add support for 32-bit ARM on Windows (#477)

* add support for 32-bit ARM on Windows

* fix mismatched brace in appveyor.yml

* remove arm platform from appveyor.yml for now

* fix arm build

* fix typo

* fix assembler names

* try Visual Studio 2017

* add windows arm32 to .appveyor.yml

* update README.md

msvcc.sh

@@ -60,7 +60,7 @@ do
   case $1
   in
     --verbose)
-      $verbose=1
+      verbose=1
       shift 1
     ;;
     --version)
@@ -80,6 +80,11 @@ do
       safeseh=
       shift 1
     ;;
+    -marm)
+      ml='armasm'
+      safeseh=
+      shift 1
+    ;;
     -clang-cl)
       cl="clang-cl"
       shift 1
@@ -237,6 +242,7 @@ do
       else
         output="-Fe$2"
       fi
+      armasm_output="-o $2"
       if [ -n "$assembly" ]; then
         args="$args $output"
       else
@@ -289,13 +295,21 @@ if [ -n "$assembly" ]; then
     fi
     ppsrc="$outdir/$(basename $src|sed 's/.S$/.asm/g')"
 
+    if [ $ml = "armasm" ]; then
+      defines="$defines -D_M_ARM"
+    fi
+
     if test -n "$verbose"; then
       echo "$cl -nologo -EP $includes $defines $src > $ppsrc"
     fi
 
     "$cl" -nologo -EP $includes $defines $src > $ppsrc || exit $?
     output="$(echo $output | sed 's%/F[dpa][^ ]*%%g')"
-    args="-nologo $safeseh $single $output $ppsrc"
+    if [ $ml = "armasm" ]; then
+      args="-nologo -g -oldit $armasm_output $ppsrc -errorReport:prompt"
+    else
+      args="-nologo $safeseh $single $output $ppsrc"
+    fi
 
     if test -n "$verbose"; then
       echo "$ml $args"