[Makefile][System ID] Improved method for detecting OS

make/system-id.mk

@@ -1,47 +1,52 @@
 # shared.mk
 #
 # environment variables common to all operating systems supported by the make system
+# C.f. https://gist.github.com/sighingnow/deee806603ec9274fd47
 
-# Make sure we know a few things about the architecture 
-UNAME := $(shell uname)
-ARCH := $(shell uname -m)
-ifneq (,$(filter $(ARCH), x86_64 amd64))
-  X86-64 := 1
-  X86_64 := 1
-  AMD64 := 1
-endif
+OSFLAG :=
 
-# configure some variables dependent upon what type of system this is
-
-# Linux
-ifeq ($(UNAME), Linux)
-  OSFAMILY := linux
-  LINUX := 1
-endif
-
-# Mac OSX
-ifeq ($(UNAME), Darwin)
-  OSFAMILY := macos
-  MACOS := 1
-endif
-
-# Windows using MinGW shell
-ifeq (MINGW, $(findstring MINGW,$(UNAME)))
-  OSFAMILY := windows
-  MINGW := 1
-  WINDOWS := 1
-endif
-
-# Windows using Cygwin shell
-ifeq (CYGWIN ,$(findstring CYGWIN,$(UNAME)))
+ifeq ($(OS),Windows_NT)
+  OSFLAG += -D WIN32
   OSFAMILY := windows
   WINDOWS := 1
-  CYGWIN := 1
+
+  ifeq ($(PROCESSOR_ARCHITECTURE),AMD64)
+    OSFLAG += -D AMD64
+  endif
+  ifeq ($(PROCESSOR_ARCHITECTURE),x86)
+    OSFLAG += -D IA32
+  endif
+else
+  UNAME_S := $(shell uname -s)
+  ifeq ($(UNAME_S),Linux)
+    OSFLAG += -D LINUX
+    OSFAMILY := linux
+    LINUX := 1
+  endif
+
+  ifeq ($(UNAME_S),Darwin)
+    OSFLAG += -D OSX
+    OSFAMILY := macos
+    MACOS := 1
+  endif
+
+  UNAME_P := $(shell uname -p)
+  ifeq ($(UNAME_P),x86_64)
+    OSFLAG += -D AMD64
+  endif
+
+  ifneq ($(filter %86,$(UNAME_P)),)
+  OSFLAG += -D IA32
+  endif
+
+  ifneq ($(filter arm%,$(UNAME_P)),)
+    OSFLAG += -D ARM
+  endif
 endif
 
 # report an error if we couldn't work out what OS this is running on
 ifndef OSFAMILY
   $(info uname reports $(UNAME))
   $(info uname -m reports $(ARCH))
-  $(error failed to detect operating system)  
+  $(error failed to detect operating system)
 endif