Add a contrib script for visualising the generated palettes as a PNG

contrib/view_palettes.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+set -euo pipefail
+
+if [[ $# -ne 2 ]]; then
+	cat <<EOF >&2
+Usage: $0 <palettes.pal> <output.png>
+EOF
+	exit 1
+fi
+
+TMP=$(mktemp -d)
+readonly TMP
+trap 'rm -rf "$TMP"' EXIT
+
+tile() { for i in {0..7}; do printf "$1"; done }
+{ tile '\x00\x00' && tile '\xFF\x00' && tile '\x00\xFF' && tile '\xFF\xFF'; } >"$TMP/tmp.2bpp"
+
+NB_BYTES=$(wc -c <"$1")
+(( NB_PALS = NB_BYTES / 8 ))
+for (( i = 0; i < NB_PALS; i++ )); do
+	printf '\0\1\2\3' >>"$TMP/tmp.tilemap"
+	printf $(printf '\\x%x' $i{,,,}) >> "$TMP/tmp.palmap"
+done
+
+"${RGBGFX:-${RGBDS+$RGBDS/}rgbgfx}" -r 4 "$2" -o "$TMP/tmp.2bpp" -OTQ -p "$1" -n "$NB_PALS"