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Assembly Source File | 1993-07-12 | 15.1 KB | 746 lines

NAME MSNUT1 ; File MSNUT1.ASM ; Provides various Intel 8088 level operations, including ; display facilities (via msg buffer or DOS) for char, strings, etc. ; ; Copyright 1991, University of Waterloo. ; Copyright (C) 1985, 1993, Trustees of Columbia University in the ; City of New York. Permission is granted to any individual or institution ; to use this software as long as it is not sold for profit. This copyright ; notice must be retained. This software may not be included in commercial ; products without written permission of Columbia University. ; ; Written by Erick Engelke of the University of Waterloo, Waterloo, ; Ontario, Canada, ; and by Joe R. Doupnik, Utah State University, ; jrd@cc.usu.edu, jrd@usu.Bitnet. ; ; Edit history ; 27 August 1992 version 3.13 ; 6 Sept 1991 v3.11 ; Last Edit ; 13 May 1993 cr equ 0dh lf equ 0ah conout equ 2 dos equ 21h allocmem equ 48h freemem equ 49h MSGBUFLEN equ 512 ; coordinate with msntnd.c BIOSCLK equ 046ch HI_MAX equ 018h LO_MAX equ 0b0h _TEXT SEGMENT WORD PUBLIC 'CODE' _TEXT ENDS _DATA SEGMENT WORD PUBLIC 'DATA' _DATA ENDS CONST SEGMENT WORD PUBLIC 'CONST' CONST ENDS _BSS SEGMENT WORD PUBLIC 'BSS' _BSS ENDS DGROUP GROUP CONST, _BSS, _DATA ASSUME CS: _TEXT, DS: DGROUP, SS: DGROUP _DATA SEGMENT extrn _doslevel:word, _msgcnt:word, _msgbuf:byte,_display_mode:byte _DATA ENDS _TEXT segment ; Compute 1's-complement sum of data buffer ; unsigned checksum( unsigned word *buf, unsigned cnt) public _checksum _checksum proc near push bp mov bp,sp push si push bx push cx push dx mov si,[bp+4+0] ; offset of data to be checked mov cx,[bp+4+2] ; cx = cnt mov bl,cl shr cx,1 ; group into words xor dx,dx ; set checksum to 0 cld jcxz chk3 clc chk1: lodsw adc dx,ax loop chk1 ; resolve remainder chk2: adc dx,0 jc chk2 chk3: and bl,1 jz chk5 xor ah,ah lodsb clc add dx,ax chk4: adc dx,0 jc chk4 chk5: mov ax,dx ; result into ax or ax,ax jnz chk6 mov ax,0ffffh chk6: pop dx pop cx pop bx pop si pop bp ret _checksum endp ; ntohl(longword x) 32 bit network (big endian) to host (little endian) ; htonl(longword x) 32 bit host (little endian) to network (big endian) ; intel(longword x) ; Reverse order of 4 byte groups between big and little endian forms ; public _intel, _ntohl, _htonl _intel proc near _ntohl equ this byte _htonl equ this byte push bp mov bp,sp mov ax,[bp+4+2] mov dx,[bp+4+0] xchg al,ah xchg dl,dh pop bp ret _intel endp ; ntohs(word x) 16 bit network (big endian) to host (little endian) ; htons(word x) 16 bit host (little endian) to network (big endian) ; intel16(word x) ; Reverse order of 2 byte groups between big and little endian forms public _intel16, _ntohs, _htons _intel16 proc near _ntohs equ this byte _htons equ this byte push bp mov bp,sp mov ax,[bp+4+0] xchg al,ah pop bp ret _intel16 endp ; int ourmod(int top, int bottom) ; Perform modulo function on 16 bit quantities public _ourmod _ourmod proc near push bp mov bp,sp push bx mov ax,[bp+4+0] ; top number mov bx,[bp+4+2] ; bottom number (radix) xor dx,dx or bx,bx ; bottom is zero? jz ourmod1 ; z = yes, return zero div bx ourmod1:mov ax,dx ; return remainder pop bx pop bp ret _ourmod endp ; int ourdiv(int top, int bottom) ; Perform 16 bit integer division public _ourdiv _ourdiv proc near push bp mov bp,sp push bx mov ax,[bp+4+0] ; top mov bx,[bp+4+2] ; bottom xor dx,dx or bx,bx ; divide by zero? jz outdiv1 ; z = yes, divide by one div bx outdiv1:pop bx pop bp ; quotient is returned in ax ret _ourdiv endp ; int ourlmod(long top, int bottom) ; Perform 32 bit integer modulo function public _ourlmod _ourlmod proc near push bp mov bp,sp push bx mov ax,[bp+4+0] ; top lower 16 bits mov dx,[bp+4+2] ; top upper 16 bits mov bx,[bp+4+4] ; bottom or bx,bx ; zero? jz outlmo1 ; z = yes divide by 2^16 and quit div bx outlmo1:mov ax,dx ; return remainder in ax pop bx pop bp ret _ourlmod endp ; int ourldiv(long top, int bottom) ; Perform 32 bit integer division of 32 bit quotient by 16 bit divisor public _ourldiv _ourldiv proc near push bp mov bp,sp push bx mov ax,[bp+4+0] ; top lower 16 bits mov dx,[bp+4+2] ; top upper 16 bits mov bx,[bp+4+4] ; bottom cmp dx,bx ; about to overflow? jae ourldiv1 ; ae = yes, return 0xffffh div bx xor dx,dx ; clear remainder (high order ret) pop bx pop bp ; quotient is returned in dx:ax ret ourldiv1:mov ax,0ffffh ; overflow indication xor dx,dx ; clear high order pop bx pop bp ret _ourldiv endp ; long ourlmul(long top, int bottom) ; Perform 32 bit integer multiplication of 32 bit multiplicand by 16 bit mult public _ourlmul _ourlmul proc near push bp mov bp,sp push bx push cx mov ax,[bp+4+2] ; top upper 16 bits mov bx,[bp+4+4] ; bottom mul bx mov cx,ax ; save product (no overflow noted) mov ax,[bp+4+0] ; top lower 16 bits mul bx adc dx,cx ; new upper 16 bits pop cx pop bx mov sp,bp pop bp ; long product is returned in dx:ax ret _ourlmul endp ; void * bcopy(src, dest, count) ; void *dest, *src; ; size_t count; ; copy count bytes from src to dest public _bcopy _bcopy proc near push bp mov bp,sp push es push si push di push cx mov ax,ds ; set to same data segment mov es,ax mov si,[bp+4+0] ; offset of source mov di,[bp+4+2] ; offset of destination mov cx,[bp+4+4] ; count cld push di ; push dest address for return jcxz bcopy2 ; z = nothing to copy or di,di ; is destination NULL? jz bcopy2 ; z = yes, don't do a thing cmp si,di ; is source after destination? ja bcopy1 ; a = yes, no overlap problem je bcopy2 ; e = same place, do nothing add di,cx ; start at the ends dec di add si,cx dec si std ; work backward bcopy1: rep movsb bcopy2: pop ax ; recover return destination cld pop cx pop di pop si pop es mov sp,bp pop bp ret _bcopy endp ; void * bcopy(src, dest, count) ; void * FAR dest, * FAR src; ; size_t count; ; copy count bytes from src to dest public _bcopyff _bcopyff proc near push bp mov bp,sp push es push ds push si push di push cx push dx lds si,dword ptr [bp+4+0] ; source les di,dword ptr [bp+4+4] ; destination mov cx,[bp+4+8] ; count cld jcxz bcopyff2 ; z = nothing to copy mov ax,ds mov dx,es or ax,ax ; is destination NULL? jz bcopyff2 ; z = yes, don't do a thing cmp ax,dx ; is source seg after destination? ja bcopyff1 ; a = yes, no overlap problem jb bcopyff3 ; b = no, no overlap the other way cmp si,di ; is source offset after destination? ja bcopyff1 ; a = yes, no overlap problem je bcopyff2 ; e = same place, do nothing bcopyff3:add di,cx ; start at the ends dec di add si,cx dec si std ; work backward bcopyff1:rep movsb bcopyff2:xor ax,ax ; say null destination cld pop dx pop cx pop di pop si pop ds pop es mov sp,bp pop bp ret _bcopyff endp ; void * memset(dest, c, count) ; void *dest; ; char c; ; size_t count; ; Store count copies of byte c in destination area dest public _memset _memset proc near push bp mov bp,sp push es push di push cx mov ax,ds ; setup data segment mov es,ax mov di,[bp+4+0] ; offset of destination or di,di ; is it NULL? jz memset1 ; z = yes, don't do a thing push di ; save dest for return mov al,[bp+4+2] ; byte of character c mov ah,al mov cx,[bp+4+4] ; count jcxz memset1 ; z = do nothing cld shr cx,1 jnc memset2 stosb memset2:rep stosw pop ax ; return pointer to destination memset1:pop cx pop di pop es mov sp,bp pop bp ret _memset endp ; Allocate size bytes from DOS free memory. ; void FAR * malloc(size_t size) ; Returns FAR pointer in dx:ax, or 0L if failure. Size is an unsigned int. public _malloc _malloc proc near push bp mov bp,sp push bx push cx mov bx,[bp+4+0] ; bytes wanted add bx,15 ; round up mov cl,4 shr bx,cl ; convert to # of paragraphs mov cx,bx ; remember quantity wanted mov ah,allocmem ; DOS memory allocator int dos ; returns segment in ax jc malloc1 ; c = fatal error cmp cx,bx ; paragraphs wanted vs delivered je malloc2 ; e = got the block push es ; insufficient, return it mov es,ax ; identify the block mov ah,freemem ; free the unwanted block int dos pop es malloc1:xor ax,ax ; return 0L on failure malloc2:mov dx,ax ; segment xor ax,ax ; offset pop cx pop bx pop bp ret _malloc endp ; Free a block of memory allocated from the DOS memory pool. ; void free(FAR * memblock); public _free _free proc near push bp mov bp,sp push ax push es mov ax,[bp+4+2] ; get high order (segment) arg or ax,ax ; NULL? jz free1 ; z = yes, leave it alone mov es,ax ; identify the block mov ah,freemem ; free the unwanted block int dos free1: pop es pop ax pop bp ret _free endp ; int fstchr(const char FAR * p, word len, byte c) ; finds first occurence of unsigned byte in low part of c and returns ; the number of bytes preceeding it in the buffer, or len if not found. public _fstchr _fstchr proc near push bp mov bp,sp push es push bx push cx push di les di,dword ptr [bp+4+0] ; Far string address mov bx,es ; check for NULL mov ax,-1 ; error return value or bx,bx ; NULL? jz fstchr1 ; z = yes, return -1 mov bx,di ; remember starting offset mov cx,[bp+4+4] ; number of bytes to examine jcxz fstchr1 ; z = empty string, return -1 mov ax,[bp+4+6] ; pattern is in al cld repne scasb mov ax,di ; ending place dec ax ; minus auto inc of rep sub ax,bx ; minus starting offset fstchr1:pop di pop cx pop bx pop es pop bp ret _fstchr endp ; Timer routines - use set_*timeout to receive a clock value which ; can later be tested by calling chk_timeout with ; that clock value to determine if a timeout has ; occurred. chk_timeout returns 0 if NOT timed out. ; Usage: long set_timeout( int seconds ); ; long set_ttimeout( int bios_ticks ); ; int chk_timeout( long value ); ; ; (c) 1990 University of Waterloo, ; Faculty of Engineering, ; Engineering Microcomputer Network Development Office ; version ; 0.1 7-Nov -1990 E. P. Engelke public _set_ttimeout _set_ttimeout proc near push bp mov bp,sp push es xor ax,ax cwd mov es,ax mov ax,[bp+4+0] ; initial Bios clock ticks pushf ; critical section cli add ax,es:[BIOSCLK+0]; adc dx,es:[BIOSCLK+2]; popf ; end critical section pop es pop bp ret _set_ttimeout endp public _set_timeout _set_timeout proc near push bp mov bp,sp push es push cx xor ax,ax ; reference low memory mov es,ax mov ax,[bp+4+0] ; seconds xor dx,dx mov cx,1165 mul cx ; 1165/64 = 18.203... mov cx,6 tmp: shr dx,1 rcr ax,1 loop tmp pushf ; critical section cli add ax,es:[BIOSCLK+0] adc dx,es:[BIOSCLK+2] popf ; end critical section pop cx pop es pop bp ret _set_timeout endp public _chk_timeout _chk_timeout proc near push bp mov bp,sp push cx push es xor ax,ax mov es,ax pushf ; critical section cli mov cx,es:[BIOSCLK+0] mov bx,es:[BIOSCLK+2] popf ; end critical section pop es mov ax,[bp+4+0] ; timeout value mov dx,[bp+4+2] cmp dx,bx ; if timeout < clock, has expired jb ret_tru cmp ax,cx jbe ret_tru ; may have gone over by one day sub ax,LO_MAX sbb dx,HI_MAX jc ret_fal ; c = nope, timeout is today ; test timeout new values cmp dx,bx jb ret_tru cmp ax,cx ja ret_fal ret_tru:mov ax,1 ; say have timed out pop cx pop bp ret ret_fal:xor ax,ax ; say have not timed out pop cx pop bp ret _chk_timeout endp ; unsigned long realclock(void) public _realclock _realclock proc near ; get Bios time of day dword push es xor ax,ax ; reference low memory mov es,ax pushf ; critical section cli mov ax,es:[BIOSCLK+0] ; return Bios time of day tick count mov dx,es:[BIOSCLK+2] popf ; end critical section pop es ret _realclock endp ; void _chkstk() ; Stack checker ; { ; ; ; } public __chkstk, __aNchkstk __chkstk proc near ; MSC v5.1 __aNchkstk equ this byte ; MSC v6.00 pop bx ; pop return address sub sp,ax ; down adjust stack pointer jmp bx ; return the no-stack way __chkstk endp ; Microsoft C v7.0 direct support. Shift left dx:ax by cx. No C calling conv. ; Long shift left public __aNlshl __aNlshl proc near jcxz lshift2 ; z = no shift lshift1:shl ax,1 rcl dx,1 loop lshift1 lshift2:ret __aNlshl endp ; Microsoft C v7.0 direct support. Shift rgt dx:ax by cx. No C calling conv. ; Unsigned long shift right public __aNulshr __aNulshr proc near jcxz rshift2 ; z = no shift rshift1:shr dx,1 rcr ax,1 loop rshift1 rshift2:ret __aNulshr endp ; void ; outch(char ch) ; Sends character to the screen via the msgbuf buffer if operating at ; interrupt level, or via DOS if operating at task level. public _outch _outch proc near push bp mov bp,sp push ax push bx cmp _display_mode,0 ; quiet screen? je outch3 ; e = yes mov al,[bp+4] ; get the character cmp _doslevel,0 ; at DOS task level? je outch1 ; e = no mov ah,conout ; use DOS push dx mov dl,al int dos pop dx jmp short outch3 outch1: cmp _msgcnt,MSGBUFLEN ; is buffer filled? ja outch3 ; a = yes, discard this byte mov bx,_msgcnt mov _msgbuf[bx],al inc _msgcnt outch3: pop bx pop ax mov sp,bp pop bp ret _outch endp ; void ; outsn(char * string, int count) ; display counted string public _outsn _outsn proc near push bp mov bp,sp push ax push si mov si,[bp+4] ; string address mov cx,[bp+4+2] ; string length cld outsn1: lodsb or al,al jz outsn2 push ax ; push arg call _outch pop ax ; clean stack loop outsn1 outsn2: pop si pop ax mov sp,bp pop bp ret _outsn endp ; void ; outs(char * string) ; display asciiz string public _outs _outs proc near push bp mov bp,sp push ax push si mov si,[bp+4] ; asciiz string address cld outs1: lodsb or al,al ; terminator ? jz outs2 ; z = yes push ax ; push arg call _outch pop ax ; clean stack jmp short outs1 outs2: pop si pop ax mov sp,bp pop bp ret _outs endp ; void ; outhex(char c) ; display char in hex public _outhex _outhex proc near push bp mov bp,sp push ax mov ax,[bp+4] ; incoming character mov cl,4 shr al,cl call outh mov ax,[bp+4] call outh pop ax mov sp,bp pop bp ret ; worker for outhex outh proc near and al,0fh cmp al,9 jbe outh1 add al,'A' - '9' - 1 outh1: add al,'0' push ax call _outch pop ax ret outh endp _outhex endp ; output a string of hex chars ; void ; outhexes(char * string, int count ) public _outhexes _outhexes proc near push bp mov bp,sp push ax push si ; preserve such things mov si,[bp+4] ; get string pointer mov cx,[bp+4+2] ; get char count jcxz outhexs2 ; z = nothing cld outhexs1:lodsb ; read a byte push cx ; save loop counter push ax call _outhex ; display as hex pair add sp,2 ; clean stack pop cx loop outhexs1 ; do count's worth outhexs2:pop si pop ax mov sp,bp pop bp ret _outhexes endp _TEXT ends end