Hi, On Tue, Apr 11, 2017 at 1:26 AM, Mateusz Viste <mate...@nospam.viste.fr> wrote: > On Mon, 10 Apr 2017 23:30:35 -0500, Rugxulo wrote: >> >> Unless I'm mistaken, conditional jumps on 8086 don't go beyond -128 .. >> 127 (signed) byte range. Hence the billions of workarounds (TASM >> "jumps", MASM "option ljmp", etc). > > I won't argue about what opcode is or is not available on 8086, since I > did not bother decoding their exact meaning. I do see however that (NASM > at least) can assemble JZ and JZ SHORT in two very different forms, JZ > SHORT being significantly shorter. > > 5 00000000 B80100 mov ax, 1 > 6 00000003 48 dec ax > 7 00000004 746A jz short gameover > > 5 00000000 B80100 mov ax, 1 > 6 00000003 48 dec ax > 7 00000004 7503E9DD01 jz gameover > > Of course NASM always uses the short form whenever it's possible, but > when the jump is too far away it silently uses the longer form, hence the > need to always specify SHORT if one wants to be sure what's going on.
AFAIK, the longer one is 386+ only, hence not available with "cpu 8086". Thus, if it still quietly assembles, that is a bug (but I thought that was long-ago fixed/avoided). ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
