wip: std.mem.allocator

build.zig

@@ -15,18 +15,17 @@ pub fn build(b: *Builder) void {
     kernel.addAssemblyFile("src/arch/x86/switch_tasks.s");
 
     kernel.setBuildMode(b.standardReleaseOptions());
-    kernel.setTheTarget(builtin.Target{
+    kernel.setTheTarget(std.Target{
         .Cross = std.Target.Cross{
-            .arch = builtin.Target.Arch.i386,
-            .os = builtin.Target.Os.freestanding,
-            .abi = builtin.Target.Abi.none,
-            .cpu_features = builtin.Target.CpuFeatures.initFromCpu(
+            .arch = std.Target.Arch.i386,
+            .os = std.Target.Os.freestanding,
+            .abi = std.Target.Abi.none,
+            .cpu_features = std.Target.CpuFeatures.initFromCpu(
                 builtin.Arch.i386,
                 &builtin.Target.x86.cpu._i686,
             ),
         },
     });
-
     kernel.setLinkerScriptPath("src/arch/x86/linker.ld");
     b.default_step.dependOn(&kernel.step);
 }

qemu.sh

@@ -1,19 +1,21 @@
 #!/bin/bash
+# usage: ./qemu.sh start
+#        ./qemu.sh quit
 
 QEMU_SOCKET=/tmp/qemu.sock
 QEMU_MONITOR="sudo socat - UNIX-CONNECT:${QEMU_SOCKET}"
 QEMU_GDB_PORT=4242
 KERNEL=build/kernel
 
-start() {
+qemu_start() {
 	touch disk.img
 	# sudo pkill -9 qemu-system-i386
 	sudo qemu-system-i386 \
 		-gdb tcp::${QEMU_GDB_PORT} \
 		-monitor unix:${QEMU_SOCKET},server,nowait \
 		-enable-kvm \
-		-m 1341M \
 		-curses \
+		-m 1341M \
 		-hda disk.img \
 		-kernel ${KERNEL}
 		# -drive file=disk.img,if=virtio\
@@ -27,16 +29,7 @@ start() {
 		# -serial mon:stdio \
 }
 
-monitor() { sudo ${QEMU_MONITOR}; }
-monitor-exec() { echo "$1" | sudo ${QEMU_MONITOR} >/dev/null; }
+qemu_quit() { echo quit | sudo ${QEMU_MONITOR} >/dev/null; }
+qemu_monitor() { sudo ${QEMU_MONITOR}; }
 
-quit() { monitor-exec quit; }
-
-reload() {
-	monitor-exec stop
-	# monitor "change ide1-cd0 ${KERNEL}"
-	monitor-exec system_reset
-	monitor-exec cont
-}
-
-"$@"
+qemu_"$@"

src/console.zig

@@ -67,7 +67,7 @@ pub fn keyboard_callback(char: u8) void {
 }
 
 pub fn loop() void {
-    input_ring.init() catch unreachable;
+    input_ring.init(vmem.allocator) catch unreachable;
     input_ring.task = task.current_task;
     ps2.keyboard_callback = keyboard_callback;
     print("> ", .{});

src/driver/ide.zig

@@ -91,8 +91,9 @@ const IDEDevice = struct {
         var err: u8 = 0;
         var status: u8 = 0;
 
-        var self = try kernel.vmem.create(IDEDevice);
-        errdefer kernel.vmem.destroy(self);
+        // TODO: make this nicer
+        var self = try kernel.vmem.allocator.create(IDEDevice);
+        errdefer kernel.vmem.allocator.destroy(self);
         self.reserved = 1;
         self.channel = channel;
         self.drive = drive;

src/main.zig

@@ -30,7 +30,7 @@ export fn kmain(magic: u32, info: *const multiboot.MultibootInfo) noreturn {
     _ = task.new(@ptrToInt(topbar)) catch unreachable;
     _ = task.new(@ptrToInt(console.loop)) catch unreachable;
 
-    var buf = vmem.create([512]u8) catch unreachable;
+    var buf = vmem.allocator.create([512]u8) catch unreachable;
     println("buf at 0x{x}", .{@ptrToInt(buf)});
     driver.ide.first_ide_drive.read(2, buf);
 

src/ring_buffer.zig

@@ -3,16 +3,17 @@ usingnamespace @import("index.zig");
 pub fn Ring(comptime T: type) type {
     return struct {
         const Self = @This();
-        const Size = u10; // 0-1024
+        const Size = u10; // 0-1023
         const size = @import("std").math.maxInt(Size);
+        allocator: std.mem.Allocator = undefined,
         buffer: *[size]T,
         task: ?*task.TaskNode = null,
         read_index: Size = 0,
         write_index: Size = 0,
 
-        //TODO: allocator argument and remove the namespace
-        pub fn init(ring: *Self) !void {
-            ring.buffer = try vmem.create(@TypeOf(ring.buffer.*));
+        pub fn init(ring: *Self, alloc: std.mem.Allocator) !void {
+            ring.allocator = alloc;
+            ring.buffer = try ring.allocator.create(@TypeOf(ring.buffer.*));
         }
 
         pub fn write(ring: *Self, elem: T) void {
@@ -24,7 +25,7 @@ pub fn Ring(comptime T: type) type {
         pub fn read(ring: *Self) ?T {
             if (ring.write_index == ring.read_index) return null;
             const id = ring.read_index;
-            ring.read_index +%= 1;
+            ring.read_index +%= 1; // add with overflow to loop the ring
             return ring.buffer[id];
         }
     };

src/task.zig

@@ -34,6 +34,7 @@ pub const TaskState = enum {
 };
 
 pub const Task = struct {
+    stack: *[STACK_SIZE]u8 = undefined,
     esp: usize,
     tid: u16,
     time_used: u64 = 0,
@@ -44,8 +45,8 @@ pub const Task = struct {
 
     pub fn create(entrypoint: usize) !*Task {
         // Allocate and initialize the thread structure.
-        var t = try vmem.create(Task);
-        errdefer vmem.destroy(t);
+        var t = try vmem.allocator.create(Task);
+        errdefer vmem.allocator.destroy(t);
 
         t.time_used = 0;
         t.state = .ReadyToRun;
@@ -54,7 +55,8 @@ pub const Task = struct {
         assert(tid_counter != 0); //overflow
 
         // allocate a new stack
-        t.esp = (try vmem.malloc(STACK_SIZE)) + STACK_SIZE;
+        t.stack = try vmem.allocator.create([STACK_SIZE]u8);
+        t.esp = @ptrToInt(t.stack) + STACK_SIZE;
         // if the tasks rets from its main function, it will go to terminate
         // NOTE: if terminate is called this way it has an incorrect ebp!
         t.esp -= 4;
@@ -70,8 +72,8 @@ pub const Task = struct {
     }
 
     pub fn destroy(self: *Task) void {
-        vmem.free(self.esp);
-        vmem.destroy(self);
+        vmem.allocator.destroy(self.stack);
+        vmem.allocator.destroy(self);
     }
 };
 
@@ -82,8 +84,8 @@ pub fn new(entrypoint: usize) !*TaskNode {
     task.lock_scheduler();
     defer task.unlock_scheduler();
 
-    const node = try vmem.create(TaskNode);
-    errdefer vmem.destroy(node);
+    const node = try vmem.allocator.create(TaskNode);
+    errdefer vmem.allocator.destroy(node);
 
     node.data = try Task.create(entrypoint);
     ready_tasks.prepend(node);
@@ -99,7 +101,7 @@ pub fn wakeup_tick(tick: usize) bool {
     while (task.sleeping_tasks.popZero()) |sleepnode| {
         const tasknode = sleepnode.data;
         tasknode.data.state = .ReadyToRun;
-        vmem.free(@ptrToInt(sleepnode));
+        vmem.allocator.destroy(sleepnode);
         task.ready_tasks.prepend(tasknode);
         popped = true;
     }
@@ -111,7 +113,7 @@ pub fn usleep(usec: u64) !void {
     assert(current_task.data.state == .Running);
     update_time_used();
 
-    const node = try vmem.create(SleepNode);
+    const node = try vmem.allocator.create(SleepNode);
 
     lock_scheduler();
     defer unlock_scheduler();
@@ -177,7 +179,7 @@ pub fn cleaner_loop() noreturn {
         if (terminated_tasks.popFirst()) |n| {
             notify("DESTROYING {}", .{n.data.tid});
             n.data.destroy();
-            vmem.destroy(n);
+            vmem.allocator.destroy(n);
         } else {
             notify("NOTHING TO CLEAN", .{});
             block(.Paused);

src/vga.zig

@@ -10,7 +10,7 @@ pub var vga = VGA{
     .vram = @intToPtr([*]VGAEntry, 0xb8000)[0..0x4000],
     .cursor = 80 * 2,
     .foreground = Color.Black,
-    .background = Color.LightGrey,
+    .background = Color.White,
 };
 
 // Color codes.
@@ -68,8 +68,8 @@ pub fn topbar() void {
     // println("topbar1");
     while (true) {
         const cursor = vga.cursor;
-        vga.background = Color.Green;
-        vga.foreground = Color.LightGrey;
+        vga.background = Color.Black;
+        vga.foreground = Color.White;
         vga.cursor = 0;
         vga.cursor_enabled = false;
 

src/vmem.zig

@@ -1,5 +1,5 @@
 pub usingnamespace @import("index.zig");
-pub const allocator: std.mem.Allocator = undefined;
+pub var allocator: std.mem.Allocator = undefined;
 
 // TODO: make a better memory allocator
 // stupid simple virtual memory allocator
@@ -8,44 +8,78 @@ pub const allocator: std.mem.Allocator = undefined;
 //  - no allocation bigger than a page
 
 const stack_size: usize = (layout.HEAP_END - layout.HEAP) / x86.PAGE_SIZE;
-var stack: [stack_size]usize = undefined; // Stack of free virtual addresses
 var stack_index: usize = 0; // Index into the stack.
+var stack: [stack_size]usize = undefined; // Stack of free virtual addresses
 
 pub fn available() usize {
     return stack_index * x86.PAGE_SIZE;
 }
 
-pub fn malloc(size: usize) !usize {
-    if (available() == 0) {
-        return error.OutOfMemory;
+fn dealloc(addr: usize) void {
+    x86.paging.unmap(addr);
+    stack[stack_index] = addr;
+    stack_index += 1;
 }
+
+const Error = error{OutOfMemory};
+
+fn realloc(
+    self: *std.mem.Allocator,
+    old_mem: []u8,
+    old_alignment: u29,
+    new_byte_count: usize,
+    new_alignment: u29,
+) ![]u8 {
+    if (old_mem.len == 0) {
+        // new allocation
+        assert(new_byte_count < x86.PAGE_SIZE); // this allocator only support 1:1 mapping
+        if (available() == 0) return error.OutOfMemory;
         stack_index -= 1;
         var vaddr: usize = stack[stack_index];
         try x86.paging.mmap(vaddr, null);
-    return vaddr;
+        return @intToPtr([*]u8, vaddr)[0..new_byte_count];
+    }
+    // free
+    if (new_byte_count == 0) {
+        dealloc(@ptrToInt(&old_mem[0]));
+        return &[_]u8{};
+    }
+    println("vmem: unsupported allocator operation", .{});
+    x86.hang();
+    // return undefined;
 }
 
-pub fn create(comptime T: type) !*T {
-    assert(@sizeOf(T) < x86.PAGE_SIZE); // this allocator only support 1:1 mapping
-    return @intToPtr(*T, try malloc(@sizeOf(T)));
+fn shrink(
+    self: *std.mem.Allocator,
+    old_mem: []u8,
+    old_alignment: u29,
+    new_byte_count: usize,
+    new_alignment: u29,
+) []u8 {
+    // free
+    if (new_byte_count == 0) {
+        dealloc(@ptrToInt(&old_mem[0]));
+        return &[_]u8{};
     }
 
-pub fn destroy(O: var) void {
-    vmem.free(@ptrToInt(O));
-}
-
-pub fn free(address: usize) void {
-    x86.paging.unmap(address);
-    stack[stack_index] = address;
-    stack_index += 1;
+    println("vmem doesn't support shrinking, {}, {}, {}, {}", .{
+        old_mem,
+        old_alignment,
+        new_byte_count,
+        new_alignment,
+    });
+    x86.hang();
+    // return undefined;
 }
 
 pub fn init() void {
+    allocator = std.mem.Allocator{
+        .reallocFn = realloc,
+        .shrinkFn = shrink,
+    };
     var addr: usize = layout.HEAP;
     while (addr < layout.HEAP_END) : (addr += x86.PAGE_SIZE) {
-        // println("addr {x}", addr);
         stack[stack_index] = addr;
         stack_index += 1;
-        // return;
     }
 }