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Assembly Source File | 1993-05-04 | 9.9 KB | 589 lines

; ; TCP/IP support routines ;**************************************************************************** ;* * ;* * ;* part of NCSA Telnet * ;* by Tim Krauskopf, VT100 by Gaige Paulsen, Tek by Aaron Contorer * ;* * ;* National Center for Supercomputing Applications * ;* 152 Computing Applications Building * ;* 605 E. Springfield Ave. * ;* Champaign, IL 61820 * ;* * ;**************************************************************************** ; NAME ASMSTUFF include model.inc ifdef Microsoft DGROUP group _DATA _DATA segment public 'DATA' assume DS:DGROUP .DATA else DSEG endif ifdef Microsoft _DATA ends _TEXT segment public 'CODE' assume CS:_TEXT PUBLIC _IPCHECK, _TCPCHECK, _LONGSWAP, _INTSWAP, _DBG, _N_PUTCHAR PUBLIC _SEGSS, _SEGDS, _SEGCS PUBLIC _DOS_EXIT PUBLIC _N_KBHIT, _N_GETCH PUBLIC _N_LMUL PUBLIC _N_LDIV PUBLIC _N_LMOVE PUBLIC _N_MAMOUNT PUBLIC _FAR2LONG PUBLIC _CANNON PUBLIC _LONG2FAR else ENDDS PSEG PUBLIC IPCHECK,TCPCHECK,LONGSWAP,INTSWAP,DBG,N_PUTCHAR PUBLIC SEGSS, SEGDS, SEGCS PUBLIC DOS_EXIT PUBLIC N_KBHIT, N_GETCH PUBLIC N_LMUL PUBLIC N_LDIV PUBLIC N_LMOVE PUBLIC N_MAMOUNT PUBLIC FAR2LONG PUBLIC CANNON PUBLIC LONG2FAR endif ; ; Routines for general use by the communications programs ; ; ;************************************************************************ ; DBG ; provides a synch point for debugging ; START_PROC dbg nop nop nop ret END_PROC dbg ; ;************************************************************************* ; Internet header checksum ; header checksum is calculated for a higher level program to verify ; ; USAGE: ipcheck((IPKT *)ptr,(int)len) ; ; this proc knows that the IP header length is found in the first byte ; START_PROC IPCHECK PUSH BP MOV BP,SP PUSH ES PUSH SI PUSH DI MOV SI,[BP+X] ; pointer to data MOV CX,[BP+X+2] ; count of words to test XOR BX,BX CLC CHKSUM: LODSW ; get next word ADC BX,AX ; keep adding LOOP CHKSUM ; til' done ADC BX,0 ; adds the carry bit in ; NOT BX ; take one more 1-complement MOV AX,BX POP DI POP SI POP ES POP BP RET END_PROC IPCHECK ; ; TCP checksum, has two parts, including support for a pseudo-header ; ; usage: tcpcheck(psptr,tcpptr,tcplen) ; char *psptr,*tcpptr; pointers to pseudo header and real header ; int tcplen length of tcp packet in checksum ; START_PROC TCPCHECK PUSH BP MOV BP,SP PUSH SI PUSH DI MOV SI,[BP+X] ; pointer to data MOV CX,6 ; length of p-hdr in words XOR BX,BX ; clear to begin CLC PCHKSUM: LODSW ; get next word ADC BX,AX ; keep adding LOOP PCHKSUM ; til' done ADC BX,0 ; adds the carry bit in ; ; NOW THE REAL THING ; MOV SI,[BP+X+2] ; pointer MOV CX,[BP+X+4] ; count of bytes to test MOV DX,CX ; keep a copy SHR CX,1 ; divide by two, round down CLC RCHKSUM: LODSW ADC BX,AX ; add to previous running sum LOOP RCHKSUM ADC BX,0 ; add the last carry in again AND DX,1 ; odd # of bytes? JZ NOTODD LODSB ; get that last byte XOR AH,AH ; clear the high portion ADD BX,AX ; add the last one in ADC BX,0 ; add the carry in, too NOTODD: NOT BX ; take one more 1-complement MOV AX,BX POP DI POP SI POP BP RET END_PROC TCPCHECK ; ;************************************************************************* ; longswap ; swap the bytes of a long integer from PC ; order (reverse) to in-order. This will work both ways. ; returns the new long value ; usage: ; l2 = longswap(l) ; long l; ; ifdef Microsoft _LONGSWAP PROC NEAR PUSH BP MOV BP,SP MOV AX,[BP+X+2] ; HIGH BYTES OF THE LONG INT MOV DX,[BP+X] ; LOW BYTES OF THE LONG INT ; ; GET THE DATA ; XCHG AH,AL ; SWAP THEM, THESE ARE NOW LOW XCHG DH,DL ; SWAP THE OTHERS POP BP RET _LONGSWAP ENDP else LONGSWAP PROC NEAR PUSH BP MOV BP,SP MOV BX,[BP+X+2] ; HIGH BYTES OF THE LONG INT MOV AX,[BP+X] ; LOW BYTES OF THE LONG INT ; ; GET THE DATA ; XCHG AH,AL ; SWAP THEM, THESE ARE NOW LOW XCHG BH,BL ; SWAP THE OTHERS POP BP RET LONGSWAP ENDP endif ; ;************************************************************************* ; INTSWAP ; swap the bytes of an integer, returns the swapped integer ; ; usage: i = intswap(i); ; START_PROC INTSWAP PUSH BP MOV BP,SP MOV AX,[BP+X] XCHG AH,AL POP BP RET END_PROC INTSWAP ; ; Support for BIOS calls in NCSA Telnet ; ; From original code by Tim Krauskopf 1984-1985 ; ; Modified and ported to Lattice C, Sept. 1986 ; ifdefs for Microsoft C, June 1987 ; Tim Krauskopf ; ; Modified for version 2.3 release May 1990 by Heeren Pathak ; ; National Center for Supercomputing Applications ; ; The subroutines to call from C ; ;/***************************************************************/ ; n_putchar(letter) ; puts onto screen at current cursOR location ; START_PROC N_PUTCHAR PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI MOV AL,[BP+X] ; char to write MOV BL,3 ; SEND WHATEVER CHAR MOV BH,0 MOV AH,14 INT 10H POP DI POP SI POP ES POP DS POP BP RET END_PROC N_PUTCHAR START_PROC SEGSS mov ax,ss ret END_PROC SEGSS START_PROC SEGCS mov ax,cs ret END_PROC SEGCS START_PROC SEGDS mov ax,ds ret END_PROC SEGDS START_PROC dos_exit ; assume dos version 2 PUSH BP MOV BP,SP MOV AL,[BP+X] ; exit code mov ah, 4ch int 21h pop bp ; shouldn't get here ret END_PROC dos_exit START_PROC n_kbhit PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI MOV AH,1 INT 16H mov ax,0 jz not_there inc ax not_there: POP DI POP SI POP ES POP DS POP BP RET END_PROC n_kbhit START_PROC n_getch PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI MOV AH,0 INT 16H cmp al,0 jz special xor ah,ah special: POP DI POP SI POP ES POP DS POP BP RET END_PROC n_getch START_PROC N_LMUL PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI mov ax,[x+bp] mov dx,[x+bp+2] ; high mov bx,[x+bp+4] ; low mov cx,[x+bp+6] ; high mov bp,dx ; if both high words zero - great or bp,cx jnz star1 mul bx jmp mul_exit star1: mov bp,ax push dx mul bx xchg ax,bp xchg cx,dx mul dx add cx,ax pop ax mul bx add cx,ax mov dx,cx ; high mov ax,bp ; low mul_exit: POP DI POP SI POP ES POP DS POP BP RET END_PROC N_LMUL ; expects (long divisor) (long dividend) returns dx:ax ISOR_HIGH EQU (X+6) ISOR_LOW EQU (X+4) DEND_HIGH EQU (X+2) DEND_LOW EQU (X) ; START_PROC N_LDIV push bp mov bp,sp push di push si push bx xor di,di mov ax,[bp+DEND_HIGH] or ax,ax jge dvs_1 inc di mov dx,[bp+DEND_LOW] neg ax neg dx sbb ax,0 mov [bp+DEND_HIGH],ax mov [bp+DEND_LOW],dx dvs_1: mov ax,[bp+ISOR_HIGH] or ax,ax jge dvs_2 inc di mov dx,[bp+ISOR_LOW] neg ax neg dx sbb ax,0 mov [bp+ISOR_HIGH],ax mov [bp+ISOR_LOW],dx dvs_2: or ax,ax jnz dvs_3 mov cx,[bp+ISOR_LOW] mov ax,[bp+DEND_HIGH] xor dx,dx div cx mov bx,ax mov ax,[bp+DEND_LOW] div cx mov dx,bx jmp dvs_4 dvs_3: mov bx,ax mov cx,[bp+ISOR_LOW] mov dx,[bp+DEND_LOW] mov ax,[bp+DEND_HIGH] dvs_5: shr bx,1 rcr cx,1 shr dx,1 rcr ax,1 or bx,bx jnz dvs_5 div cx mov si,ax mul word ptr [bp+ISOR_HIGH] xchg cx,ax mov ax,[bp+ISOR_LOW] mul si add dx,cx jb dvs_6 cmp dx,[bp+DEND_HIGH] ja dvs_6 jb dvs_7 cmp ax,[bp+DEND_LOW] jbe dvs_7 dvs_6: dec si dvs_7: xor dx,dx xchg si,ax dvs_4: dec di jnz dvs_8 neg dx neg ax sbb dx,0 dvs_8: pop bx pop si pop di mov sp,bp pop bp ret END_PROC N_LDIV START_PROC n_lmove PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI mov ax,ds mov es,ax ; copy ds mov si,[x+bp] ; pointer mov cx,[x+bp+2] ; no of words to move mov ax,8700h ; extended memory block move int 15h jc n_l_err xor ax,ax jmp n_l_out n_l_err: mov al,ah xor ah,ah n_l_out: POP DI POP SI POP ES POP DS POP BP RET END_PROC n_lmove START_PROC n_mamount PUSH BP MOV BP,SP PUSH DS PUSH ES PUSH SI PUSH DI mov ax,8800h ; extended memory amount int 15h POP DI POP SI POP ES POP DS POP BP RET END_PROC n_mamount START_PROC far2long PUSH BP MOV BP,SP mov dx,[x+2+bp] ; high xor ax,ax ; clear low for now mov cx,12 f2lp: shr dx,1 ; shift low bit into carry rcr ax,1 ; carry into top bit loop f2lp add ax,[x+bp] ; low adc dx,0 POP BP RET END_PROC far2long START_PROC cannon PUSH BP MOV BP,SP mov dx,[x+2+bp] ; high mov ax,[x+bp] ; low mov cl,4 shr ax, cl add dx,ax ; this could overflow ; --- but not unless fxxxx + ffff mov ax,[x+bp] ; low and ax,0fh POP BP RET END_PROC cannon START_PROC long2far PUSH BP MOV BP,SP mov dx,[x+2+bp] ; high mov cl,4 shr dx,1 ; put into carry rcr dx,cl ; low 4 bits into high four bits and dx,0f000h mov ax,[x+bp] ; low mov cl,4 shr ax,cl ; divide by 16 add dx,ax ; could or mov ax,[x+bp] ; low again and ax,0fh POP BP RET END_PROC long2far ifdef Microsoft _TEXT ends else ENDPS endif END