168 lines
4 KiB
NASM
168 lines
4 KiB
NASM
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; spcemm.asm,
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;
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; 10-Dec-1992 Jonle , adapted from em_drvr.asm from Insignia solutions
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;
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; This code serves as a stub device driver for emm memory manager.
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; Its sole purpose is for apps to be able to identify that an emm driver is
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; loaded and that LIM services are available. This code is linked into the
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; device driver chain contains a strategy, interrupt and device header
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;
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; The driver should only be loaded if emm memory is available
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; from NTVDM.
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;
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BOP MACRO callid
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db 0c4h, 0c4h, callid
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endm
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;
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; Request Header, for initialization
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;
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REQHEAD STRUC
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ReqLen DB ? ; Length in bytes of request block
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ReqUnit DB ? ; Block Device unit number
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ReqFunc DB ? ; Type of request
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ReqStat DW ? ; Status Word
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REQHEAD ENDS
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;
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; Segment definitions for ntio.sys,
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;
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include biosseg.inc
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include vint.inc
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SpcEmmSeg segment
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assume cs:SpcEmmSeg,ds:nothing,es:nothing
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;
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; SpcEmmBeg - SpcEmmEnd
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;
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; Marks the resident code, anything outside of these markers
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; is discarded after intialization
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; 11-Dec-1992 Jonle
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;
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public SpcEmmBeg
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SpcEmmBeg label byte
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;
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; character device Header
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; must be first in the .sys file
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;
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dd -1 ;pointer to next device driver
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dw 8000H ;attribute (plain character device)
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dw offset STRATEGY ;pointer to device "strategy" routine
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dw offset Interrupt ;pointer to device "interrupt" routine
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db 'EMMXXXX0' ;8 byte name DO NOT CHANGE THE NAME
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;
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; Request Header address, saved here by strategy routine
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;
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pReqHdr dd ?
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;
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; Device "strategy" entry point, save request header address
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;
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Strategy proc far
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mov word ptr cs:pReqHdr, bx
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mov word ptr cs:pReqHdr+2, es
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ret
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Strategy endp
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; EmmIsr - int 67h isr
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;
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EmmIsr: ; LIM Isr
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bop 67h
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emmiret:
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FIRET
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; ret trap for em function 'alter page map & call'
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EmmRet:
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bop 68h
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jmp emmiret
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;----------------------------------------------------------------------
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; Device "interrupt" entry point
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;----------------------------------------------------------------------
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Interrupt PROC FAR
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push es
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push di
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les di, cs:pReqHdr ; check for valid commands
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cmp es:[di.ReqFunc], 0ah
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je validcmd
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cmp es:[di.ReqFunc], 0
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je validcmd
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mov ax, 8003h ; we don't handle anything else
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jmp short irptexit
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validcmd:
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xor ax,ax
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irptexit:
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or ax, 0100h ;tell em we finished
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mov es:[di.ReqStat],AX ;store status in request header
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pop di
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pop es
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ret
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Interrupt ENDP
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public SpcEmmEnd
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SpcEmmEnd label byte
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public InitSpcEmm
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;
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; InitSpcEmm Initializes Spc 32 bit memory manager
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; returns ax=0 for success
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;
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; Inputs: ds is expected seg for drv code, cs is temporary sysinitseg
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; Outputs: ax zero for success
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;
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InitSpcEmm proc near
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; BOP 66 - initialize LIM memory
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; pass the address of bop 68 to the em manager
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; in ds:dx and to return the number of em pages in BX
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;
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; NOTE: All EMM options come from pif file
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; There are NO command line options
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xor bx, bx
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mov dx, offset EmmRet
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bop 66h
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cmp bx, 0ffffh ;ffff means incorrect config (eg no 64K gap)
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je fail
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cmp bx, 0 ;check expanded memory is available
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je fail
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; set up IVT for INT 67h
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FCLI
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xor ax, ax
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mov es, ax
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mov bx, offset EmmIsr
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mov word ptr es:[67h*4], bx
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mov word ptr es:[(67h*4)+2], ds
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FSTI
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ret
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fail:
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mov ax, 0ffffh
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ret
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InitSpcEmm endp
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SpcEmmSeg ends
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end
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