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Refactor Doom modules to use native c"..." literals and remove duplicated cstr! macros #145

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sunsided merged 2 commits into from
May 23, 2026
Merged

Refactor Doom modules to use native c"..." literals and remove duplicated cstr! macros #145

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Initial plan
Copilot May 22, 2026
b5e3782
refactor: replace cstr! macro calls with c string literals
Copilot May 22, 2026
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79 changes: 34 additions & 45 deletions room/src/doom/d_iwad.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,17 +38,6 @@ const DIR_SEPARATOR: c_char = b'/' as c_char;
/// C string-joining functions.
const DIR_SEPARATOR_S: &[u8] = b"/\0";

/// Convenience macro that appends a null terminator to a string literal and
/// returns a `*mut c_char` pointer to it.
///
/// The resulting pointer points into the program's read-only data segment;
/// callers must never write through it.
macro_rules! cstr {
($s:literal) => {
concat!($s, "\0").as_ptr() as *mut c_char
};
}

extern "C" {
/// C standard `printf`; used to emit diagnostic messages during IWAD
/// search.
Expand Down Expand Up @@ -114,88 +103,88 @@ unsafe impl Sync for iwad_t {}
/// shareware releases. Mirrors `iwads[]` in `d_iwad.c`.
static IWADS: [iwad_t; 14] = [
iwad_t {
name: cstr!("doom2.wad"),
name: c"doom2.wad".as_ptr().cast_mut(),
mission: d_mode::doom2,
mode: d_mode::commercial,
description: cstr!("Doom II"),
description: c"Doom II".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("plutonia.wad"),
name: c"plutonia.wad".as_ptr().cast_mut(),
mission: d_mode::pack_plut,
mode: d_mode::commercial,
description: cstr!("Final Doom: Plutonia Experiment"),
description: c"Final Doom: Plutonia Experiment".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("tnt.wad"),
name: c"tnt.wad".as_ptr().cast_mut(),
mission: d_mode::pack_tnt,
mode: d_mode::commercial,
description: cstr!("Final Doom: TNT: Evilution"),
description: c"Final Doom: TNT: Evilution".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("doom.wad"),
name: c"doom.wad".as_ptr().cast_mut(),
mission: d_mode::doom,
mode: d_mode::retail,
description: cstr!("Doom"),
description: c"Doom".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("doom1.wad"),
name: c"doom1.wad".as_ptr().cast_mut(),
mission: d_mode::doom,
mode: d_mode::shareware,
description: cstr!("Doom Shareware"),
description: c"Doom Shareware".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("chex.wad"),
name: c"chex.wad".as_ptr().cast_mut(),
mission: d_mode::pack_chex,
mode: d_mode::shareware,
description: cstr!("Chex Quest"),
description: c"Chex Quest".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("hacx.wad"),
name: c"hacx.wad".as_ptr().cast_mut(),
mission: d_mode::pack_hacx,
mode: d_mode::commercial,
description: cstr!("Hacx"),
description: c"Hacx".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("freedm.wad"),
name: c"freedm.wad".as_ptr().cast_mut(),
mission: d_mode::doom2,
mode: d_mode::commercial,
description: cstr!("FreeDM"),
description: c"FreeDM".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("freedoom2.wad"),
name: c"freedoom2.wad".as_ptr().cast_mut(),
mission: d_mode::doom2,
mode: d_mode::commercial,
description: cstr!("Freedoom: Phase 2"),
description: c"Freedoom: Phase 2".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("freedoom1.wad"),
name: c"freedoom1.wad".as_ptr().cast_mut(),
mission: d_mode::doom,
mode: d_mode::retail,
description: cstr!("Freedoom: Phase 1"),
description: c"Freedoom: Phase 1".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("heretic.wad"),
name: c"heretic.wad".as_ptr().cast_mut(),
mission: d_mode::heretic,
mode: d_mode::retail,
description: cstr!("Heretic"),
description: c"Heretic".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("heretic1.wad"),
name: c"heretic1.wad".as_ptr().cast_mut(),
mission: d_mode::heretic,
mode: d_mode::shareware,
description: cstr!("Heretic Shareware"),
description: c"Heretic Shareware".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("hexen.wad"),
name: c"hexen.wad".as_ptr().cast_mut(),
mission: d_mode::hexen,
mode: d_mode::commercial,
description: cstr!("Hexen"),
description: c"Hexen".as_ptr().cast_mut(),
},
iwad_t {
name: cstr!("strife1.wad"),
name: c"strife1.wad".as_ptr().cast_mut(),
mission: d_mode::strife,
mode: d_mode::commercial,
description: cstr!("Strife"),
description: c"Strife".as_ptr().cast_mut(),
},
];

Expand Down Expand Up @@ -281,7 +270,7 @@ unsafe fn CheckDirectoryHasIWAD(dir: *mut c_char, iwadname: *mut c_char) -> *mut
return strdup(dir);
}

let filename = if strcmp(dir, cstr!(".")) == 0 {
let filename = if strcmp(dir, c".".as_ptr()) == 0 {
strdup(iwadname)
} else {
let strs: [*const c_char; 4] = [
Expand Down Expand Up @@ -386,7 +375,7 @@ unsafe fn IdentifyIWADByName(mut name: *mut c_char, mask: c_int) -> c_int {
/// `iwad_dirs_built` without synchronisation, and calls `AddIWADDir` which
/// imposes the same requirement.
unsafe fn BuildIWADDirList() {
AddIWADDir(cstr!("."));
AddIWADDir(c".".as_ptr().cast_mut());
iwad_dirs_built = true;
}

Expand Down Expand Up @@ -471,7 +460,7 @@ pub unsafe extern "C" fn D_TryFindWADByName(filename: *mut c_char) -> *mut c_cha
/// `mission` must be a valid, non-null pointer.
#[no_mangle]
pub unsafe extern "C" fn D_FindIWAD(mask: c_int, mission: *mut c_int) -> *mut c_char {
let iwadparm = M_CheckParmWithArgs(cstr!("-iwad"), 1);
let iwadparm = M_CheckParmWithArgs(c"-iwad".as_ptr(), 1);

if iwadparm != 0 {
let iwadfile = *myargv.offset((iwadparm + 1) as isize);
Expand Down Expand Up @@ -554,7 +543,7 @@ pub unsafe extern "C" fn D_SaveGameIWADName(gamemission: c_int) -> *mut c_char {
return IWADS[i].name;
}
}
cstr!("unknown.wad")
c"unknown.wad".as_ptr().cast_mut()
}

/// Returns the canonical IWAD filename that best matches `mission` and `mode`.
Expand All @@ -570,7 +559,7 @@ pub unsafe extern "C" fn D_SuggestIWADName(mission: c_int, mode: c_int) -> *mut
return IWADS[i].name;
}
}
cstr!("unknown.wad")
c"unknown.wad".as_ptr().cast_mut()
}

/// Returns a human-readable game name for the given `mission` and `mode`.
Expand All @@ -587,7 +576,7 @@ pub unsafe extern "C" fn D_SuggestGameName(mission: c_int, mode: c_int) -> *mut
return IWADS[i].description;
}
}
cstr!("Unknown game?")
c"Unknown game?".as_ptr().cast_mut()
}

/// Validates that the loaded IWAD matches the expected `_mission`.
Expand Down
30 changes: 10 additions & 20 deletions room/src/doom/d_mode.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -486,16 +486,6 @@ pub extern "C" fn D_IsEpisodeMap(mission: c_int) -> Boolean {
}
}

/// Convenience macro to produce a `*mut c_char` from a string literal.
///
/// Appends a NUL terminator and casts the resulting static byte slice to a raw
/// `c_char` pointer. Used only within [`D_GameMissionString`].
macro_rules! cstr {
($s:literal) => {
concat!($s, "\0").as_ptr() as *mut c_char
};
}

/// Return a NUL-terminated C string naming the given mission.
///
/// Returns one of `"doom"`, `"doom2"`, `"tnt"`, `"plutonia"`, `"hacx"`,
Expand All @@ -512,16 +502,16 @@ macro_rules! cstr {
#[no_mangle]
pub extern "C" fn D_GameMissionString(mission: c_int) -> *mut c_char {
match mission {
doom => cstr!("doom"),
doom2 => cstr!("doom2"),
pack_tnt => cstr!("tnt"),
pack_plut => cstr!("plutonia"),
pack_hacx => cstr!("hacx"),
pack_chex => cstr!("chex"),
heretic => cstr!("heretic"),
hexen => cstr!("hexen"),
strife => cstr!("strife"),
_ => cstr!("none"),
doom => c"doom".as_ptr().cast_mut(),
doom2 => c"doom2".as_ptr().cast_mut(),
pack_tnt => c"tnt".as_ptr().cast_mut(),
pack_plut => c"plutonia".as_ptr().cast_mut(),
pack_hacx => c"hacx".as_ptr().cast_mut(),
pack_chex => c"chex".as_ptr().cast_mut(),
heretic => c"heretic".as_ptr().cast_mut(),
hexen => c"hexen".as_ptr().cast_mut(),
strife => c"strife".as_ptr().cast_mut(),
_ => c"none".as_ptr().cast_mut(),
}
}

Expand Down
48 changes: 18 additions & 30 deletions room/src/doom/dstrings.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,8 @@
//! `Sync` by default, even though the pointers here only ever point at
//! immutable `'static` data.
//!
//! The `cstr!` macro appends `"\0"` at compile time and casts the resulting
//! `&str` to `*const c_char`, producing a valid NUL-terminated C string from
//! a Rust string literal without any heap allocation.
//! C string literals (`c"..."`) provide static NUL-terminated pointers without
//! heap allocation.
//!
//! The engine selects a message from these tables at random when the player
//! attempts to quit, using `gamemission` to pick the correct table
Expand Down Expand Up @@ -42,17 +41,6 @@ impl Ptr {
}
}

/// Construct a [`Ptr`] pointing to a NUL-terminated C string from a string literal.
///
/// The macro concatenates `"\0"` onto the literal at compile time, then casts
/// the `&'static str` data pointer to `*const c_char`. No heap allocation
/// occurs; the string resides in the binary's read-only data segment.
macro_rules! cstr {
($s:literal) => {
Ptr(concat!($s, "\0").as_ptr() as *const c_char)
};
}

/// Eight randomised quit messages shown when a Doom 1 player tries to exit.
///
/// Corresponds to `char *doom1_endmsg[]` in `dstrings.c`. The game picks
Expand All @@ -61,14 +49,14 @@ macro_rules! cstr {
/// equivalent) to access the table by its original symbol name.
#[no_mangle]
pub static doom1_endmsg: [Ptr; 8] = [
cstr!("are you sure you want to\nquit this great game?"),
cstr!("please don't leave, there's more\ndemons to toast!"),
cstr!("let's beat it -- this is turning\ninto a bloodbath!"),
cstr!("i wouldn't leave if i were you.\ndos is much worse."),
cstr!("you're trying to say you like dos\nbetter than me, right?"),
cstr!("don't leave yet -- there's a\ndemon around that corner!"),
cstr!("ya know, next time you come in here\ni'm gonna toast ya."),
cstr!("go ahead and leave. see if i care."),
Ptr(c"are you sure you want to\nquit this great game?".as_ptr()),
Ptr(c"please don't leave, there's more\ndemons to toast!".as_ptr()),
Ptr(c"let's beat it -- this is turning\ninto a bloodbath!".as_ptr()),
Ptr(c"i wouldn't leave if i were you.\ndos is much worse.".as_ptr()),
Ptr(c"you're trying to say you like dos\nbetter than me, right?".as_ptr()),
Ptr(c"don't leave yet -- there's a\ndemon around that corner!".as_ptr()),
Ptr(c"ya know, next time you come in here\ni'm gonna toast ya.".as_ptr()),
Ptr(c"go ahead and leave. see if i care.".as_ptr()),
];

/// Eight randomised quit messages shown when a Doom 2 player tries to exit.
Expand All @@ -78,14 +66,14 @@ pub static doom1_endmsg: [Ptr; 8] = [
/// `gamemission` is `doom2`, `pack_tnt`, or `pack_plut`.
#[no_mangle]
pub static doom2_endmsg: [Ptr; 8] = [
cstr!("are you sure you want to\nquit this great game?"),
cstr!("you want to quit?\nthen, thou hast lost an eighth!"),
cstr!("don't go now, there's a \ndimensional shambler waiting\nat the dos prompt!"),
cstr!("get outta here and go back\nto your boring programs."),
cstr!("if i were your boss, i'd \n deathmatch ya in a minute!"),
cstr!("look, bud. you leave now\nand you forfeit your body count!"),
cstr!("just leave. when you come\nback, i'll be waiting with a bat."),
cstr!("you're lucky i don't smack\nyou for thinking about leaving."),
Ptr(c"are you sure you want to\nquit this great game?".as_ptr()),
Ptr(c"you want to quit?\nthen, thou hast lost an eighth!".as_ptr()),
Ptr(c"don't go now, there's a \ndimensional shambler waiting\nat the dos prompt!".as_ptr()),
Ptr(c"get outta here and go back\nto your boring programs.".as_ptr()),
Ptr(c"if i were your boss, i'd \n deathmatch ya in a minute!".as_ptr()),
Ptr(c"look, bud. you leave now\nand you forfeit your body count!".as_ptr()),
Ptr(c"just leave. when you come\nback, i'll be waiting with a bat.".as_ptr()),
Ptr(c"you're lucky i don't smack\nyou for thinking about leaving.".as_ptr()),
];

#[cfg(test)]
Expand Down
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