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INS1ST.ASM
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Assembly Source File
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1992-03-09
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4KB
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146 lines
; Need to include "lists.a" in order to get list structure definition.
include lists.a
extrn sl_malloc:far
wp equ <word ptr> ;I'm a lazy typist
; Special case to handle MASM 6.0 vs. all other assemblers:
; If not MASM 5.1 or MASM 6.0, set the version to 5.00:
ifndef @version
@version equ 500
endif
StdGrp group stdlib,stddata
stddata segment para public 'sldata'
stddata ends
stdlib segment para public 'slcode'
assume cs:stdgrp
; sl_Insert1st - DX:SI points at a list node.
; ES:DI points at a list.
; Insert the node at the beginning of the list
;
; Randall Hyde 3/4/92
;
public sl_Insert1st
sl_Insert1st proc far
push ds
push es
push di
if @version ge 600
; MASM 6.0 version goes here
mov word ptr es:[di].List.CurrentNode, si
mov word ptr es:[di+2].List.CurrentNode, dx
mov ds, dx
cmp wp es:[di].List.Head+2, 0 ;Empty list?
jne HasAList
; At this point, the HEAD pointer is zero. This only occurs if the
; list is empty. So point the Head and Tail pointers to the new node.
; Note: Technically, the NIL pointer is 32-bits of zero. However, this
; package assumes that if the segment is zero, the whole thing is zero.
; So don't put any nodes into segment zero!
mov wp es:[di].List.Head, si
mov wp es:[di].List.Head+2, dx
mov wp es:[di].List.Tail, si
mov wp es:[di].List.Tail+2, dx
mov wp ds:[si].Node.Next, 0 ;Set all the links
mov wp ds:[si].Node.Next+2, 0 ; in the first node
mov wp ds:[si].Node.Prev, 0 ; to NIL.
mov wp ds:[si].Node.Prev+2, 0
pop di
pop es
pop ds
jmp InsertDone
; If the HEAD pointer is non-NIL, insert the new node at the start of the
; list down here.
HasAList: les di, es:[di].List.Head ;Get ptr to beginning
mov wp es:[di].Node.Prev, si ;Insert current node
mov wp es:[di].Node.Prev+2, dx ; at start of list.
mov wp ds:[si].Node.Next, di ;Link in back ptr.
mov wp ds:[si].Node.Next+2, es
mov wp ds:[si].Node.Prev, 0 ;Set PREV field of
mov wp ds:[si].Node.Prev+2, 0 ; to NIL.
pop di ;Return ptr to list
pop es ; variable.
mov wp es:[di].List.Head, si ;Update last ptr.
mov wp es:[di].List.Head+2, dx
pop ds
else
; All other assemblers come down here:
mov word ptr es:[di].CurrentNode, si
mov word ptr es:[di+2].CurrentNode, dx
mov ds, dx
cmp wp es:[di].Head+2, 0 ;Empty list?
jne HasAList
; At this point, the HEAD pointer is zero. This only occurs if the
; list is empty. So point the Head and Tail pointers to the new node.
; Note: Technically, the NIL pointer is 32-bits of zero. However, this
; package assumes that if the segment is zero, the whole thing is zero.
; So don't put any nodes into segment zero!
mov wp es:[di].Head, si
mov wp es:[di].Head+2, dx
mov wp es:[di].Tail, si
mov wp es:[di].Tail+2, dx
mov wp ds:[si].Next, 0 ;Set all the links
mov wp ds:[si].Next+2, 0 ; in the first node
mov wp ds:[si].Prev, 0 ; to NIL.
mov wp ds:[si].Prev+2, 0
pop di
pop es
pop ds
jmp InsertDone
; If the HEAD pointer is non-NIL, insert the new node at the beginning of the
; list down here.
HasAList: les di, es:[di].Head ;Get ptr to beginning
mov wp es:[di].Prev, si ;Insert current node
mov wp es:[di].Prev+2, dx ; at start of list.
mov wp ds:[si].Next, di ;Link in back ptr.
mov wp ds:[si].Next+2, es
mov wp ds:[si].Prev, 0 ;Set PREV field of
mov wp ds:[si].Prev+2, 0 ; to NIL.
pop di ;Return ptr to list
pop es ; variable.
mov wp es:[di].Head, si ;Update last ptr.
mov wp es:[di].Head+2, dx
pop ds
endif
InsertDone:
ret
sl_Insert1st endp
stdlib ends
end