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MMIX Bug

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Content

MMIXware Version

mmix-20131017

Bug Reported

Initial: 27/8/2015

Author

Andreas Scherer and Martin Ruckert

Description

The bug fix for the rI and rU as described in "rI and rU are not implemented according to specification" was not implemented correctly. The parenteses around "&" in "if ((g[rU].h&0x7fff)==0) g[rU].h-=0x8000;" were omitted. As a consequence mmix-sim would behave different than mmix-pipe (see section 146 of mmix-pipe.w).

Proposed patch

Replace
        g[rU].h++;@+ if (g[rU].h&0x7fff==0) g[rU].h-=0x8000;@+
by
        g[rU].h++;@+ if ((g[rU].h&0x7fff)==0) g[rU].h-=0x8000;@+

Discussion

The patch as given above is in the source repository.

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