From d9fc333644d825020903b3e64b79de7a5278f151 Mon Sep 17 00:00:00 2001
From: Gwilym Inzani <email@gwilym.dev>
Date: Wed, 26 Jul 2023 10:21:54 +0100
Subject: [PATCH] Implement the padding flag

---
 agb-gbafix/src/lib.rs  | 16 ++++++++++++++--
 agb-gbafix/src/main.rs | 13 ++++++++++---
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/agb-gbafix/src/lib.rs b/agb-gbafix/src/lib.rs
index 7d65b6d2..36b0389f 100644
--- a/agb-gbafix/src/lib.rs
+++ b/agb-gbafix/src/lib.rs
@@ -60,7 +60,19 @@ impl GbaHeader {
     }
 }
 
-pub fn write_gba_file<W: Write>(input: &[u8], mut header: GbaHeader, output: &mut W) -> Result<()> {
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub enum PaddingBehaviour {
+    Pad,
+    #[default]
+    DoNotPad,
+}
+
+pub fn write_gba_file<W: Write>(
+    input: &[u8],
+    mut header: GbaHeader,
+    padding_behaviour: PaddingBehaviour,
+    output: &mut W,
+) -> Result<()> {
     let elf_file = elf::ElfBytes::<elf::endian::AnyEndian>::minimal_parse(input)?;
 
     let section_headers = elf_file
@@ -111,7 +123,7 @@ pub fn write_gba_file<W: Write>(input: &[u8], mut header: GbaHeader, output: &mu
         bytes_written += data.len() as u64;
     }
 
-    if !bytes_written.is_power_of_two() {
+    if !bytes_written.is_power_of_two() && padding_behaviour == PaddingBehaviour::Pad {
         let required_padding = bytes_written.next_power_of_two() - bytes_written;
 
         for _ in 0..required_padding {
diff --git a/agb-gbafix/src/main.rs b/agb-gbafix/src/main.rs
index 94a7c697..3ae0f25c 100644
--- a/agb-gbafix/src/main.rs
+++ b/agb-gbafix/src/main.rs
@@ -7,7 +7,7 @@ use std::{
     path::PathBuf,
 };
 
-use agb_gbafix::{write_gba_file, GbaHeader};
+use agb_gbafix::{write_gba_file, GbaHeader, PaddingBehaviour};
 
 fn main() -> Result<()> {
     let matches = clap::Command::new("agb-gbafix")
@@ -18,7 +18,7 @@ fn main() -> Result<()> {
         .arg(arg!(-c --gamecode <GAME_CODE> "Sets the game code, 4 bytes"))
         .arg(arg!(-m --makercode <MAKER_CODE> "Set the maker code, 2 bytes"))
         .arg(arg!(-r --gameversion <VERSION> "Set the version of the game, 0-255").value_parser(value_parser!(u8)))
-        .arg(arg!(-p --padding "Ignored for compatibility with gbafix"))
+        .arg(arg!(-p --padding "Pad the ROM to the next power of 2 in size"))
         .get_matches();
 
     let input = matches.get_one::<PathBuf>("INPUT").unwrap();
@@ -70,10 +70,17 @@ fn main() -> Result<()> {
         }
     }
 
+    let pad = matches.get_flag("padding");
+    let pad = if pad {
+        PaddingBehaviour::Pad
+    } else {
+        PaddingBehaviour::DoNotPad
+    };
+
     let mut output = BufWriter::new(fs::File::create(output)?);
     let file_data = fs::read(input)?;
 
-    write_gba_file(file_data.as_slice(), header, &mut output)?;
+    write_gba_file(file_data.as_slice(), header, pad, &mut output)?;
 
     output.flush()?;