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MSDOS/Virus.MSDOS.Unknown.free.asm

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+          title  FREE.ASM
+          page,132
+
+cseg      segment para 'code'
+          assume cs:cseg
+main      proc   far
+          org    100h
+start:
+          jmp    begin
+
+banner    db     0ah,'FREE Vers 1.0 - Sept. 1985 - by Art Merrill',0dh,0ah,'$'
+          db     'Copyright (C) 1985',0dh,0ah,'$'
+          db     'Ziff-Davis Publishing Company',0dh,0ah,'$'
+total:    db     0ah,8 dup(0),' bytes total disk space',0dh,0ah
+diff:     db     8 dup(0),' bytes allocated',0dh,0ah
+bytes:    db     8 dup(0),' bytes available on disk',0dh,0ah,0ah,'$'
+hltotal:  dw     0,0
+hlbytes:  dw     0,0
+
+begin:
+          mov    dx,offset banner
+          mov    ah,9
+          int    21h
+
+          mov    si,5ch                ;address of selected drive
+          mov    dl,[si]
+          mov    ah,36h                ;get disk free space
+          int    21h
+
+          push   ax                    ;save for total bytes
+          push   cx                    ;save for total bytes
+          push   dx                    ;save for total bytes
+
+          mul    bx                    ;get total clusters
+          mul    cx                    ;get total bytes
+
+          std
+          mov    di,offset hlbytes+2
+          xchg   ax,dx
+          stosw
+          xchg   ax,dx
+          stosw
+
+          mov    di,offset bytes+7     ;storage for ascii printout
+          call   ascii
+
+          pop    dx                    ;get back total clusters
+          pop    cx                    ;get back bytes per sector
+          pop    ax                    ;get back sectors per cluster
+
+          mul    dx                    ;total clusters
+          mul    cx                    ;bytes per sector
+
+          mov    di,offset hltotal+2   ;same routine as above to get
+          xchg   ax,dx                 ;  total bytes
+          stosw
+          xchg   ax,dx
+          stosw
+
+          mov    di,offset total+8     ;storage for ascii printout
+          call   ascii
+
+          mov    ax,word ptr hltotal+2 ;calculate difference between
+          sub    ax,word ptr hlbytes+2 ;  total bytes and bytes allocated
+          xchg   ax,dx                 ;  to get total bytes remaining
+          mov    ax,word ptr hltotal
+          sub    ax,word ptr hlbytes
+          jnc    skip
+          dec    dx                    ;adjust total for carry
+skip:
+          mov    di,offset diff+7      ;storage for ascii printout
+          call   ascii
+
+          mov    dx,offset total       ;print results
+          mov    ah,9
+          int    21h
+
+          int    20h                   ;exit
+
+main      endp
+
+ascii     proc   near
+          xchg   bp,dx                 ;save high word
+          mov    bx,0ah                ;divisor
+          mov    cl,30h                ;conversion for ascii
+rpt1:
+          cmp    bp,0                  ;are we done with high words
+          jz     rpt2                  ;yes
+          xchg   ax,bp                 ;no-get high word
+          xor    dx,dx                 ;clear dx
+          div    bx
+          xchg   bp,ax                 ;this will be the new high word
+          div    bx                    ;divide low word + remainder
+          or     dl,cl                 ;convert hex value to ascii
+          mov    [di],dl               ;quotient into storage
+          dec    di                    ;step back one byte
+          jmp    rpt1                  ;go again
+rpt2:
+          xor    dx,dx                 ;clear dx
+          div    bx
+          or     dl,cl                 ;convert hex value to ascii
+          mov    [di],dl               ;quotient into storage
+          dec    di                    ;step back one byte
+          cmp    ax,0                  ;are we done?
+          jnz    rpt2                  ;no
+
+          ret                          ;yes
+ascii     endp
+
+cseg      ends
+          end    start
+