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Assembly Source File | 1997-02-28 | 12.4 KB | 423 lines

page 60,132 title Start_Up1 -- Intermediate Start Up Code for .COM/.EXE Programs name Start_Up1 comment ÷ Start_Up1 V1.06 -------------------------------------------------------------------------- NAME startup1 Intermediate start up code for .com and .exe programs SYNOPSIS extern Start_Up1 or extern Start_Up1S See Programming Notes below for difference. DESCRIPTION This is the startup code for all .exe and .com assembly language programs. Just use the SYNOPSIS above in the main function to include this startup code in the .exe file from a .lib. For .com assembly language programs, this source code must be the first assembled so that this code is the linked first. This procedure parses the command line into argc and *argv[] similar to C. Argv[0] is the first command line argument not the program name as in C. This procedure performs the following functions in addition to above - Initializes the following global variables: -- DGRP, segment address of DGROUP -- STACK_BOTTOM, offset to stack bottom in DGROUP -- PSP, segment address of PSP -- ENVIRON, segment address of passed copy of the ENVIRONMENT -- OSMAJOR, integer part of OS system -- OSMINOR, decimal part of OS system - If DOS version is less than 2.0, aborts with error message - Initializes DS and ES segment registers to DGROUP - Shrinks memory down to size of program by releasing all memory above program RETURNS If main returns to startup code. The program terminiates with the return code in AL. PROGRAMING NOTES Assembled with Microsoft MASM V6.11d with options: /Cp /W3 /Wx /memmod={see below}. Do not use the /NOI switch with linker. Written to link with any memory model. Use MEMMOD to specify the memory model. /dMEMMOD=TINY|SMALL|COMPACT|MEDIUM|LARGE|HUGE Written using the FORTRAN/PASCAL/BASIC calling convention so passed parameters are pushed in the order of appearance in the proc declaration. This procedure can pass argc and argv on stack two ways. The proc declaration in the MAIN procedure will differ depending upon the choice. The default requires the following proc declaration: MAIN proc ARGC:word, ARGV:ptr If SIMPLE is defined, an alternate proc declaration is required: MAIN proc ARGV:ptr, ARGC:word Here, ARGV is not a pointer to an array of pointers but the location of the 1st pointer. In Huge memory model, the pointers passed in ARGV are long pointer vice huge pointers. MEMORY REQUIREMENTS (in bytes) Tiny Small Medium Compact Large Huge Code: 165 190 192 193 195 195 Code (SIMPLE): 162 187 189 189 191 191 _Data: 0 0 0 0 0 0 Const: 0 0 0 0 0 0 _BBS: 12 12 12 12 12 12 Stack: ? ? ? ? ? ? The first code size is for SIMPLE not defined. The Code (SIMPLE) is for when SIMPLE is defined. Stack usage is determined by the size of and the number of arguments in the command line. Note: The 12 bytes in _BSS are from sudata.asm which is used so that all startup code can reside in the same .lib file. CAUTION Startup1 defines a 512 byte stack. This should be enough for programs who make moderate use of the stack. If automatic variables are used extensively, more stack space should be defined in the main module unless using the tiny memory model. In this case, the startup code must be the first souce file in the build, change the size of the STACK_SIZE define. Linker option, NO IGNORE CASE, is not used so that the linker will handle __end properly. EXTERNAL LIBRARIES sudata alib? EXTERNAL PROCEDURES main user defined INTERUPTS CALLED Int 21h 30h - Get Version Number Int 21h 4ah - Set Memory Block Size Int 21h 4ch - Terminate program with return code GLOBAL NAMES Startup_1 or Startup_1S AUTHOR Raymond Moon - 7 Sep 87 Copyright (c) 1987, 1988, 1994, 1995, 1996 - MoonWare ALL RIGHTS RESERVED VERSION Version - Date - Remarks 1.00 - 7 Sep 87 - Original 1.01 - 13 Feb 88 - Updated program to parse command line - This created Startup1 from Startup0 1.02 - 4 Jul 88 - Converted to MASM V5.1 1.03 - 9 Oct 88 - Added Stack_Bottom & ZZ_PRGM_TOP segment to determine end of data. 1.04 - 30 Oct 94 - Moved ZZ_PRGM_TOP segment position in file. - Removed increment in program size in paras as ZZ_PRGM_TOP is aligned on a para. 1.05 - 5 Mar 95 - Added TINY Model capability - Converted to .dosseg using __end vice ZZ_PRGM_TOP for end of data - Removed checking for DOS Ver 1.0 and terminating with error message. 1.06 - 29 Dec 96 - Optimized the .com coding ========================================================================== ÷ Commend End ;----------------------------- ; A Make the small memory model the default ifndef memmod memmod equ <small> endif ;----------------------------- ; B Include the processor, memory model, associate ES register with ; DGROUP, and specify DOS segment order. include procesor.inc % .MODEL memmod,FORTRAN assume es:DGROUP .dosseg ;---------------------------- ; C Required includes include startup.inc ;---------------------------- ; D Define any required equates STACK_SIZE equ 512 ;========================================================================= ; DATA ;========================================================================= ; E Define storage for the various global and system variables. if @Model NE 1 .STACK STACK_SIZE ; Define a nominal stack endif ;---------------------------- ; F Define __end which is defined when using .dosseg externdef __end:byte ;---------------------------- ; G Define segment for addressing information in the PSP PSP_SEG segment at 00h org 2h NEXTPARA_PTR dw ? ; Segment address of next memory para org 2ch ENVIRON_PTR dw ? ; Segment address of Environment org 80h PARM_LEN db ? ; Number of bytes in Command Line tail PARMS db 127 dup(?) ; Start of Command Line tail PSP_SEG ends ;========================================================================= ; CODE ;========================================================================= ; H Put the called main procedure in the proper relationship to the ; startup code. if @CodeSize extrn Main:far .CODE else .CODE extrn Main:near endif ;----------------------------- ; I Include org statement if tiny model if @Model EQ 1 org 100h endif ;----------------------------- ; J Start the Start_Up1 code. Make it a far procedure so error return ; will work. If SIMPLE is defined, redefined Start_Up1 as Start_Up1S. ifdef SIMPLE Start_Up1 equ <Start_Up1S> endif % Start_Up1 proc far ;----------------------------- ; K First, initialize global variables. Set DS to DGROUP. ; Skip DGROUP code for .com(Tiny) memory models if @Model NE 1 mov ax, DGROUP ; Get seg address of DGROUP mov ds, ax ; Initialize DS segment register mov DGRP, ax ; Initialize DGRP assume es:PSP_SEG else mov DGRP, ds ; Initialize DGRP endif mov PSP, es ; Initialize PSP if @Model eq 1 assume ds:PSP_SEG endif mov bx, ENVIRON_PTR ; Get segment address of environment mov cx, NEXTPARA_PTR ; Get segment address of next memory if @Model eq 1 assume ds:DGROUP endif mov ENVIRON, bx ; Initialize ENVIRON mov NEXTPARA, cx ; Initialize NEXTPARA mov ah, 30h ; Get DOS version number int 21h ; Call DOS mov OSMAJOR, al ; Save major version number mov OSMINOR, ah ; Save minor version number ;---------------------------- ; L Combine the stack into DGROUP so that it is addressable from DGROUP. ; Initialize STACK_BOTTOM. lea bx, __end ; Get pointer to end of data if @Model eq 1 ; Ensure that Stack bottom at paragraph add bx, 15 ; Add to ensure next para if necessary and bx, 0fff0h ; Truncate to a paragraph boundary endif mov STACK_BOTTOM, bx ; Save it if @Model eq 1 ; Get stack size add bx, STACK_SIZE ; DI = stack size else add bx, sp ; DI = stack size endif mov dx, ds ; Get DGROUP segment address mov ss, dx ; Reset SS mov sp, bx ; Reset SP ;---------------------------- ; M Release all memory above program. Calculate the size of the program ; in paragraphs (16 bits). BX starts with Stack Top mov cl, 4 ; Convert to #para by dividing by 16 shr bx, cl ; Do division by bit shifting if @Model ne 1 ; Needed in non-Tiny memory models mov ax, ds ; AX => DGROUP sub ax, PSP ; AX = # para for code add bx, ax ; BX = # para in program endif mov ah, 4ah ; Request DOS set block int 21h ; Call DOS ;---------------------------- ; N See if there are any command line arguments. If not, all command ; line processing is skipped. The pushed null on the stack will be ; argc, and a null pointer is also pushed onto the stack so argv[0] ; is a null pointer. xor dx, dx ; Ensure DX is null push dx ; Ensure null on top of stack mov bp, sp ; BP = top of stack if @Model NE 1 cmp es:PARM_LEN, 0 ; Are there any Command Line arguments else assume ds:PSP_SEG cmp PARM_LEN, 0 ; Are there any Command Line arguments assume ds:DGROUP endif jne SU1 ; No, go process what is on the stack push dx ; Push null pointer if @DataSize push dx ; Make a doubleword null pointer endif if @Model NE 1 mov es, DGRP ; Initialize ES for all except tiny endif jmp short SU7 ; Go call MAIN ;---------------------------- ; O There are command line arguments. Parse them onto the stack and ; build ARGC and ARGV. Start this by transferring the entire command ; line tail onto the stack. Make room for them by moving SP. SU1: if @Model NE 1 mov ds, PSP ; DS => PSP endif assume ds:PSP_SEG mov cl, PARM_LEN ; Get # of bytes in Command Line inc cx ; increase by one and cx, 0feh ; Force an even count mov ax, sp ; Get SP sub ax, cx ; Subtract PARM_LEN mov sp, ax ; Reset SP, room on Stack lea si, PARMS ; Load source addr in SI mov di, sp ; Load destin addr in DI if @Model NE 1 mov es, DGRP ; ES => DGROUP endif assume es:DGROUP rep movsb ; Move Command Line onto the Stack if @Model NE 1 mov ds, es:DGRP ; Restore DS endif assume ds:DGROUP ;----------------------------- ; P Convert all blanks, not within double quotes, in the Command Line ; to Nul. CX is IN_LITERAL_FLAG. Build argv[] at the same time. xor di, di ; DI set to zero, DI = arg count mov bx, bp ; BX points to last byte in stack mov bp, sp ; BP is the stop point xor cx, cx ; Clear IN_LITERAL_FLAG SU2: mov al, [bx] ; Get byte cmp al, '"' ; Is it a literal? jne SU3 ; No, go to next test inc cx ; Set IN_LITERAL_FLAG and cx, 1 ; Ensure only 0, & 1 valid jmp short SU4 ; Continue, and blank '"' SU3: cmp al, ' ' ; Is it a blank? ja SU6 ; No, go set up to get another or cx, cx ; Is IN_LITERAL_FLAG clear? jne SU6 ; No, do not null blank SU4: mov byte ptr [bx], 0 ; Store Nul in [BX] SU5: or byte ptr [bx + 1], 0 ; Was the previous char null? jz SU6 ; Yes, do not push pointer if @datasize push ss ; Push segment address endif mov ax, bx ; AX => Null inc ax ; AX => 1st char push ax ; Push the offset xor cx, cx ; Clear in literal flag inc di ; Account for another arg SU6: dec bx ; BX point to next byte cmp bx, bp ; Are we through yet? jnb SU2 ; No, go one mo' 'gin ;----------------------------- ; Q Have finished building *argv[]. SP => argv[], and DI = argc. ; Create argc and argv on the stack using the FORTRAN calling ; convention. If SIMPLE is defined, push only argc. See documentation ; above for structure of proc declaration in MAIN procedure ifndef SIMPLE mov bx, sp ; BX = **argv[] push di ; Push argc if @DataSize push ss ; Long pointer endif push bx ; Push **argv[] else push di ; Push argc endif ;----------------------------- ; R call MAIN SU7: call Main ; Call MAIN procedure ;---------------------------- ; S If main returns, the program is to terminate with the return code ; returned in AL mov ah, 4ch ; End process int 21h ; Call DOS % Start_Up1 endp % end Start_Up1 ; Indicate that Start_Up1 is the start ; of the program