Assembly
Determines the type of UART in each serial port
Determines the type of UART in each serial port comment * SERTYPE.ASM Purpose: Determines the type of UART in each serial port * 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 ;DS := _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 ;point to modem ctrl reg in al, dx ;disable interrupts push ax and al, 11111011b out dx, al mov ch, 0 ;assume type 0 mov dx, bx add dx, 7 ;see 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 ;point 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 ;point 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 ;point 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 message 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
Determines the type of UART in each serial port
