Add gbdiff.sh from rgbds

tools/gbdiff.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+
+# Usage: tools/gbdiff.sh baserom.gbc project.gbc
+
+# Copyright (c) 2020, Eldred Habert.
+# SPDX-License-Identifier: MIT
+
+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 "$LINE"
+		STATE=3
+	elif grep -Eq '^[0-9]+(,[0-9]+)?[cd][0-9]+(,[0-9]+)?' <<< "$LINE"; then
+		# Line info resets the whole thing
+		STATE=1
+	elif [[ $STATE -eq 1  ||  $STATE -eq 3 ]]; then
+		# Compute the GB address from the ROM offset
+		OFS=$(cut -d ' ' -f 2 <<< "$LINE" | tr -d ':')
+		BANK=$((0x$OFS / 0x4000))
+		ADDR=$((0x$OFS % 0x4000 + (BANK != 0) * 0x4000))
+		# Try finding the preceding symbol closest to the diff
+		if [[ $STATE -eq 1 ]]; then
+			STATE=2
+			SYMFILE=${1%.*}.sym
+		else
+			STATE=4
+			SYMFILE=${2%.*}.sym
+		fi
+		EXTRA=$(if [[ -f "$SYMFILE" ]]; then
+			# Read the sym file for such a symbol
+			# Ignore comment lines, only pick matching bank
+			# (The bank regex ignores comments already, make `cut` and `tr` process less lines)
+			grep -Ei "$(printf "^%02x:" $BANK)" "$SYMFILE" |
+			 cut -d ';' -f 1 |
+			 tr -d "\r" |
+			 while read -r SYMADDR SYM; do
+				SYMADDR=$((0x${SYMADDR#*:}))
+				if [[ $SYMADDR -le $ADDR ]]; then
+					printf " (%s+0x%x)\n" "$SYM" $((ADDR - SYMADDR))
+				fi
+			# Assumes sorted sym files
+			done | tail -n 1
+		fi)
+		printf "%02x:%04x %s\n" $BANK $ADDR "$EXTRA"
+	fi
+	if [[ $STATE -eq 2  ||  $STATE -eq 4 ]]; then
+		OFS=$(cut -d ' ' -f 2 <<< "$LINE" | tr -d ':')
+		BANK=$((0x$OFS / 0x4000))
+		ADDR=$((0x$OFS % 0x4000 + (BANK != 0) * 0x4000))
+		printf "%s %02x:%04x: %s\n" "${LINE:0:1}" $BANK $ADDR "${LINE#*: }"
+	fi
+done