io Programmo 23

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Assembly Source File | 1994-11-15 | 6.4 KB | 274 lines

page 59,132 comment COMPRES & RESTOR ---------------- Purpose: -------- COMPRES and RESTOR are sample program to show how huffman compression works. Single files can be compressed by the COMPRES program, then decompressed by the RESTOR program. Using COMPRES & RESTOR ---------------------- To compress a file type "COMPRES file1 file2". The first file (file1) is the file to be compressed and the second file is what to call the result. RESTOR works in the reverse. "RESTOR file1 file2" will decompress file1 and put at file2. Compression Overview -------------------- The compression/decompression engines are initiated with a pointer to two routines. One routine will feed data to the engine and the other will store the output. Next, one call to the compression entry point will continue compressing until the input (feed) routine runs out of data. Performance ----------- Compression speed and size is respectable, but not competative with programs such as PKZIP and ARJ. For most compression jobs of less than a megabyte the speed will be acceptable. extrn shrink:far extrn expand:far extrn DWORD_TO_HEX_CRT:far extrn library_setup:far extrn library_terminate:far ;; extrn lib_error_handler:far extrn parse_first:far extrn parse_next:far extrn file_size1:far extrn SHOW_CURSOR:far extrn key_read:far extrn lib_info:byte .xlist include mac.inc include common.inc .list code segment assume cs:code,ds:nothing ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ; FEED - fill buffer for shrink/expand ; inputs: ds:dx = buffer ptr of size (disk_buf_size) ; ax = requested amount ; output: ax = number of bytes placed in buffer, 0=end of input ;------------------- feed_handle dw 0 feed_count dd 0 ;------------------- feed proc far apush cx,bx mov cx,ax ;amount of data to read mov bx,cs:feed_handle ;file handle mov ah,3fh ;read code int 21h add word ptr cs:feed_count,ax adc word ptr cs:feed_count+2,0 apush ax,dx mov ah,3 mov bh,0 int 10h ;read cursor posn -> dx mov dl,8 mov ah,2 int 10h ;set cursor posn mov ax,word ptr cs:feed_count mov dx,word ptr cs:feed_count+2 call DWORD_TO_HEX_CRT apop dx,ax apop bx,cx retf feed endp ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ ; STORE - save buffer data somewhere ; inputs: ds:dx = buffer ptr ; ax = amount of data present in buffer ; output: none ;------------------- store_handle dw 0 store_count dd 0 ;------------------- store proc far apush ax,bx,cx add word ptr cs:store_count,ax adc word ptr cs:store_count+2,0 mov cx,ax ;set write length mov bx,cs:store_handle mov ah,40h int 21h push dx mov ah,3 mov bh,0 int 10h ;read cursor posn -> dx mov dl,27 mov ah,2 int 10h ;set cursor posn mov ax,word ptr cs:store_count mov dx,word ptr cs:store_count+2 call DWORD_TO_HEX_CRT pop dx apop cx,bx,ax retf store endp ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ assume cs:code,ds:code ;██████████████████████████████████████████████████████████████████████████ infile_asciiz db 40 dup (0) outfile_asciiz db 40 dup (0) help_msg db 0dh,0ah db 'COMPRESS compresses a file to smaller size.',0dh,0Ah db 'usage: ',0dh,0Ah db ' COMPRESS <file1> <file2> ',0dh,0ah db 0dh,0ah db ' <file1> is compressed and stored at <file2>',0dh,0ah db 'Press any key to continue.$' info_msg db 'Reading Writing$' ;-------------------------- start proc far cld mov bp,ds ;save PSP seg mov bx,cs mov ds,bx mov es,bx ; next, release memory beyond the end of the program ; The definition for ZSEG marks the ; end of the program's code, data and stack area. mov ax,zseg mov bx,bp mov es,bp sub bx,ax neg bx ; size of program in paragraphs mov ah,4Ah ; resize memory block int 21h push ds pop es ; ; check if enough memory free to run program ; mov ax,bp ;pass psp segment to setup mov bx,0 ;number of floating point variables call library_setup cmp ax,128 jae got_enough_mem ;jmp if 128k of memory avail ;; mov al,7 ;; mov ah,fatal_return ;; call lib_error_handler jmp exitx got_enough_mem: push ds pop es mov di,offset infile_asciiz call parse_first cmp bh,7 jne parse_err mov di,offset outfile_asciiz call parse_next cmp bh,7 jne parse_err ; ; open the input file ; mov ax,3d00h mov dx,offset infile_asciiz int 21h jc parse_err mov feed_handle,ax mov ax,3c00h mov cx,0 ;file attributes mov dx,offset outfile_asciiz int 21h mov store_handle,ax ; ; setup to display ; mov dx,1800h call SHOW_CURSOR mov ah,9 mov dx,offset info_msg int 21h ; ; setup for shrink/expand call ; mov si,offset feed mov di,offset store push cs pop es ; ; decode operation type ; mov bx,feed_handle call file_size1 call shrink jmp exitx parse_err: mov dx,offset help_msg mov ah,9 int 21h call key_read ; normal program exit exitx: mov bx,feed_handle cmp bx,0 je exitx1 mov ah,3eh int 21h ;close infile exitx1: mov bx,store_handle cmp bx,0 je exitx2 mov ah,3eh int 21h exitx2: mov ax,1 ;do not clear screen call library_terminate mov ax,4C00h int 21h start endp ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ code ENDS ;--------------------------------------------------------- stack_seg_e --- stack segment para stack db 2048 dup (0) stack ends ; ;------------------------------------------------------------------------- ; ; This segment definition is needed so linker will put the LIBSEG here ; before the ZSEG. We want ZSEG to be last so memory allocation will ; work correctly. ; LIBSEG segment byte public 'LIB' LIBSEG ENDS ;------------------------------------------------------------------------- ; zseg must be at the end of the program for memory allocation from ; DOS. ; zseg segment para public 'ZZ' zseg ends end start