refactoring!

src/arch.rs

@@ -0,0 +1,119 @@
+use std::simd::u64x2;
+use std::mem::{size_of, zeroed};
+
+use stack::Stack;
+
+extern "C" {
+  #[link_name = "lwut_bootstrap"]
+  pub fn bootstrap();
+  #[link_name = "lwut_swapcontext"]
+  pub fn swapcontext(save: *mut Registers, restore: *mut Registers);
+  #[link_name = "lwut_get_sp_limit"]
+  pub fn get_sp_limit() -> *const u8;
+  #[link_name = "lwut_set_sp_limit"]
+  pub fn set_sp_limit(limit: *const u8);
+  #[link_name = "lwut_abort"]
+  pub fn abort() -> !;
+}
+
+#[allow(non_camel_case_types)]
+pub type uintptr_t = u64;
+
+#[repr(C)]
+#[allow(dead_code)]
+pub struct Registers {
+  rbx: u64,
+  rsp: u64,
+  rbp: u64,
+  rdi: u64,
+  r12: u64,
+  r13: u64,
+  r14: u64,
+  r15: u64,
+  ip:  u64,
+  xmm0: u64x2,
+  xmm1: u64x2,
+  xmm2: u64x2,
+  xmm3: u64x2,
+  xmm4: u64x2,
+  xmm5: u64x2,
+}
+
+impl Registers {
+  pub fn new() -> Registers {
+    unsafe {
+      Registers {
+        ip: abort as u64,
+        .. zeroed()
+      }
+    }
+  }
+}
+
+macro_rules! into_regs_ {
+  ($regs:ident { $reg:ident } <- $iter:ident) => {
+    match $iter.next() {
+      Some(value) => {
+        $regs.$reg = *value;
+        Some($iter)
+      }
+      None => None
+    }
+  };
+  ($regs:ident { $reg:ident, $($regs_rest:ident),* } <- $iter:ident) => {
+    match $iter.next() {
+      Some(value) => {
+        $regs.$reg = *value;
+        into_regs_!($regs { $($regs_rest),* } <- $iter)
+      }
+      None => None
+    }
+  };
+}
+
+macro_rules! into_regs {
+  ($regs:ident { $($regs_rest:ident),* } <- $iter:expr) => {
+    {
+      let mut iter = $iter;
+      into_regs_!($regs { $($regs_rest),* } <- iter)
+    }
+  }
+}
+
+pub fn initialise_call_frame(stack: &mut Stack, init: uintptr_t, args: &[uintptr_t]) -> Registers {
+  let sp = stack.top() as *mut uintptr_t;
+  let sp = align_down_mut(sp, 16);
+  let sp = offset_mut(sp, -1);
+  unsafe {
+    *sp = 0;
+  }
+
+  let mut regs = Registers {
+    rbp: 0,
+    rsp: sp as uintptr_t,
+    ip: bootstrap as uintptr_t,
+    r12: init,
+    .. Registers::new()
+  };
+
+  match into_regs!(regs { rdi, r13, r14, r15 } <- args.iter()) {
+    Some(mut args) => if args.next().is_some() {
+      panic!("too many arguments")
+    },
+    None => {}
+  }
+
+  regs
+}
+
+#[inline]
+fn align_down_mut<T>(sp: *mut T, n: uint) -> *mut T {
+  let sp = (sp as uint) & !(n - 1);
+  sp as *mut T
+}
+
+// ptr::offset_mmut is positive ints only
+#[inline]
+pub fn offset_mut<T>(ptr: *mut T, count: int) -> *mut T {
+  (ptr as int + count * (size_of::<T>() as int)) as *mut T
+}

src/arch.s

@@ -2,7 +2,7 @@
 BITS 64
 
 ;; the structure containing every register that is saved on context switches.
-;; this needs to match the struct in context.rs, or shit will break badly.
+;; this needs to match the struct in arch.rs, or shit will break badly.
 struc context
   ctx_rbx resq 1
   ctx_rsp resq 1

src/context.rs

@@ -1,84 +1,38 @@
 use libc;
-use stack::Stack;
-use std::simd::u64x2;
-use std::mem::{zeroed, size_of, transmute};
+use std::mem::transmute;
 use std::raw;
 use fn_box::FnBox;
 
+use stack::Stack;
+use arch::{mod, Registers};
+
 pub struct Context {
   regs: Registers,
   stack: Stack
 }
 
-#[repr(C)]
-#[allow(dead_code)]
-struct Registers {
-  rbx: u64,
-  rsp: u64,
-  rbp: u64,
-  rdi: u64,
-  r12: u64,
-  r13: u64,
-  r14: u64,
-  r15: u64,
-  ip:  u64,
-  xmm0: u64x2,
-  xmm1: u64x2,
-  xmm2: u64x2,
-  xmm3: u64x2,
-  xmm4: u64x2,
-  xmm5: u64x2,
-}
-
-impl Registers {
-  fn zeroed() -> Registers { unsafe { zeroed() } }
-}
-
-extern "C" {
-  fn lwut_bootstrap();
-  fn lwut_swapcontext(save: *mut Registers, restore: *mut Registers);
-  fn lwut_get_sp_limit() -> *const u8;
-  fn lwut_set_sp_limit(limit: *const u8);
-  fn lwut_abort() -> !;
-}
-
 pub type BoxedFn<Args, Result> = Box<FnBox<Args, Result> + Send + 'static>;
 pub type StartFn<T, Args, Result> = fn(data: *mut T, f: BoxedFn<Args, Result>) -> !;
 
 impl Context {
   pub fn new<T, Args, Result>(init: StartFn<T, Args, Result>, data: *mut T,
                               f: BoxedFn<Args, Result>) -> Context {
-    let stack = Stack::new(4 << 20);
-
-    let sp = stack.top() as *mut uint;
-    let sp = align_down_mut(sp, 16);
-    let sp = offset_mut(sp, -1);
-    unsafe {
-      *sp = 0;
-    }
-
+    let mut stack = Stack::new(4 << 20);
     let f: raw::TraitObject = unsafe { transmute(f) };
 
     Context {
-      regs: Registers {
-        rbp: 0,
-        rsp: sp as libc::uintptr_t,
-        ip: lwut_bootstrap as libc::uintptr_t,
-        r12: lwut_init::<T, Args, Result> as libc::uintptr_t,
-        rdi: init as libc::uintptr_t,
-        r13: data as libc::uintptr_t,
-        r14: f.data as libc::uintptr_t,
-        r15: f.vtable as libc::uintptr_t,
-        // r8: …,
-        // r9: …,
-        .. Registers::zeroed()
-      },
+      regs: arch::initialise_call_frame(&mut stack,
+        init_ctx::<T, Args, Result> as libc::uintptr_t,
+        &[init as libc::uintptr_t,
+          data as libc::uintptr_t,
+          f.data as libc::uintptr_t,
+          f.vtable as libc::uintptr_t]),
       stack: stack
     }
   }
 }
 
-unsafe extern "C" fn lwut_init<T, A, R>(start: StartFn<T, A, R>, data: *mut T,
+unsafe extern "C" fn init_ctx<T, A, R>(start: StartFn<T, A, R>, data: *mut T,
                                        f_data: *mut (), f_vtable: *mut ()) -> ! {
   let f: BoxedFn<A, R> = transmute(raw::TraitObject {
     data: f_data,
@@ -91,30 +45,15 @@ unsafe extern "C" fn lwut_init<T, A, R>(start: StartFn<T, A, R>, data: *mut T,
 impl Context {
   pub unsafe fn native() -> Context {
     Context {
-      regs: Registers {
-        ip: lwut_abort as libc::uintptr_t,
-        .. Registers::zeroed()
-      },
-      stack: Stack::native(lwut_get_sp_limit())
+      regs: Registers::new(),
+      stack: Stack::native(arch::get_sp_limit())
     }
   }
 
 
   #[inline(always)]
   pub unsafe fn swap(out_context: &mut Context, in_context: &mut Context) {
-    lwut_set_sp_limit(in_context.stack.limit());
-    lwut_swapcontext(&mut out_context.regs, &mut in_context.regs);
+    arch::set_sp_limit(in_context.stack.limit());
+    arch::swapcontext(&mut out_context.regs, &mut in_context.regs);
   }
 }
-
-#[inline]
-fn align_down_mut<T>(sp: *mut T, n: uint) -> *mut T {
-  let sp = (sp as uint) & !(n - 1);
-  sp as *mut T
-}
-
-// ptr::offset_mmut is positive ints only
-#[inline]
-pub fn offset_mut<T>(ptr: *mut T, count: int) -> *mut T {
-  (ptr as int + count * (size_of::<T>() as int)) as *mut T
-}

src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(default_type_params)]
+#![feature(default_type_params, macro_rules)]
 extern crate libc;
 extern crate fn_box;
 
@@ -6,3 +6,6 @@ pub use context::Context;
 
 mod context;
 mod stack;
+
+mod arch;
+mod platform;

src/platform.rs

@@ -0,0 +1,8 @@
+use libc;
+
+extern "C" {
+  #[link_name = "lwut_stack_register"]
+  pub fn stack_register(start: *const u8, end: *const u8) -> libc::c_uint;
+  #[link_name = "lwut_stack_deregister"]
+  pub fn stack_deregister(id: libc::c_uint);
+}

src/stack.rs

@@ -1,4 +1,5 @@
 use libc;
+use platform;
 use std::ptr;
 use std::os::{errno, page_size, MemoryMap, MapReadable, MapWritable,
               MapNonStandardFlags};
@@ -17,11 +18,6 @@ pub enum Stack {
   }
 }
 
-extern "C" {
-  fn lwut_stack_register(start: *const u8, end: *const u8) -> libc::c_uint;
-  fn lwut_stack_deregister(id: libc::c_uint);
-}
-
 impl Stack {
   pub fn new(size: uint) -> Stack {
     let buf = match MemoryMap::new(size, &[MapReadable, MapWritable,
@@ -36,7 +32,7 @@ impl Stack {
     }
 
     let valgrind_id = unsafe {
-      lwut_stack_register(buf.data().offset(buf.len() as int) as *const _,
+      platform::stack_register(buf.data().offset(buf.len() as int) as *const _,
                                buf.data() as *const _)
     };
 
@@ -91,7 +87,7 @@ impl Drop for Stack {
     match *self {
       Stack::Native { .. } => {},
       Stack::Managed { valgrind_id, .. } => unsafe {
-        lwut_stack_deregister(valgrind_id);
+        platform::stack_deregister(valgrind_id);
       }
     }
   }