $
TOS_TSSSEG  ENDS
USER_PsTSSSEG SEGMENT PARA USE16 
USER_Ps_TASK  TASKSS <>
            DB 0FFH
USER_PsTSSLEN = $ 
USER_PsTSSSEG  ENDS     

USER_P1TSSSEG SEGMENT PARA USE16 
             DD 0              ;LINK
             DD USER_P1_STACK0LEN,0              ;0_STACK
             DW USER_P1_STACK0_SEL,0
             DD 0              ;1_STACK
             DW ?,0
             DD 0              ;2_STACK
             DW ?,0
             DD 0 ;CR3
             DW USER_P1BEGIN,0 ;EIP
             DD 0 ;EFLAGS
             DD 0 ;EAX
             DD 0 ;ECX
             DD 0 ;EDX
             DD 0 ;EBX
             DD USER_P1_STACKLEN ;ESP
             DD 0 ;EBP
             DD 0 ;ESI
             DD 0 ;EDI
             DW G_VRAM_SEL,0 ;ES
             DW USER_P1_SEL,0       ;CS
             DW ?,0 ;USER_P1_STACK_SEL,0 ;SS
             DW ?,0 ;TOS_DATA_SEL,0      ;DS
             DW ?,0 ;USER_P1LDT_ASDATA_SEL,0 ;FS
             DW ?,0  ;GS
             DW USER_P1LDT_SEL,0
             DW 0
             DW $ + 2
             DB 0FFH
USER_P1TSSLEN = $ 
USER_P1TSSSEG  ENDS     

USER_PSEG   SEGMENT PARA USE16
            ASSUME CS:USER_PSEG,DS:DATA,SS:USER_P_STACKSEG
USER_PBEGIN:
            MOV AX,TOS_DATA_SEL
            MOV DS,AX

            ; disp 'A'
            MOV AX,G_VRAM_SEL
            MOV ES,AX
            MOV AH,24H;07 for white/black
            mov al,41h
            mov es:322,ax
            ; disp 'A'

            MOV AH,9
            MOV CX,0204H ;15 row 21 column
            MOV DX,OFFSET user_p_run
            INT 21H

            ; two segs_call
            MOV AX,04242H
            mov cx,0240H
            CALL16 tos_code_sel,disp_ext_ax

            cli
            MOV AX,REAL_SEL
            MOV ES,AX
            MOV FS,AX
            MOV GS,AX
            MOV SS,AX
            MOV DS,AX

            MOV EAX,CR0
            AND EAX,0FFFFFFFEH
            MOV CR0,EAX
            DB 0EAH
            DW OFFSET PROTECT_RET
            DW CODE
USER_PLEN   = $ 
USER_PSEG   ENDS

USER_P1SEG   SEGMENT PARA USE16
            ASSUME CS:USER_P1SEG ;,DS:DATA ;,SS:USER_P1_STACKSEG
USER_P1BEGIN:
;jmp USER_P1_end

            ;MOV AX,TOS_DATA_SEL
            ;MOV DS,AX

            ; disp 'A'
            MOV AX,G_VRAM_SEL
            MOV ES,AX
            MOV AH,24H;07 for white/black
            mov al,48h
            mov es:3040,ax
            ; disp 'A'

jmp USER_P1_end

            MOV AH,9
            MOV CX,0204H ;15 row 21 column
            MOV DX,OFFSET user_p_run
            INT 21H

            ; two segs_call
            MOV AX,04242H
            mov cx,0240H
            CALL16 tos_code_sel,disp_ext_ax
USER_P1_end:
            DB 0EAH
            DW 0  ;OFFSET PROTECT_RET
            DW p1_to_tos_sel

            cli
            MOV AX,REAL_SEL
            MOV ES,AX
            MOV FS,AX
            MOV GS,AX
            MOV SS,AX
            MOV DS,AX

            MOV EAX,CR0
            AND EAX,0FFFFFFFEH
            MOV CR0,EAX
            DB 0EAH
            DW 0  ;OFFSET PROTECT_RET
            DW p1_to_tos_sel
USER_P1LEN   = $ 
USER_P1SEG   ENDS