diff --git a/lib/std/RingBuffer.zig b/lib/std/RingBuffer.zig deleted file mode 100644 index 5bdfb3e070..0000000000 --- a/lib/std/RingBuffer.zig +++ /dev/null @@ -1,230 +0,0 @@ -//! This ring buffer stores read and write indices while being able to utilise -//! the full backing slice by incrementing the indices modulo twice the slice's -//! length and reducing indices modulo the slice's length on slice access. This -//! means that whether the ring buffer is full or empty can be distinguished by -//! looking at the difference between the read and write indices without adding -//! an extra boolean flag or having to reserve a slot in the buffer. -//! -//! This ring buffer has not been implemented with thread safety in mind, and -//! therefore should not be assumed to be suitable for use cases involving -//! separate reader and writer threads. - -const Allocator = @import("std").mem.Allocator; -const assert = @import("std").debug.assert; -const copyForwards = @import("std").mem.copyForwards; - -const RingBuffer = @This(); - -data: []u8, -read_index: usize, -write_index: usize, - -pub const Error = error{ Full, ReadLengthInvalid }; - -/// Allocate a new `RingBuffer`; `deinit()` should be called to free the buffer. -pub fn init(allocator: Allocator, capacity: usize) Allocator.Error!RingBuffer { - const bytes = try allocator.alloc(u8, capacity); - return RingBuffer{ - .data = bytes, - .write_index = 0, - .read_index = 0, - }; -} - -/// Free the data backing a `RingBuffer`; must be passed the same `Allocator` as -/// `init()`. -pub fn deinit(self: *RingBuffer, allocator: Allocator) void { - allocator.free(self.data); - self.* = undefined; -} - -/// Returns `index` modulo the length of the backing slice. -pub fn mask(self: RingBuffer, index: usize) usize { - return index % self.data.len; -} - -/// Returns `index` modulo twice the length of the backing slice. -pub fn mask2(self: RingBuffer, index: usize) usize { - return index % (2 * self.data.len); -} - -/// Write `byte` into the ring buffer. Returns `error.Full` if the ring -/// buffer is full. -pub fn write(self: *RingBuffer, byte: u8) Error!void { - if (self.isFull()) return error.Full; - self.writeAssumeCapacity(byte); -} - -/// Write `byte` into the ring buffer. If the ring buffer is full, the -/// oldest byte is overwritten. -pub fn writeAssumeCapacity(self: *RingBuffer, byte: u8) void { - self.data[self.mask(self.write_index)] = byte; - self.write_index = self.mask2(self.write_index + 1); -} - -/// Write `bytes` into the ring buffer. Returns `error.Full` if the ring -/// buffer does not have enough space, without writing any data. -/// Uses memcpy and so `bytes` must not overlap ring buffer data. -pub fn writeSlice(self: *RingBuffer, bytes: []const u8) Error!void { - if (self.len() + bytes.len > self.data.len) return error.Full; - self.writeSliceAssumeCapacity(bytes); -} - -/// Write `bytes` into the ring buffer. If there is not enough space, older -/// bytes will be overwritten. -/// Uses memcpy and so `bytes` must not overlap ring buffer data. -pub fn writeSliceAssumeCapacity(self: *RingBuffer, bytes: []const u8) void { - assert(bytes.len <= self.data.len); - const data_start = self.mask(self.write_index); - const part1_data_end = @min(data_start + bytes.len, self.data.len); - const part1_len = part1_data_end - data_start; - @memcpy(self.data[data_start..part1_data_end], bytes[0..part1_len]); - - const remaining = bytes.len - part1_len; - const to_write = @min(remaining, remaining % self.data.len + self.data.len); - const part2_bytes_start = bytes.len - to_write; - const part2_bytes_end = @min(part2_bytes_start + self.data.len, bytes.len); - const part2_len = part2_bytes_end - part2_bytes_start; - @memcpy(self.data[0..part2_len], bytes[part2_bytes_start..part2_bytes_end]); - if (part2_bytes_end != bytes.len) { - const part3_len = bytes.len - part2_bytes_end; - @memcpy(self.data[0..part3_len], bytes[part2_bytes_end..bytes.len]); - } - self.write_index = self.mask2(self.write_index + bytes.len); -} - -/// Write `bytes` into the ring buffer. Returns `error.Full` if the ring -/// buffer does not have enough space, without writing any data. -/// Uses copyForwards and can write slices from this RingBuffer into itself. -pub fn writeSliceForwards(self: *RingBuffer, bytes: []const u8) Error!void { - if (self.len() + bytes.len > self.data.len) return error.Full; - self.writeSliceForwardsAssumeCapacity(bytes); -} - -/// Write `bytes` into the ring buffer. If there is not enough space, older -/// bytes will be overwritten. -/// Uses copyForwards and can write slices from this RingBuffer into itself. -pub fn writeSliceForwardsAssumeCapacity(self: *RingBuffer, bytes: []const u8) void { - assert(bytes.len <= self.data.len); - const data_start = self.mask(self.write_index); - const part1_data_end = @min(data_start + bytes.len, self.data.len); - const part1_len = part1_data_end - data_start; - copyForwards(u8, self.data[data_start..], bytes[0..part1_len]); - - const remaining = bytes.len - part1_len; - const to_write = @min(remaining, remaining % self.data.len + self.data.len); - const part2_bytes_start = bytes.len - to_write; - const part2_bytes_end = @min(part2_bytes_start + self.data.len, bytes.len); - copyForwards(u8, self.data[0..], bytes[part2_bytes_start..part2_bytes_end]); - if (part2_bytes_end != bytes.len) - copyForwards(u8, self.data[0..], bytes[part2_bytes_end..bytes.len]); - self.write_index = self.mask2(self.write_index + bytes.len); -} - -/// Consume a byte from the ring buffer and return it. Returns `null` if the -/// ring buffer is empty. -pub fn read(self: *RingBuffer) ?u8 { - if (self.isEmpty()) return null; - return self.readAssumeLength(); -} - -/// Consume a byte from the ring buffer and return it; asserts that the buffer -/// is not empty. -pub fn readAssumeLength(self: *RingBuffer) u8 { - assert(!self.isEmpty()); - const byte = self.data[self.mask(self.read_index)]; - self.read_index = self.mask2(self.read_index + 1); - return byte; -} - -/// Reads first `length` bytes written to the ring buffer into `dest`; Returns -/// Error.ReadLengthInvalid if length greater than ring or dest length -/// Uses memcpy and so `dest` must not overlap ring buffer data. -pub fn readFirst(self: *RingBuffer, dest: []u8, length: usize) Error!void { - if (length > self.len() or length > dest.len) return error.ReadLengthInvalid; - self.readFirstAssumeLength(dest, length); -} - -/// Reads first `length` bytes written to the ring buffer into `dest`; -/// Asserts that length not greater than ring buffer or dest length -/// Uses memcpy and so `dest` must not overlap ring buffer data. -pub fn readFirstAssumeLength(self: *RingBuffer, dest: []u8, length: usize) void { - assert(length <= self.len() and length <= dest.len); - const slice = self.sliceAt(self.read_index, length); - slice.copyTo(dest); - self.read_index = self.mask2(self.read_index + length); -} - -/// Reads last `length` bytes written to the ring buffer into `dest`; Returns -/// Error.ReadLengthInvalid if length greater than ring or dest length -/// Uses memcpy and so `dest` must not overlap ring buffer data. -/// Reduces write index by `length`. -pub fn readLast(self: *RingBuffer, dest: []u8, length: usize) Error!void { - if (length > self.len() or length > dest.len) return error.ReadLengthInvalid; - self.readLastAssumeLength(dest, length); -} - -/// Reads last `length` bytes written to the ring buffer into `dest`; -/// Asserts that length not greater than ring buffer or dest length -/// Uses memcpy and so `dest` must not overlap ring buffer data. -/// Reduces write index by `length`. -pub fn readLastAssumeLength(self: *RingBuffer, dest: []u8, length: usize) void { - assert(length <= self.len() and length <= dest.len); - const slice = self.sliceLast(length); - slice.copyTo(dest); - self.write_index = if (self.write_index >= self.data.len) - self.write_index - length - else - self.mask(self.write_index + self.data.len - length); -} - -/// Returns `true` if the ring buffer is empty and `false` otherwise. -pub fn isEmpty(self: RingBuffer) bool { - return self.write_index == self.read_index; -} - -/// Returns `true` if the ring buffer is full and `false` otherwise. -pub fn isFull(self: RingBuffer) bool { - return self.mask2(self.write_index + self.data.len) == self.read_index; -} - -/// Returns the length of data available for reading -pub fn len(self: RingBuffer) usize { - const wrap_offset = 2 * self.data.len * @intFromBool(self.write_index < self.read_index); - const adjusted_write_index = self.write_index + wrap_offset; - return adjusted_write_index - self.read_index; -} - -/// A `Slice` represents a region of a ring buffer. The region is split into two -/// sections as the ring buffer data will not be contiguous if the desired -/// region wraps to the start of the backing slice. -pub const Slice = struct { - first: []u8, - second: []u8, - - /// Copy data from `self` into `dest` - pub fn copyTo(self: Slice, dest: []u8) void { - @memcpy(dest[0..self.first.len], self.first); - @memcpy(dest[self.first.len..][0..self.second.len], self.second); - } -}; - -/// Returns a `Slice` for the region of the ring buffer starting at -/// `self.mask(start_unmasked)` with the specified length. -pub fn sliceAt(self: RingBuffer, start_unmasked: usize, length: usize) Slice { - assert(length <= self.data.len); - const slice1_start = self.mask(start_unmasked); - const slice1_end = @min(self.data.len, slice1_start + length); - const slice1 = self.data[slice1_start..slice1_end]; - const slice2 = self.data[0 .. length - slice1.len]; - return Slice{ - .first = slice1, - .second = slice2, - }; -} - -/// Returns a `Slice` for the last `length` bytes written to the ring buffer. -/// Does not check that any bytes have been written into the region. -pub fn sliceLast(self: RingBuffer, length: usize) Slice { - return self.sliceAt(self.write_index + self.data.len - length, length); -} diff --git a/lib/std/std.zig b/lib/std/std.zig index 891c0bc256..aaae4c2eba 100644 --- a/lib/std/std.zig +++ b/lib/std/std.zig @@ -29,7 +29,6 @@ pub const PriorityQueue = @import("priority_queue.zig").PriorityQueue; pub const PriorityDequeue = @import("priority_dequeue.zig").PriorityDequeue; pub const Progress = @import("Progress.zig"); pub const Random = @import("Random.zig"); -pub const RingBuffer = @import("RingBuffer.zig"); pub const SegmentedList = @import("segmented_list.zig").SegmentedList; pub const SemanticVersion = @import("SemanticVersion.zig"); pub const SinglyLinkedList = @import("SinglyLinkedList.zig");