windows-nt/Source/XPSP1/NT/base/mvdm/dos/v86/inc/dossym.inc

178 lines
6 KiB
PHP
Raw Normal View History

2020-09-26 03:20:57 -05:00
; 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 0FFFFh
FALSE EQU 0
Installed = TRUE
IFNDEF DEBUG
DEBUG = FALSE
ENDIF
include dbcs.sw
include dosmac.INC
include VERSIONA.INC
include VERSION.INC
BREAK <Control character definitions>
c_DEL EQU 7Fh ; ASCII rubout or delete previous char
c_BS EQU 08h ; ^H ASCII backspace
c_CR EQU 0Dh ; ^M ASCII carriage return
c_LF EQU 0Ah ; ^J ASCII linefeed
c_ETB EQU 17h ; ^W ASCII end of transmission
c_NAK EQU 15h ; ^U ASCII negative acknowledge
c_ETX EQU 03h ; ^C ASCII end of text
c_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 STRUC
user_AX DW ? ; 00 hex offsets to
user_BX DW ? ; 02 facilitate debugging
user_CX DW ? ; 04
user_DX DW ? ; 06
user_SI DW ? ; 08
user_DI DW ? ; 0A
user_BP DW ? ; 0C
user_DS DW ? ; 0E
user_ES DW ? ; 10
user_IP DW ? ; 12
user_CS DW ? ; 14
user_F DW ? ; 16
user_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" -jgl
FDELIM equ 2 ; is a delimiter
FSPCHK equ 4 ; set if character is not a space or equivalent
FFCB 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_FLAG
SUPPRESS_WINA20 EQU 00000010b ; M025
EXECA20OFF EQU 00000100b ; bit 2 of DOS_FLAG