snapshot of carry flag implementation

Tests failing.

This approach seems wrong. I'm not sure even the tests are correct. Also,
some open questions:

1. Should setting the overflow flag always set the carry flag?
2. Should the carry flag only be set on add/subtract/compare, or by all
arithmetic ops?
3. Had to turn off the -ftrapv flag in `build`. Is there a way to detect
overflow without actually causing overflow?

Once we start setting CF correctly we have to implement jump above/below
instructions (8- and 32-bit displacement variants).

https://github.com/akkartik/mu/issues/30

1 files changed, 1 insertions, 1 deletions

diff --git a/subx/build b/subx/build
index 614b07d8..f29518ac 100755
--- a/subx/build
+++ b/subx/build
@@ -22,7 +22,7 @@ UNTIL_LAYER=${2:-zzz}
 test "$CXX" || export CXX=c++
 test "$CC" || export CC=cc
 test "$CFLAGS" || export CFLAGS="-g -O3"
-export CFLAGS="$CFLAGS -Wall -Wextra -ftrapv -fno-strict-aliasing"
+export CFLAGS="$CFLAGS -Wall -Wextra -fno-strict-aliasing"
 
 # return 1 if $1 is older than _any_ of the remaining args
 older_than() {