Source code of Windows XP (NT5)
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;\ ; obj.asm ; ; Copyright (C) 1992, MicroSoft Corporation ; ; Contains pointer validation routine ; ; History: sriniK 02/01/1991 original ; (8.20.91) v-dougk made into far proc ;/
.286p.MODEL MEDIUM.CODE
;**************************** _CheckPointer ****************************;; WORD _CheckPointer (lp, access);; Args:; lp pointer to be verified; access 0 test the pointer for read access; 1 test the pointer for write access; returns: ; FALSE invalid pointer; TRUE valid pointer;;; public _CheckPointer
_CheckPointer proc
push bp mov bp, sp xor ax, ax ; assume an error and word ptr [bp+0AH], -1 jnz check_write_access
verr word ptr [bp+8] ; check selector for read access jnz error jmp short check_offset
check_write_access: verw word ptr [bp+8] ; check selector for write access jnz error check_offset: lsl bx, word ptr [bp+8] ; segment limit gets copied into BX jnz error cmp [bp+6], bx ja error or ax, -1 error: pop bp ret
_CheckPointer endp
end
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