XPost: comp.os.msdos.programmer, alt.lang.asm   
   From: terje.mathisen@nospicedham.tmsw.no   
      
   Kerr-Mudd, John wrote:   
   > Finally, a rot13 program for DOS that's smaller than the standard version   
   > with jumps:   
   >   
   >   
   > ->u 100 l2E   
   > 1637:0100 B6 02          mov          dh,02   
   > 1637:0102 B4 3F          mov          ah,3F   
   > 1637:0104 89 C1          mov          cx,ax   
   > 1637:0106 CD 21          int          21   
   > 1637:0108 89 D6          mov          si,dx   
   > 1637:010A 91             xchg         ax,cx   
   > 1637:010B E3 20          jcxzw        012D   
   > 1637:010D 51             push         cx   
      
   The loop starts here of course!   
      
   > 1637:010E AC             lodsb   
   > ; main rot13 rtn   
   > 1637:010F 24 DF          and          al,DF   
   Folding to lowercase ascii   
   > 1637:0111 2C 41          sub          al,41   
   > 1637:0113 3C 1A          cmp          al,1A   
   Checking that it was in-range   
   > 1637:0115 18 E4          sbb          ah,ah   
   > 1637:0117 3C 0D          cmp          al,0D   
      
   Very nice, handling plus/minus for upper and lower case!   
      
   > 1637:0119 D6             salc   
   > 1637:011A 25 1A F3       and          ax,F31A   
   > 1637:011D 00 E0          add          al,ah   
   > 1637:011F 00 44 FF       add          [si-01],al   
   >   
   > 1637:0122 E2 EA          loopw        010E   
   > 1637:0124 59             pop          cx   
   > 1637:0125 43             inc          bx   
   > 1637:0126 B4 40          mov          ah,40   
   > 1637:0128 CD 21          int          21   
   > 1637:012A 4B             dec          bx   
   > 1637:012B EB D5          jmp          0102   
   > 1637:012D C3             ret   
   > ->          d 100 l2E   
   > 1637:0100 B6 02 B4 3F-89 C1 CD 21-89 D6 91 E3-20 51 AC 24  ...?...!.... Q.$   
   > 1637:0110 DF 2C 41 3C-1A 18 E4 3C-0D D6 25 1A-F3 00 E0 00  .,A<...<..%.....   
   > 1637:0120 44 FF-E2 EA 59 43-B4 40 CD 21-4B EB D5 C3        D...YC.@.!K...   
   > ->          q   
   >   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)