diff --git a/core/java.mk b/core/java.mk
index ad9c71f..297f0b7 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -556,7 +556,7 @@
 $(built_dex_intermediate): PRIVATE_PROGUARD_INJAR_FILTERS := $(proguard_injar_filters)
 $(built_dex_intermediate): PRIVATE_EXTRA_INPUT_JAR := $(extra_input_jar)
 $(built_dex_intermediate): PRIVATE_PROGUARD_FLAGS := $(legacy_proguard_flags) $(common_proguard_flags) $(LOCAL_PROGUARD_FLAGS)
-$(built_dex_intermediate) : $(full_classes_proguard_jar) $(extra_input_jar) $(my_support_library_sdk_raise) $(common_proguard_flag_files) $(proguard_flag_files) $(legacy_proguard_lib_deps) $(R8_COMPAT_PROGUARD)
+$(built_dex_intermediate) : $(full_classes_proguard_jar) $(extra_input_jar) $(my_proguard_sdk_raise) $(common_proguard_flag_files) $(proguard_flag_files) $(legacy_proguard_lib_deps) $(R8_COMPAT_PROGUARD)
 	$(transform-jar-to-dex-r8)
 endif # LOCAL_USE_R8
 endif # LOCAL_PROGUARD_ENABLED
diff --git a/core/math.mk b/core/math.mk
index 44e03ce..ac3151e 100644
--- a/core/math.mk
+++ b/core/math.mk
@@ -15,44 +15,104 @@
 #
 
 ###########################################################
-# Basic math functions for positive integers <= 100
+# Basic math functions for non-negative integers <= 100
 #
 # (SDK versions for example)
 ###########################################################
-__MATH_NUMBERS :=  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 \
-                  21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \
-                  41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 \
-                  61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 \
-                  81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
+__MATH_POS_NUMBERS :=  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 \
+                      21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \
+                      41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 \
+                      61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 \
+                      81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
+__MATH_NUMBERS := 0 $(__MATH_POS_NUMBERS)
 
-# Returns true if $(1) is a positive integer <= 100, otherwise returns nothing.
+math-error = $(call pretty-error,$(1))
+math-expect :=
+math-expect-true :=
+math-expect :=
+math-expect-error :=
+
+# Run the math tests with:
+#  make -f ${ANDROID_BUILD_TOP}/build/make/core/math.mk RUN_MATH_TESTS=true
+#  $(get_build_var CKATI) -f ${ANDROID_BUILD_TOP}//build/make/core/math.mk RUN_MATH_TESTS=true
+ifdef RUN_MATH_TESTS
+  MATH_TEST_FAILURE :=
+  MATH_TEST_ERROR :=
+  math-error = $(if $(MATH_TEST_ERROR),,$(eval MATH_TEST_ERROR:=$(1)))
+  define math-expect
+    $(eval got:=$$$1) \
+    $(if $(subst $(got),,$(2))$(subst $(2),,$(got))$(MATH_TEST_ERROR), \
+      $(if $(MATH_TEST_ERROR),$(warning $(MATH_TEST_ERROR)),$(warning $$$1 '$(got)' != '$(2)')) \
+      $(eval MATH_TEST_FAILURE := true)) \
+    $(eval MATH_TEST_ERROR :=) \
+    $(eval got:=)
+  endef
+  math-expect-true = $(call math-expect,$(1),true)
+  math-expect-false = $(call math-expect,$(1),)
+
+  define math-expect-error
+    $(eval got:=$$$1) \
+    $(if $(subst $(MATH_TEST_ERROR),,$(2))$(subst $(2),,$(MATH_TEST_ERROR)), \
+      $(warning '$(MATH_TEST_ERROR)' != '$(2)') \
+      $(eval MATH_TEST_FAILURE := true)) \
+    $(eval MATH_TEST_ERROR :=) \
+    $(eval got:=)
+  endef
+endif
+
+# Returns true if $(1) is a non-negative integer <= 100, otherwise returns nothing.
 define math_is_number
 $(strip \
-  $(if $(1),,$(error Argument missing)) \
-  $(if $(word 2,$(1)),$(error Multiple words in a single argument: $(1))) \
+  $(if $(1),,$(call math-error,Argument missing)) \
+  $(if $(word 2,$(1)),$(call math-error,Multiple words in a single argument: $(1))) \
   $(if $(filter $(1),$(__MATH_NUMBERS)),true))
 endef
 
-#$(warning true == $(call math_is_number,2))
-#$(warning == $(call math_is_number,foo))
-#$(call math_is_number,1 2)
-#$(call math_is_number,no 2)
+define math_is_zero
+$(strip \
+  $(if $(word 2,$(1)),$(call math-error,Multiple words in a single argument: $(1))) \
+  $(if $(filter 0,$(1)),true))
+endef
+
+$(call math-expect-true,(call math_is_number,0))
+$(call math-expect-true,(call math_is_number,2))
+$(call math-expect-false,(call math_is_number,foo))
+$(call math-expect-false,(call math_is_number,-1))
+$(call math-expect-error,(call math_is_number,1 2),Multiple words in a single argument: 1 2)
+$(call math-expect-error,(call math_is_number,no 2),Multiple words in a single argument: no 2)
+
+$(call math-expect-true,(call math_is_zero,0))
+$(call math-expect-false,(call math_is_zero,1))
+$(call math-expect-false,(call math_is_zero,foo))
+$(call math-expect-error,(call math_is_zero,1 2),Multiple words in a single argument: 1 2)
+$(call math-expect-error,(call math_is_zero,no 2),Multiple words in a single argument: no 2)
 
 define _math_check_valid
-$(if $(call math_is_number,$(1)),,$(error Only positive integers <= 100 are supported (not $(1))))
+$(if $(call math_is_number,$(1)),,$(call math-error,Only non-negative integers <= 100 are supported (not $(1))))
 endef
 
+$(call math-expect,(call _math_check_valid,0))
+$(call math-expect,(call _math_check_valid,1))
+$(call math-expect,(call _math_check_valid,100))
+$(call math-expect-error,(call _math_check_valid,-1),Only non-negative integers <= 100 are supported (not -1))
+$(call math-expect-error,(call _math_check_valid,101),Only non-negative integers <= 100 are supported (not 101))
+$(call math-expect-error,(call _math_check_valid,),Argument missing)
+$(call math-expect-error,(call _math_check_valid,1 2),Multiple words in a single argument: 1 2)
+
 # return a list containing integers ranging from [$(1),$(2)]
 define int_range_list
-$(call _math_check_valid,$(1))$(call _math_check_valid,$(2))$(wordlist $(1),$(2),$(__MATH_NUMBERS))
+$(strip \
+  $(call _math_check_valid,$(1))$(call _math_check_valid,$(2)) \
+  $(if $(call math_is_zero,$(1)),0)\
+  $(wordlist $(if $(call math_is_zero,$(1)),1,$(1)),$(2),$(__MATH_POS_NUMBERS)))
 endef
 
-#$(call _math_check_valid,0)
-#$(call _math_check_valid,1)
-#$(call _math_check_valid,100)
-#$(call _math_check_valid,101)
-#$(call _math_check_valid,)
-#$(call _math_check_valid,1 2)
+$(call math-expect,(call int_range_list,0,1),0 1)
+$(call math-expect,(call int_range_list,1,1),1)
+$(call math-expect,(call int_range_list,1,2),1 2)
+$(call math-expect,(call int_range_list,2,1),)
+$(call math-expect-error,(call int_range_list,1,101),Only non-negative integers <= 100 are supported (not 101))
+
 
 # Returns the greater of $1 or $2.
 # If $1 or $2 is not a positive integer <= 100, then an error is generated.
@@ -61,12 +121,14 @@
   $(lastword $(filter $(1) $(2),$(__MATH_NUMBERS))))
 endef
 
-#$(call math_max)
-#$(call math_max,1)
-#$(call math_max,1 2,3)
-#$(warning 1 == $(call math_max,1,1))
-#$(warning 42 == $(call math_max,5,42))
-#$(warning 42 == $(call math_max,42,5))
+$(call math-expect-error,(call math_max),Argument missing)
+$(call math-expect-error,(call math_max,1),Argument missing)
+$(call math-expect-error,(call math_max,1 2,3),Multiple words in a single argument: 1 2)
+$(call math-expect,(call math_max,0,1),1)
+$(call math-expect,(call math_max,1,0),1)
+$(call math-expect,(call math_max,1,1),1)
+$(call math-expect,(call math_max,5,42),42)
+$(call math-expect,(call math_max,42,5),42)
 
 define math_gt_or_eq
 $(if $(filter $(1),$(call math_max,$(1),$(2))),true)
@@ -76,15 +138,23 @@
 $(if $(call math_gt_or_eq,$(1),$(2)),,true)
 endef
 
-#$(warning $(call math_gt_or_eq, 2, 1))
-#$(warning $(call math_gt_or_eq, 1, 1))
-#$(warning $(if $(call math_gt_or_eq, 1, 2),false,true))
+$(call math-expect-true,(call math_gt_or_eq, 2, 1))
+$(call math-expect-true,(call math_gt_or_eq, 1, 1))
+$(call math-expect-false,(call math_gt_or_eq, 1, 2))
 
 # $1 is the variable name to increment
 define inc_and_print
 $(strip $(eval $(1) := $($(1)) .)$(words $($(1))))
 endef
 
+ifdef RUN_MATH_TESTS
+a :=
+$(call math-expect,(call inc_and_print,a),1)
+$(call math-expect,(call inc_and_print,a),2)
+$(call math-expect,(call inc_and_print,a),3)
+$(call math-expect,(call inc_and_print,a),4)
+endif
+
 # Returns the words in $2 that are numbers and are less than $1
 define numbers_less_than
 $(strip \
@@ -94,12 +164,19 @@
         $(n)))))
 endef
 
+$(call math-expect,(call numbers_less_than,0,0 1 2 3),)
+$(call math-expect,(call numbers_less_than,1,0 2 1 3),0)
+$(call math-expect,(call numbers_less_than,2,0 2 1 3),0 1)
+$(call math-expect,(call numbers_less_than,3,0 2 1 3),0 2 1)
+$(call math-expect,(call numbers_less_than,4,0 2 1 3),0 2 1 3)
+$(call math-expect,(call numbers_less_than,3,0 2 1 3 2),0 2 1 2)
+
 _INT_LIMIT_WORDS := $(foreach a,x x,$(foreach b,x x x x x x x x x x x x x x x x,\
   $(foreach c,x x x x x x x x x x x x x x x x,x x x x x x x x x x x x x x x x)))
 
 define _int_encode
 $(if $(filter $(words x $(_INT_LIMIT_WORDS)),$(words $(wordlist 1,$(1),x $(_INT_LIMIT_WORDS)))),\
-  $(call pretty-error,integer greater than $(words $(_INT_LIMIT_WORDS)) is not supported!),\
+  $(call math-error,integer greater than $(words $(_INT_LIMIT_WORDS)) is not supported!),\
     $(wordlist 1,$(1),$(_INT_LIMIT_WORDS)))
 endef
 
@@ -135,18 +212,59 @@
 $(words $(call _int_encode,$(1)) $(call _int_encode,$(2)))
 endef
 
+$(call math-expect,(call int_plus,0,0),0)
+$(call math-expect,(call int_plus,0,1),1)
+$(call math-expect,(call int_plus,1,0),1)
+$(call math-expect,(call int_plus,1,100),101)
+$(call math-expect,(call int_plus,100,100),200)
+
 define int_subtract
-$(if $(call _int_greater-or-equal,$(call _int_encode,$(1)),$(call _int_encode,$(2))),\
+$(strip \
+  $(if $(call _int_greater-or-equal,$(call _int_encode,$(1)),$(call _int_encode,$(2))),\
   $(words $(filter-out xx,$(join $(call _int_encode,$(1)),$(call _int_encode,$(2))))),\
-    $(call pretty-error,$(1) subtract underflow $(2)))
+    $(call math-error,subtract underflow $(1) - $(2))))
 endef
 
+$(call math-expect,(call int_subtract,0,0),0)
+$(call math-expect,(call int_subtract,1,0),1)
+$(call math-expect,(call int_subtract,1,1),0)
+$(call math-expect,(call int_subtract,100,1),99)
+$(call math-expect,(call int_subtract,200,100),100)
+$(call math-expect-error,(call int_subtract,0,1),subtract underflow 0 - 1)
+
 define int_multiply
 $(words $(foreach a,$(call _int_encode,$(1)),$(call _int_encode,$(2))))
 endef
 
+$(call math-expect,(call int_multiply,0,0),0)
+$(call math-expect,(call int_multiply,1,0),0)
+$(call math-expect,(call int_multiply,1,1),1)
+$(call math-expect,(call int_multiply,100,1),100)
+$(call math-expect,(call int_multiply,1,100),100)
+$(call math-expect,(call int_multiply,4,100),400)
+$(call math-expect,(call int_multiply,100,4),400)
+
 define int_divide
-$(if $(filter 0,$(2)),$(call pretty-error,division by zero is not allowed!),$(strip \
+$(if $(filter 0,$(2)),$(call math-error,division by zero is not allowed!),$(strip \
   $(if $(call _int_greater-or-equal,$(call _int_encode,$(1)),$(call _int_encode,$(2))), \
     $(call int_plus,$(call int_divide,$(call int_subtract,$(1),$(2)),$(2)),1),0)))
 endef
+
+$(call math-expect,(call int_divide,1,1),1)
+$(call math-expect,(call int_divide,200,1),200)
+$(call math-expect,(call int_divide,200,3),66)
+$(call math-expect,(call int_divide,1,2),0)
+$(call math-expect-error,(call int_divide,0,0),division by zero is not allowed!)
+$(call math-expect-error,(call int_divide,1,0),division by zero is not allowed!)
+
+ifdef RUN_MATH_TESTS
+  ifdef MATH_TEST_FAILURE
+    math-tests:
+	@echo FAIL
+	@false
+  else
+    math-tests:
+	@echo PASS
+  endif
+  .PHONY: math-tests
+endif