From d5e219dbf5ce69d6eac1f26eb7d1c590120952e3 Mon Sep 17 00:00:00 2001
From: hygienic-books <hygienic-books@tentic.net>
Date: Sat, 11 Nov 2023 01:17:14 +0100
Subject: [PATCH] feat(iso): Add bash-only CIDR calculator function (#21)

---
 setup.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/setup.sh b/setup.sh
index c6404b7..c606a9e 100644
--- a/setup.sh
+++ b/setup.sh
@@ -36,6 +36,17 @@ trap '[ "$?" -ne 77 ] || exit 77' ERR
 
 declare zpool_drive efi_drive boot_drive part_schema
 
+function calculate_prefix_from_netmask () {
+    # https://stackoverflow.com/a/50419919
+    c='0'
+    x='0'"$(printf -- '%o' ${1//./ })"
+    while [ "${x}" -gt '0' ]; do
+        # Modulo then bitwise-shift x and store as new x
+        let c+="$(( x % 2 ))" 'x>>=1'
+    done
+    printf -- '%s' '/'"${c}";
+}
+
 function setup_env_vars () {
     printf -- '%s\n' \
         'We will go over a series of questions to create an answer file with' \