to-upper and to-lower move to strings.mk
So that config.mk can use these functions.
Test: builds
Change-Id: I6634226cbed56c34977803ff9c75b8d481c21c34
diff --git a/core/strings.mk b/core/strings.mk
new file mode 100644
index 0000000..98dbb0f
--- /dev/null
+++ b/core/strings.mk
@@ -0,0 +1,44 @@
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# 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.
+#
+
+###########################################################
+## Convert to lower case without requiring a shell, which isn't cacheable.
+##
+## $(1): string
+###########################################################
+to-lower=$(subst A,a,$(subst B,b,$(subst C,c,$(subst D,d,$(subst E,e,$(subst F,f,$(subst G,g,$(subst H,h,$(subst I,i,$(subst J,j,$(subst K,k,$(subst L,l,$(subst M,m,$(subst N,n,$(subst O,o,$(subst P,p,$(subst Q,q,$(subst R,r,$(subst S,s,$(subst T,t,$(subst U,u,$(subst V,v,$(subst W,w,$(subst X,x,$(subst Y,y,$(subst Z,z,$1))))))))))))))))))))))))))
+
+###########################################################
+## Convert to upper case without requiring a shell, which isn't cacheable.
+##
+## $(1): string
+###########################################################
+to-upper=$(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst x,X,$(subst y,Y,$(subst z,Z,$1))))))))))))))))))))))))))
+
+# Sanity-check to-lower and to-upper
+lower := abcdefghijklmnopqrstuvwxyz-_
+upper := ABCDEFGHIJKLMNOPQRSTUVWXYZ-_
+
+ifneq ($(lower),$(call to-lower,$(upper)))
+ $(error to-lower sanity check failure)
+endif
+
+ifneq ($(upper),$(call to-upper,$(lower)))
+ $(error to-upper sanity check failure)
+endif
+
+lower :=
+upper :=