From b16ec83a33f52e44a72bd464aa08128f44e915d4 Mon Sep 17 00:00:00 2001
From: ISSOtm <eldredhabert0@gmail.com>
Date: Thu, 30 Jan 2020 02:43:31 +0100
Subject: [PATCH] Add `gbdiff.bash` script
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This script allows diffing two Game Boy ROMs using `xxd` and `diff` and
attempts to augment the diff using information pulled from SYM files.
It's not part of RGBDS proper, but can be useful to debug tests (when ROMs fail
to match).
---
 contrib/gbdiff.bash | 71 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100755 contrib/gbdiff.bash

diff --git a/contrib/gbdiff.bash b/contrib/gbdiff.bash
new file mode 100755
index 00000000..39014040
--- /dev/null
+++ b/contrib/gbdiff.bash
@@ -0,0 +1,71 @@
+#!/bin/bash
+
+# SPDX-License-Identifier: MIT
+#
+# Copyright (c) 2020 Eldred Habert
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+STATE=0
+diff <(xxd $1) <(xxd $2) | while read -r LINE; do
+	if [ $STATE -eq 0 ]; then
+		# Discard first line (line info)
+		STATE=1
+	elif [ "$LINE" = '---' ]; then
+		# Separator between files switches states
+		echo $LINE
+		STATE=3
+	elif echo $LINE | grep -Eq '^[0-9]+(,[0-9]+)?c[0-9]+(,[0-9]+)?'; then
+		# Line info resets the whole thing
+		STATE=1
+	elif [ $STATE -eq 1  -o  $STATE -eq 3 ]; then
+		# Compute the GB address from the ROM offset
+		OFS=$(echo $LINE | cut -d ' ' -f 2 | tr -d ':')
+		BANK=$((0x$OFS / 0x4000))
+		ADDR=$((0x$OFS % 0x4000 + ($BANK != 0) * 0x4000))
+		# Try finding the preceding symbol closest to the diff
+		if [ $STATE -eq 1 ]; then
+			STATE=2
+			SYMFILE=$(echo $1 | cut -d '.' -f 1).sym
+		else
+			STATE=4
+			SYMFILE=$(echo $2 | cut -d '.' -f 1).sym
+		fi
+		EXTRA=$(if [ -f "$SYMFILE" ]; then
+			# Read the sym file for such a symbol
+			# Ignore comment lines, only pick matching bank
+			grep -Fv ';' "$SYMFILE" |
+			 grep -Ei $(printf "^%02x:" $BANK) |
+			 while read -r SYMADDR SYM; do
+				SYMADDR=$((0x$(echo $SYMADDR | cut -d ':' -f 2)))
+				if [ $SYMADDR -le $ADDR ]; then
+					printf " (%s+%#x)\n" $SYM $(($ADDR - $SYMADDR))
+				fi
+			# TODO: assumes sorted sym files
+			done | tail -n 1
+		fi)
+		printf "%02x:%04x %s\n" $BANK $ADDR $EXTRA
+	fi
+	if [ $STATE -eq 2  -o  $STATE -eq 4 ]; then
+		OFS=$(echo $LINE | cut -d ' ' -f 2 | tr -d ':')
+		BANK=$((0x$OFS / 0x4000))
+		ADDR=$((0x$OFS % 0x4000 + ($BANK != 0) * 0x4000))
+		printf "%s %02x:%04x: %s\n" "$(echo $LINE | cut -d ' ' -f 1)" $BANK $ADDR "$(echo $LINE | cut -d ' ' -f 3-)"
+	fi
+done