load and jump to stage 3 separately from stage 2
pantonshire
8 months ago
parent
da529e8426
commit
bb60e1c8ed
@ -0,0 +1,69 @@
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[bits 16]
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%include "fn.s"
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%include "layout.s"
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%include "globals.s"
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%include "s2_fns.s"
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extern s2_data.s3_bin_offset_sectors
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extern s2_data.s3_bin_len_sectors
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load_s3:
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fnstart
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push ebx
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; Calculate the stage 3 start LBA.
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mov ax, [REAL_GLOBALS + STAGE_2_START_LBA]
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add ax, [s2_data.s3_bin_offset_sectors]
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jc .fail
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; Stage 3 should not overlap with stage 2.
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cmp word [REAL_GLOBALS + STAGE_2_END_LBA], ax
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jae .fail
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xor ebx, ebx
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; There must be at least one sector to load.
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mov bx, [s2_data.s3_bin_len_sectors]
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or bx, bx
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jz .fail
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; Calculate the end LBA (inclusive).
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dec bx
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add bx, ax
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jc .fail
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; Check stage 3 is entirely inside the partition.
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cmp dword [REAL_GLOBALS + LOADER_PART_END_LBA], ebx
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jb .fail
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push ax ; Current LBA
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push bx ; s3 end LBA
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mov ebx, S3_LOAD_ADDR ; Current load address
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.load_loop:
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mov ax, [bp - 0x06] ; Load current LBA
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cmp word [bp - 0x08], ax ; Compare to s3 end LBA
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jb .load_done
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mov ecx, ebx
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call read_sector
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jc .fail
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add ebx, 512
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inc word [bp - 0x06]
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jmp .load_loop
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.load_done:
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add sp, 4
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pop ebx
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clc
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fnret
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.fail:
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pop ebx
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stc
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fnret
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global load_s3
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@ -1,213 +1,6 @@
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use std::{env, ffi::{OsStr, OsString}, fmt, fs, io, path::{Path, PathBuf}, process::{self, Command}};
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fn main() {
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let out_dir = env::var_os("OUT_DIR")
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.expect("OUT_DIR not set");
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let out_dir = PathBuf::from(out_dir);
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let search_path = SearchPath::load();
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const LINKER_SCRIPT_PATH: &str = "link.ld";
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let nasm_path = search_path.search("nasm")
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.next()
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.expect("failed to find nasm in PATH");
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let nasm = Nasm::new(nasm_path);
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build_asm(&nasm, &out_dir);
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emit_link_args();
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rerun_if_changed("build.rs".as_ref());
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}
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fn emit_link_args() {
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let linker_script_path = "link.ld";
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println!("cargo::rustc-link-arg=-T{}", linker_script_path);
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rerun_if_changed(linker_script_path.as_ref());
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}
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fn rerun_if_changed(path: &Path) {
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let path_str = path.to_str()
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.expect("expected path to be valid utf8");
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println!("cargo::rerun-if-changed={}", path_str);
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}
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fn link_obj(path: &Path) {
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let path_str = path.to_str()
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.expect("expected path to be valid utf8");
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println!("cargo::rustc-link-arg={}", path_str);
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}
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fn build_asm(nasm: &Nasm, out_dir: &Path) {
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let asm_srcs = fs::read_dir("src/asm")
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.expect("failed to get asm sources");
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for asm_src in asm_srcs {
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let asm_src = asm_src.expect("failed to get asm source");
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let ty = asm_src.file_type().expect("failed to get file type");
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if !ty.is_file() {
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continue;
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}
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let src_path = asm_src.path();
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let is_asm = src_path
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.extension()
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.map(|ext| ext == "s")
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.unwrap_or(false);
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if !is_asm {
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continue;
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}
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let out_filename = src_path
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.file_name()
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.unwrap()
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.apply(PathBuf::from)
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.with_extension("o");
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let out_path = out_dir.join(out_filename);
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nasm.assemble(
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&out_path,
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&[&src_path],
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&["../include".as_ref()]
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).expect("failed to assemble");
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link_obj(&out_path);
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}
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}
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struct Nasm {
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bin_path: PathBuf,
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}
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impl Nasm {
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fn new(bin_path: PathBuf) -> Self {
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Self { bin_path }
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}
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fn assemble(&self, output: &Path, sources: &[&Path], includes: &[&Path]) -> Result<(), CmdError>
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{
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for source in sources {
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rerun_if_changed(source);
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}
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let mut cmd = Command::new(&self.bin_path);
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cmd
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.arg("-Werror")
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.arg("-f")
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.arg("elf");
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for include in includes {
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let mut buf = OsString::new();
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buf.push("-I");
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buf.push(include);
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cmd.arg(buf);
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}
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cmd
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.arg("-o")
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.arg(output)
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.args(sources);
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run_cmd(&mut cmd)?;
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Ok(())
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}
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}
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struct SearchPath {
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paths: Vec<PathBuf>
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}
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impl SearchPath {
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fn load() -> Self {
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let path_var = env::var_os("PATH").unwrap_or_default();
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let paths = env::split_paths(&path_var).collect();
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Self { paths }
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}
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fn search<'a, 'b, 'c, T>(&'a self, bin: &'b T) -> impl Iterator<Item = PathBuf> + 'c
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where
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'a: 'c,
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'b: 'c,
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T: AsRef<OsStr> + ?Sized,
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{
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let bin = bin.as_ref();
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self.paths
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.iter()
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.filter_map(move |path| {
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let path = path.join(bin);
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fs::metadata(&path)
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.ok()
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.and_then(|meta| if meta.is_file() || meta.is_symlink() {
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Some(path)
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} else {
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None
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})
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})
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}
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}
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fn run_cmd(cmd: &mut Command) -> Result<process::Output, CmdError> {
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use fmt::Write;
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cmd
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.output()
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.map_err(CmdErrorKind::Io)
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.and_then(|out| if out.status.success() {
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Ok(out)
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} else {
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Err(CmdErrorKind::Status(out))
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})
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.map_err(|err| {
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let mut cmd_buf = String::new();
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write!(&mut cmd_buf, "{:?}", cmd).ok();
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CmdError::new(cmd_buf, err)
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})
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}
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#[derive(Debug)]
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struct CmdError {
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cmd: String,
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kind: CmdErrorKind,
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}
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impl CmdError {
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fn new(cmd: String, kind: CmdErrorKind) -> Self {
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Self { cmd, kind }
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}
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}
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impl fmt::Display for CmdError {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "`{}` failed: ", self.cmd)?;
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match &self.kind {
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CmdErrorKind::Io(err) => err.fmt(f),
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CmdErrorKind::Status(out) => write!(f, "exited with status {}", out.status),
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}
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}
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}
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#[derive(Debug)]
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enum CmdErrorKind {
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Io(io::Error),
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Status(process::Output),
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}
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trait Apply: Sized {
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fn apply<T, F>(self, f: F) -> T
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where
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F: FnOnce(Self) -> T;
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}
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impl<U> Apply for U
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where
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U: Sized,
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{
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fn apply<T, F>(self, f: F) -> T
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where
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F: FnOnce(Self) -> T
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{
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f(self)
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}
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println!("cargo::rerun-if-changed={}", LINKER_SCRIPT_PATH);
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println!("cargo::rustc-link-arg=-T{}", LINKER_SCRIPT_PATH);
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}
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@ -0,0 +1,7 @@
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.code32
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.section ".trampoline", "ax", @progbits
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trampoline:
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jmp _start
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.globl trampoline
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@ -1,11 +0,0 @@
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pub mod flags {
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pub const CF: u32 = 1 << 0;
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pub const PF: u32 = 1 << 2;
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pub const AF: u32 = 1 << 4;
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pub const ZF: u32 = 1 << 6;
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pub const SF: u32 = 1 << 7;
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pub const TF: u32 = 1 << 8;
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pub const IF: u32 = 1 << 9;
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pub const DF: u32 = 1 << 10;
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pub const OF: u32 = 1 << 11;
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}
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