Rename Stack::top() to Stack::base(), which is correct.

Fixes #25.

src/arch/x86.rs

@@ -84,7 +84,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
     *sp.0 = val
   }
 
-  let mut sp = StackPointer(stack.top() as *mut usize);
+  let mut sp = StackPointer(stack.base() as *mut usize);
   push(&mut sp, 0xdead0cfa); // CFA slot
   push(&mut sp, f as usize); // function
   push(&mut sp, trampoline_1 as usize);
@@ -96,7 +96,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
 pub unsafe fn swap(arg: usize, old_sp: &mut StackPointer, new_sp: &StackPointer,
                    new_stack: &Stack) -> usize {
   // Address of the topmost CFA stack slot.
-  let new_cfa = (new_stack.top() as *mut usize).offset(-1);
+  let new_cfa = (new_stack.base() as *mut usize).offset(-1);
 
   #[naked]
   unsafe extern "C" fn trampoline() {

src/arch/x86_64.rs

@@ -85,7 +85,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
     *sp.0 = val
   }
 
-  let mut sp = StackPointer(stack.top() as *mut usize);
+  let mut sp = StackPointer(stack.base() as *mut usize);
   push(&mut sp, 0xdeaddeaddead0cfa); // CFA slot
   push(&mut sp, 0 as usize); // alignment
   push(&mut sp, f as usize); // function
@@ -98,7 +98,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
 pub unsafe fn swap(arg: usize, old_sp: &mut StackPointer, new_sp: &StackPointer,
                    new_stack: &Stack) -> usize {
   // Address of the topmost CFA stack slot.
-  let new_cfa = (new_stack.top() as *mut usize).offset(-1);
+  let new_cfa = (new_stack.base() as *mut usize).offset(-1);
 
   #[naked]
   unsafe extern "C" fn trampoline() {

src/debug/valgrind.rs

@@ -12,7 +12,7 @@ pub struct StackId(self::valgrind::Value);
 impl StackId {
   #[inline(always)]
   pub fn register<Stack: stack::Stack>(stack: &Stack) -> StackId {
-    StackId(stack_register(stack.limit(), stack.top()))
+    StackId(stack_register(stack.limit(), stack.base()))
   }
 }
 

src/os/mod.rs

@@ -51,7 +51,7 @@ impl Stack {
 
 impl stack::Stack for Stack {
   #[inline(always)]
-  fn top(&self) -> *mut u8 {
+  fn base(&self) -> *mut u8 {
     unsafe {
       self.ptr.offset(self.len as isize)
     }

src/stack.rs

@@ -5,10 +5,10 @@
 
 /// A trait for objects that hold ownership of a stack.
 pub trait Stack {
-  /// Returns the top of the stack.
+  /// Returns the base of the stack.
   /// On all modern architectures, the stack grows downwards,
   /// so this is the highest address.
-  fn top(&self) -> *mut u8;
+  fn base(&self) -> *mut u8;
   /// Returns the bottom of the stack.
   /// On all modern architectures, the stack grows downwards,
   /// so this is the lowest address.

tests/stack.rs

@@ -9,12 +9,12 @@ use fringe::{Stack, OsStack};
 fn default_stack() {
   let stack = OsStack::new(0).unwrap();
   // Make sure the topmost page of the stack, at least, is accessible.
-  unsafe { *(stack.top().offset(-1)) = 0; }
+  unsafe { *(stack.base().offset(-1)) = 0; }
 }
 
 #[test]
 fn one_page_stack() {
   let stack = OsStack::new(4096).unwrap();
   // Make sure the topmost page of the stack, at least, is accessible.
-  unsafe { *(stack.top().offset(-1)) = 0; }
+  unsafe { *(stack.base().offset(-1)) = 0; }
 }