Support both cpu platforms for macOS

configure

@@ -46,10 +46,16 @@ if [ "${arch}" = "x86_64" ]; then
     echo "Setting up compilation for a ${platform} 64-bit system"
     sed -e"s/@config@/blpapi3_64/" src/Makevars.in > src/Makevars
     flavour="64"
+    if [ "${platform}" = "osx" ]; then
+        cpu="x86"
+    fi
 elif [ "${arch}" = "arm64" ]; then
     echo "Setting up compilation for a ${platform} 64-bit system"
     sed -e"s/@config@/blpapi3_64/" src/Makevars.in > src/Makevars
     flavour="64"
+    if [ "${platform}" = "osx" ]; then
+        cpu="arm"
+    fi
 elif [ "${arch}" = "i686" ]; then
     echo "Setting up compilation for a ${platform} 32-bit system"
     sed -e"s/@config@/blpapi3_32/" src/Makevars.in > src/Makevars
@@ -80,7 +86,7 @@ download() {
 #: ${blpBranch="master"}
 : ${blpBranch="feature/release_3.24.6.1"}
 
-## Check for header files and download if needed
+## Check for header files and download if needed, this looks at repo blp in directory headers/
 cwd=$(pwd)
 mkdir -p blp/${platform}
 cd blp/${platform}
@@ -92,11 +98,13 @@ fi
 tar xfz ${blpHeaders} -C ../../inst
 cd ${cwd}
 
-## Get and install precompiled shared library
+## Get and install precompiled shared library, this looks at repo blp in directoris 'PlatformFlavourCpu'
+## Here flavour is mostly redundant as of 2024 as 32 bit is no longer built at CRAN but we support user who may have it
+## The Cpu tag is used only on macos and it used to distinguish between (old) x86_64 and newer arm64
 mkdir -p inst/blp
 cd blp/${platform}
 if [ ! -f ${blpLibrary} ]; then
-    download https://github.com/Rblp/blp/raw/${blpBranch}/${platform}${flavour}/blpLibrary.tar.gz
+    download https://github.com/Rblp/blp/raw/${blpBranch}/${platform}${flavour}${cpu}/blpLibrary.tar.gz
 else
     echo "** using ${blpLibrary}"
 fi