Assembly Source series of Sertype

This is the past DOS era of the compilation of source code, although has passed, but for the study of the assembly is still helpful, assembly language is just a basic programmer language, most people can grasp, not necessarily in-depth research.

Comment *
Sertype. Asm
Purpose:
Determines the type of UART in each serial port
Author:
Douglas Boling, in PCMag. With some modifications by Yousuf Khan.
*
Dosseg
BDSEG segment at 40h; BIOS data segment
COM1 DW?
COM2 DW?
COM3 DW?
COM4 DW?
Ends
_DATA segment para ' data '
Uart1 DB 0
Uart2 DB 0
UART3 DB 0
UART4 DB 0
Portmsg db "COMx: $"
x8250 db "NS 8250 (Non-fifo)", 13, 10, "$"
x16450 db "NS 8250a/16450/16550 (Non-fifo)", 13, 10, "$"
Xfifo db "NS 16550a/intel 82510 (FIFO)", 13, 10, "$"
XDMA db "IBM Type 3 (FIFO/DMA)", 13, 10, "$"
Pas_de_ports DB "No serial ports Detected", 13, 10, "$"
Ends
_stack segment para stack ' stack '
DB 200h dup (?)
Ends
CSEG segment para ' code '
mov ax, bdseg
mov es, ax; es: = bdseg
mov ax, _data
mov ds, ax;D s: = _data
Assume Cs:cseg, Ds:_data, Es:bdseg, Ss:_stack
Xor Al, Al; # of serial ports = 0
MOV dx, [COM1]
CMP DX, 0
Je eoproc
Inc al; # of serial ports = 1
Push AX
Call Uartdet
mov [Uart1], AL; Remember the type of this UART
Pop ax
MOV dx, [COM2]
CMP DX, 0
Je eoproc
Inc al; # of serial ports = 2
Push AX
Call Uartdet
mov [Uart2], AL
Pop ax
MOV dx, [COM3]
CMP DX, 0
Je eoproc
Inc al; # of serial ports = 3
Push AX
Call Uartdet
mov [UART3], AL
Pop ax
MOV dx, [COM4]
CMP DX, 0
Je eoproc
Inc al; # of serial ports = 4
Push AX
Call Uartdet
mov [UART4], AL
Pop ax
Eoproc:
Call disp
mov ah, 4ch
int 21h
Delay macro
JMP $+2
Endm
Uartdet proc Near
Push BX
Push CX
mov bx, DX; save starting I/O addr
Add dx, 4;p oint to modem CTRL REG
In AL, DX;d isable interrupts
Push AX
And Al, 11111011b
Out DX, AL
mov ch, 0; assume type 0
MOV dx, bx
Add DX, 7; if scratch Reg exists
mov al, 55h
Cli
Out DX, Al; Write to scratch Reg
Delay
In AL, DX; Read back
CMP al, 55h
Jne Endudet
mov al, 0AAh
Out DX, Al; Write to scratch Reg
Delay
In AL, DX; Read back
STi
CMP al, 0AAh
Jne Endudet
Inc ch; Assume type 1
MOV dx, bx
Add dx, 2;p oint to FIFO CTRL reg
mov al, 7; Attempt to enable FIFOs
Cli
Out DX, AL
Delay
In AL, DX; Read Interrupt ID Reg
STi
And Al, 0c0h strip all but FIFO bits
JZ Endudet If bits 0, 16450/16550
Inc ch; Assume type 2
MOV dx, bx
Add dx, 8003h;p oint to enhanced Reg 1
Cli
In AL, DX
Push AX
Or AL, 01000000b; Enable DMA transmission
Out DX, AL
Push DX
MOV dx, bx
Add DX, 2
In AL, DX
MOV cl, AL
Pop dx; restore enhanced Reg 1
Pop ax
Out DX, AL
STi
and Cl, 0c0h again mask all but FIFO ID
CMP cl, 40h
Jne Endudet must be type 2 (FIFO)
Inc ch; must be Type 3 (DMA)
Endudet:
Pop ax
MOV dx, bx
Add dx, 4;p oint to modem CTRL REG
Out DX, AL; Restore initial condition
XOR ax, Ax
mov al, ch
MOV dx, bx
Pop CX
Pop bx
Ret
Uartdet ENDP
DISP proc Near
Push ax, save ax
CMP al, 0; no serial ports?
Je noports
mov bx, offset ds:[uart1]; offset of UART type field
mov di, offset ds:[portmsg][3]; offset of 4th Char in
MOV cx, 0
MOV cl, AL; Number of iterations
@l1:
;
; write ' COMx: ' Message substituting ' x ' for proper comport #
;
MOV dl, 4
Sub DL, CL
Add DL, 30h; Convert to ASCII number
mov [di], DL
Lea DX, portmsg
mov Ah, 9
int 21h
;
; write the UART type now
;
mov dl, [BX]
CMP DL, 0
Jne @t2
Lea DX, x8250
mov Ah, 9
int 21h
JMP @eot
@t2: CMP DL, 1
Jne @t3
Lea DX, x16450
mov Ah, 9
int 21h
JMP @eot
@t3: CMP DL, 2
Jne @t4
Lea DX, Xfifo
mov Ah, 9
int 21h
JMP @eot
@t4: Lea DX, XDMA
mov Ah, 9
int 21h
@eot: Inc BX
Loop @l1
JMP EOPROC2
Noports:
Lea DX, Pas_de_ports
mov Ah, 9
int 21h
EOPROC2:
Pop ax
Ret
Disp ENDP
Ends
End
; EOF Sertype. Asm