Closer still on asm.js

Split apart boot.fs some more.

common/extra2.fs

@@ -0,0 +1,24 @@
+\ Copyright 2022 Bradley D. Nelson
+\
+\ Licensed under the Apache License, Version 2.0 (the "License");
+\ you may not use this file except in compliance with the License.
+\ You may obtain a copy of the License at
+\
+\     http://www.apache.org/licenses/LICENSE-2.0
+\
+\ Unless required by applicable law or agreed to in writing, software
+\ distributed under the License is distributed on an "AS IS" BASIS,
+\ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+\ See the License for the specific language governing permissions and
+\ limitations under the License.
+
+( Fill, Move )
+: cmove ( a a n -- ) for aft >r dup c@ r@ c! 1+ r> 1+ then next 2drop ;
+: cmove> ( a a n -- ) for aft 2dup swap r@ + c@ swap r@ + c! then next 2drop ;
+: fill ( a n ch -- ) swap for swap aft 2dup c! 1 + then next 2drop ;
+: erase ( a n -- ) 0 fill ;   : blank ( a n -- ) bl fill ;
+
+( Compound words requiring conditionals )
+: min 2dup < if drop else nip then ;
+: max 2dup < if nip else drop then ;
+: abs ( n -- +n ) dup 0< if negate then ;