Source code of Windows XP (NT5)
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; PAGE 80,132 .xall
; Revision History:; ; M003 - added A20OFF_FLAG for MS PASCAL 3.2 compatibility support; for DOS5.X running in HMA. ;; M004 - added bit definition SETSSSP for DOS_FLAG for supporting; exe files without stack segment. ; This is no longer needed as we modify SP only. Removing ; this equate. 9/26/90;; M009 - addded comments relating to mace mkeyrate ver 1.0 support ; with DOS in HMA.;; M025 - Added SWITCHES=/W for suppressing mandatory loading; of WINA20.386;; M027 - Support for copy protected apps. Defined bit 2 of DOS_FLAG;
TRUE EQU 0FFFFhFALSE EQU 0
Installed = TRUEIFNDEF DEBUG DEBUG = FALSEENDIF
include dbcs.swinclude dosmac.INCinclude VERSIONA.INCinclude VERSION.INC
BREAK <Control character definitions>
c_DEL EQU 7Fh ; ASCII rubout or delete previous charc_BS EQU 08h ; ^H ASCII backspacec_CR EQU 0Dh ; ^M ASCII carriage returnc_LF EQU 0Ah ; ^J ASCII linefeedc_ETB EQU 17h ; ^W ASCII end of transmissionc_NAK EQU 15h ; ^U ASCII negative acknowledgec_ETX EQU 03h ; ^C ASCII end of textc_HT EQU 09h ; ^I ASCII tab
BREAK <Read This and Weep>
include buffer.INC
BREAK <User stack inside of system call and SysVars>; Location of user registers relative user stack pointer
user_environ STRUCuser_AX DW ? ; 00 hex offsets touser_BX DW ? ; 02 facilitate debugginguser_CX DW ? ; 04user_DX DW ? ; 06user_SI DW ? ; 08user_DI DW ? ; 0Auser_BP DW ? ; 0Cuser_DS DW ? ; 0Euser_ES DW ? ; 10user_IP DW ? ; 12user_CS DW ? ; 14user_F DW ? ; 16user_environ ENDS
BREAK <Disk map>
; MSDOS partitions the disk into 4 sections:;; phys sector 0: +-------------------+; | | boot/reserved |; | +-------------------+; | | File allocation |; v | table(s) |; | (multiple copies |; | are kept) |; +-------------------+; | Directory |; +-------------------+; | File space |; +-------------------+; | Unaddressable |; | (to end of disk) |; +-------------------+;; All partition boundaries are sector boundaries. The size of the FAT is; adjusted to maximize the file space addressable.
include dirent.INC
BREAK <File allocation Table information>;; The File Allocation Table uses a 12-bit entry for each allocation unit on; the disk. These entries are packed, two for every three bytes. The contents; of entry number N is found by 1) multiplying N by 1.5; 2) adding the result; to the base address of the Allocation Table; 3) fetching the 16-bit word; at this address; 4) If N was odd (so that N*1.5 was not an integer), shift; the word right four bits; 5) mask to 12 bits (AND with 0FFF hex). Entry; number zero is used as an end-of-file trap in the OS and is passed to the; BIOS to help determine disk format. Entry 1 is reserved for future use.; The first available allocation unit is assigned entry number two, and even; though it is the first, is called cluster 2. Entries greater than 0FF8H; (12-bit fats) or 0FFF8H (16-bit fats) are end of file marks; entries of zero; are unallocated. Otherwise, the contents of a FAT entry is the number of; the next cluster in the file.;; Clusters with bad sectors are tagged with FF7H. Any non-zero number would; do because these clusters show as allocated, but are not part of any; allocation chain and thus will never be allocated to a file. A particular; number is selected so that disk checking programs know what to do (ie. a; cluster with entry FF7H which is not in a chain is not an error).
;** Character Type Flags;; These flags are used in a lookup table indexed by the character code.; They're used to quickly classify characters when parsing paths.; I think that these are only used to parse FCBs - jgl
FCHK equ 1 ; I think this means "normal name char, no chks needed" -jglFDELIM equ 2 ; is a delimiterFSPCHK equ 4 ; set if character is not a space or equivalentFFCB equ 8 ; is valid in an FCB
include error.INC
;** Bit definitions for DOS_FLAG;; Bit 0 - this is set when a $open call is made from $exec. This is used in; $open to indicate to the redirector that this open is being made; by an exec call.;; Bit 2;; M003, M027:;; The start up code of MS PASCAL 3.2 programs depend on the 1M address wrap ; if they load below 64K. This is a likely possiblity in DOS 5.x with DOS in; the HMA. By default DOS will turn A20 OFF before Xferring control to the; user program in the case of an Exec call. The next call to DOS will turn; A20 line ON. It has been observed that MS PASCAL 3.2 start up does an int; 21 ah=25h call before executing the faulty code. This will turn A20 On. ; In order to support this we will set Bit 2 of this flag in the DOS exec; call (msproc.asm) if DOS is running in the HMA. In $set_interrupt_vector in; getset.asm A20OFF_COUNT is set to 1 if bit 2 of DOS_FLAG was previously set ; by a call to exec and if A20OFF_COUNT is 0. In msdisp.asm, if A20OFF_COUNT ; is non zero then A20 will be turned OFF before returning to the user. ; Bit 2 will be unconditionally cleared here.;; M009, M027:;; Mace utilities MKEYRATE.COM version 1.0 copyright 1987 is an execpacked ; program converted to a com file. Therefore if DOS is loaded high and if ; this program is loaded below 64K it will blurt out "packed file is corrupt".; This program does an int 21 ah=49h before executing the buggy execpacked; code. This int21 call turns a20 on and hence the problem. In $dealloc; alloc.asm A20OFF_COUNT is set to 1 if bit 2 of DOS_FLAG was previously set ; by a call to exec and if A20OFF_COUNT is 0. In msdisp.asm, if A20OFF_COUNT ; is non zero then A20 will be turned OFF before returning to the user. ; Bit 2 will be unconditionally cleared here.;;;
EXECOPEN EQU 00000001b ; bit 0 of DOS_FLAGSUPPRESS_WINA20 EQU 00000010b ; M025EXECA20OFF EQU 00000100b ; bit 2 of DOS_FLAG
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