Guess section alignment & write __ArenaHi in .lcf

assets/ldscript.lcf

@@ -1,6 +1,6 @@
 MEMORY
 {
-    text : origin = 0x80003100
+    text : origin = $ORIGIN
 }
 
 SECTIONS
@@ -16,7 +16,7 @@ SECTIONS
     _db_stack_addr = (_stack_addr + 0x2000);
     _db_stack_end = _stack_addr;
     __ArenaLo = (_db_stack_addr + 0x1f) & ~0x1f;
-    __ArenaHi = 0x81700000;
+    __ArenaHi = $ARENAHI;
 }
 
 FORCEFILES

src/util/lcf.rs

@@ -1,20 +1,46 @@
 use std::path::PathBuf;
 
-use anyhow::Result;
+use anyhow::{bail, Result};
 use itertools::Itertools;
 
 use crate::obj::ObjInfo;
 
+#[inline]
+const fn align_up(value: u32, align: u32) -> u32 { (value + (align - 1)) & !(align - 1) }
+
 pub fn generate_ldscript(obj: &ObjInfo, auto_force_files: bool) -> Result<String> {
+    let origin = obj.sections.iter().map(|s| s.address).min().unwrap();
     let stack_size = match (obj.stack_address, obj.stack_end) {
         (Some(stack_address), Some(stack_end)) => stack_address - stack_end,
         _ => 65535, // default
     };
 
+    // Guess section alignment
+    let mut alignments = Vec::with_capacity(obj.sections.len());
+    let mut last_section_end = origin as u32;
+    for section in &obj.sections {
+        let section_start = section.address as u32;
+        let mut align = 0x20;
+        while align_up(last_section_end, align) < section_start {
+            align = (align + 1).next_power_of_two();
+        }
+        if align_up(last_section_end, align) != section_start {
+            bail!(
+                "Couldn't determine alignment for section '{}' ({:#010X} -> {:#010X})",
+                section.name,
+                last_section_end,
+                section_start
+            );
+        }
+        last_section_end = section_start + section.size as u32;
+        alignments.push(align);
+    }
+
     let section_defs = obj
         .sections
         .iter()
-        .map(|s| format!("{} ALIGN({:#X}):{{}}", s.name, 0x20 /* TODO */))
+        .zip(alignments)
+        .map(|(s, align)| format!("{} ALIGN({:#X}):{{}}", s.name, align))
         .join("\n        ");
 
     let mut force_files = Vec::with_capacity(obj.link_order.len());
@@ -35,15 +61,17 @@ pub fn generate_ldscript(obj: &ObjInfo, auto_force_files: bool) -> Result<String
     let last_section_symbol = format!("_f_{}", last_section_name.trim_start_matches('.'));
 
     let mut out = include_str!("../../assets/ldscript.lcf")
-        .replacen("$SECTIONS", &section_defs, 1)
+        .replace("$ORIGIN", &format!("{:#X}", origin))
+        .replace("$SECTIONS", &section_defs)
         .replace("$LAST_SECTION_SYMBOL", &last_section_symbol)
         .replace("$LAST_SECTION_NAME", &last_section_name)
-        .replacen("$STACKSIZE", &format!("{:#X}", stack_size), 1)
+        .replace("$STACKSIZE", &format!("{:#X}", stack_size))
-        .replacen("$FORCEACTIVE", &force_active.join("\n    "), 1);
+        .replace("$FORCEACTIVE", &force_active.join("\n    "))
+        .replace("$ARENAHI", &format!("{:#X}", obj.arena_hi.unwrap_or(0x81700000)));
     out = if auto_force_files {
-        out.replacen("$FORCEFILES", &force_files.join("\n    "), 1)
+        out.replace("$FORCEFILES", &force_files.join("\n    "))
     } else {
-        out.replacen("$FORCEFILES", "", 1)
+        out.replace("$FORCEFILES", "")
     };
     Ok(out)
 }