sub128
sub128( a0, a1, term0, term1, &rem0, &rem1 );
sub128( aSig, 0, term0, term1, &rem0, &rem1 );
sub128( aSig, 0, term0, term1, &rem0, &rem1 );
sub128( bSig, 0, aSig, zSig1, &zSig0, &zSig1 );
sub128( aSig, 0, bSig, zSig1, &zSig0, &zSig1 );
sub128( aSig, rem1, term0, term1, &rem0, &rem1 );
sub128( rem1, 0, term1, term2, &rem1, &rem2 );
sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
sub128( term0, term1, aSig0, aSig1, &alternateASig0, &alternateASig1 );
sub128( aSig0, aSig1, term0, term1, &rem0, &rem1 );
sub128( rem1, 0, term1, term2, &rem1, &rem2 );
sub128( bSig0, bSig1, aSig0, aSig1, &zSig0, &zSig1 );
sub128( aSig0, aSig1, bSig0, bSig1, &zSig0, &zSig1 );
if ( q ) sub128( aSig0, aSig1, bSig0, bSig1, &aSig0, &aSig1 );
sub128( aSig0, 0, term1, term2, &aSig0, &aSig1 );
sub128( aSig0, aSig1, term1, term2, &aSig0, &aSig1 );
sub128( aSig0, aSig1, bSig0, bSig1, &aSig0, &aSig1 );
if ( zSign ) sub128( 0, 0, aSig0, aSig1, &aSig0, &aSig1 );
sub128( aSig0, aSig1, term0, term1, &rem0, &rem1 );
sub128( rem1, 0, term1, term2, &rem1, &rem2 );