From 4cbbb2053ff7820b3120d46774e6df4f242be215 Mon Sep 17 00:00:00 2001
From: Erin <erin@hashbang.sh>
Date: Mon, 18 Sep 2017 22:32:47 -0500
Subject: [PATCH] +lib/alloc/bump: shitty bump allocator for testing

---
 lib/alloc/bump/Cargo.lock |  4 +++
 lib/alloc/bump/Cargo.toml |  6 ++++
 lib/alloc/bump/src/lib.rs | 90 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)
 create mode 100644 lib/alloc/bump/Cargo.lock
 create mode 100644 lib/alloc/bump/Cargo.toml
 create mode 100644 lib/alloc/bump/src/lib.rs

diff --git a/lib/alloc/bump/Cargo.lock b/lib/alloc/bump/Cargo.lock
new file mode 100644
index 0000000..a5e95c7
--- /dev/null
+++ b/lib/alloc/bump/Cargo.lock
@@ -0,0 +1,4 @@
+[root]
+name = "sparkle_bump_alloc"
+version = "0.1.0"
+
diff --git a/lib/alloc/bump/Cargo.toml b/lib/alloc/bump/Cargo.toml
new file mode 100644
index 0000000..f7633b1
--- /dev/null
+++ b/lib/alloc/bump/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "sparkle_bump_alloc"
+version = "0.1.0"
+authors = ["Erin <erin@hashbang.sh>"]
+
+[dependencies]
diff --git a/lib/alloc/bump/src/lib.rs b/lib/alloc/bump/src/lib.rs
new file mode 100644
index 0000000..3359675
--- /dev/null
+++ b/lib/alloc/bump/src/lib.rs
@@ -0,0 +1,90 @@
+//! Bullshit naïve bump allocator for kernel heap testing
+//! Lovingly ripped off from^W^W^W inspired by phil-opp's rust os articles
+
+#![feature(const_fn)]
+#![no_std]
+
+
+#[derive(Debug)]
+pub struct Heap {
+    /// Start of the heap we're allocating into.
+    heap_start: usize,
+    /// End of the heap we're allocating into.
+    heap_end: usize,
+
+    /// The next free address in the heap. Absolute address, *not* relative to `heap_start`!
+    next_addr: usize,
+}
+
+impl Heap {
+    /// Create a new allocator using the given range
+    /// [heap_start, heap_start+heap_size] for the heap
+    pub const fn new(heap_start: usize, heap_size: usize) -> Heap {
+        Heap {
+            heap_start: heap_start,
+            heap_end: heap_start + heap_size,
+
+            next_addr: heap_start,
+        }
+    }
+
+    /// Allocate a chunk of memory with (size, alignment)
+    pub fn allocate(&mut self, size: usize, align: usize) -> Option<*mut u8> {
+        let alloc_start = align_up(self.next_addr, align);
+        let alloc_end = alloc_start.saturating_add(size);
+
+        if alloc_end <= self.heap_end {
+            self.next_addr = alloc_end;
+            Some(alloc_start as *mut u8)
+        } else {
+            None
+        }
+    }
+
+    pub fn deallocate(&mut self, _ptr: *mut u8, _size: usize, _align: usize) {
+        // nothing! just leak
+    }
+}
+
+// unsafe impl Alloc for BumpAllocator {
+//     #[inline]
+//     unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+//         self.allocate(layout.size(), layout.align()).ok_or(AllocErr::Exhausted {request: layout})
+//     }
+
+//     unsafe fn dealloc(&mut self, _ptr: *mut u8, _layout: Layout) {
+//         // just leak
+//     }
+
+//     fn oom(&mut self, err: AllocErr) -> ! {
+//         panic!("kheap OOM: {:?}!", err);
+//     }
+
+//     // Just copy the whole thing up to a new block
+//     unsafe fn realloc(&mut self, ptr: *mut u8, layout: Layout, new_layout: Layout) -> Result<*mut u8, AllocErr> {
+
+//         use core::{ptr, cmp};
+
+//         let copy_size = cmp::min(layout.size(), new_layout.size()); // copy len = min(size, size')
+//         let new_ptr = self.alloc(new_layout)?; // alloc new block
+//         ptr::copy(ptr, new_ptr, copy_size);
+//         self.dealloc(ptr, layout); // dealloc old pointer
+
+//         Ok(new_ptr)
+//     }
+// }
+
+pub fn align_down(addr: usize, align: usize) -> usize {
+    if align.is_power_of_two() {
+        // unset bits after alignment bit
+        addr & !(align - 1)
+    } else if align == 0 {
+        addr
+    } else {
+        panic!("`align` must be a power of 2");
+    }
+}
+
+pub fn align_up(addr: usize, align: usize) -> usize {
+    align_down(addr + align - 1, align)
+}