70 lines
2.0 KiB
Zig
70 lines
2.0 KiB
Zig
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const std = @import("std");
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pub fn RingBuffer(comptime T: type) type {
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return struct {
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const Self = @This();
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const Index = usize;
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const Atomic = std.atomic.Atomic;
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const max_capacity = (@as(Index, 1) << @typeInfo(Index).Int.bits - 1) - 1; // half the range of index type
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const log = std.log.scoped(.RingBuffer);
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read: Atomic(Index),
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write: Atomic(Index),
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buf: []T,
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const Error = error{buffer_full};
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pub fn init(buf: []T) Self {
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std.debug.assert(std.math.isPowerOfTwo(buf.len)); // capacity must be a power of two
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std.debug.assert(buf.len <= max_capacity);
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return .{
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.read = Atomic(Index).init(0),
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.write = Atomic(Index).init(0),
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.buf = buf,
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};
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}
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pub fn push(self: *Self, value: T) Error!void {
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const read_idx = self.read.load(.Acquire);
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const write_idx = self.write.load(.Acquire);
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// Check to see if Queue is full
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if (write_idx - read_idx == self.buf.len) return Error.buffer_full;
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self.buf[self.mask(write_idx)] = value;
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std.atomic.fence(.Release);
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self.write.store(write_idx + 1, .Release);
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}
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pub fn pop(self: *Self) ?T {
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const read_idx = self.read.load(.Acquire);
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const write_idx = self.write.load(.Acquire);
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if (read_idx == write_idx) return null;
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std.atomic.fence(.Acquire);
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const value = self.buf[self.mask(self.read)];
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std.atomic.fence(.Release);
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self.read.store(read_idx + 1, .Release);
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return value;
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}
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pub fn len(self: *const Self) Index {
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const read_idx = self.read.load(.Acquire);
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const write_idx = self.write.load(.Acquire);
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return write_idx - read_idx;
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}
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fn mask(self: *const Self, idx: Index) Index {
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return idx & (self.buf.len - 1);
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}
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};
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}
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