71 lines
2.6 KiB
PHP
71 lines
2.6 KiB
PHP
BREAK <Int 2A Definitions>
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;** Int 2A functions
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;
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; Int 2A is an interface to the network code; it's also overloaded
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; as a critical section handler since critical sections
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; were originally created to support the net.
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;** This table was created by examining the source and may not be
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; complete or completely accurate - JGL
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;
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; M010 MD 8/31/90 - Added definition for AH = 5
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; (ah) = 0 installation check
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; (returns ah !=0 if installed)
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; (ah) = 1 cooked net bios call
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; (ah) = 3 query drive shared
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; (ds:si) = "n:" asciz string
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; (ah) = 4 net bios
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; (al) = 0 cooked net bios call
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; (al) = 1 raw net bios call
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; (al) = 2 ???
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;
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; (ah) = 5 Get Net Adaptor Resources. CX returns the number of
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; NCBs available/outstanding. DX returns the number of
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; sessions. Supposedly, this is documented in an old
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; IBM PC-LAN reference. Lotus Notes uses it. DOS LAN
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; Manager 2.0 Enhanced responds to it. But it should
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; not be used, as it is a hack, only to get Lotus
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; Notes running.
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;
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; (ah) = 80h enter critical section
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; (ah) = 81h leave critical section
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; (ah) = 82h free all critical sections (Leave-all)
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; (ah) = 84h entering idle loop (don't understand how this works)
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Break <Critical sections>
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;** Critical section definitions
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;
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; Although DOS is not designed to be reentrant there are some hacks
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; which various programs use to make it so, in a limited fashion.
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; Both WIN386 and some servers block copy a section of the DOS data
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; area so that DOS can be reentered on behalf of another thread/program.
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; DOS's global data structures, such as the memory arena, are not
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; in this area, so critical section indicators are used to protect
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; those areas. DOS flags a critical section by issuing an INT_IBM
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; (int 2Ah) at each critical section entry and exit. Some clients
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; (such as WIN386) just don't "context switch" the DOS when one
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; of these is in effect, others, such as the IBM server, go ahead
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; and reenter the DOS and if they get an int 2A to reenter the same
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; critical section they then switch away from that second thread and
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; let the first one finish and exit the section.
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;
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; These below are subject to leave-all sections
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critDisk EQU 1 ; Disk I/O critical section
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critShare EQU 1 ; Sharer I/O critical section
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critMem EQU 1 ; memory maintenance critical section
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critSFT EQU 1 ; sft table allocation
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critDevice EQU 2 ; Device I/O critical section
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critNet EQU 5 ; network critical section
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critIFS EQU 6 ; ifsfunc critical section
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; These below are not subject to leave-all sections
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critASSIGN EQU 8 ; Assign has munged a system call
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