first

.forgejo/workflows/test.yaml

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+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    runs-on: nixos
+    env:
+      ZIG_LOCAL_CACHE_DIR: /zig/local-cache
+      ZIG_GLOBAL_CACHE_DIR: /zig/global-cache
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Update
+        run: nix flake update
+      - name: Test
+        run: nix develop .#default -c zig build test
+        

.gitignore

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+/.zig-cache
+/zig-out
+

LICENSE

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+MIT License
+
+Copyright © 2004 Jeffrey C. Ollie
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# circular buffer
+
+Simple circular buffer for Zig. Buffers must be sized in increments of powers of
+two to simplify (and hopefully speed up) the math.

build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    _ = b.addModule("circular-buffer", .{
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const mod_tests = b.addTest(.{
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_mod_tests = b.addRunArtifact(mod_tests);
+
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_mod_tests.step);
+}

build.zig.zon

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+.{
+    .name = "circular-buffer",
+    .version = "0.1.0",
+
+    .minimum_zig_version = "0.13.0",
+
+    .dependencies = .{},
+
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        "LICENSE",
+        "README.md",
+    },
+}

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1725634671,
+        "narHash": "sha256-v3rIhsJBOMLR8e/RNWxr828tB+WywYIoajrZKFM+0Gg=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "574d1eac1c200690e27b8eb4e24887f8df7ac27c",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-unstable",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  inputs = {
+    nixpkgs = {
+      url = "nixpkgs/nixos-unstable";
+    };
+    flake-utils = {
+      url = "github:numtide/flake-utils";
+    };
+  };
+
+  outputs = {
+    nixpkgs,
+    flake-utils,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in {
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = [
+            pkgs.zig_0_13
+          ];
+          shellHook = ''
+            export name=osc-fuzzer
+          '';
+        };
+      }
+    );
+}

src/root.zig

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+const std = @import("std");
+
+pub fn CircularBuffer(comptime T: type) type {
+    const info = @typeInfo(T);
+    std.debug.assert(info == .Int);
+    std.debug.assert(info.Int.signedness == .unsigned);
+
+    return struct {
+        data: [std.math.maxInt(T) + 1]u8 = undefined,
+        head: T = 0,
+        tail: T = 0,
+        full: bool = false,
+
+        pub fn isEmpty(self: *CircularBuffer(T)) bool {
+            return self.head == self.tail and !self.full;
+        }
+
+        pub fn isFull(self: *CircularBuffer(T)) bool {
+            return self.full;
+        }
+
+        pub fn reset(self: *CircularBuffer(T)) void {
+            self.head = 0;
+            self.tail = 0;
+            self.full = false;
+        }
+
+        pub fn size(self: *CircularBuffer(size)) T {
+            if (self.full) return std.math.maxInt(T);
+            if (self.head >= self.tail) return @intCast(self.head - self.tail);
+            return @intCast(std.math.maxInt(T) + self.head - self.tail);
+        }
+
+        fn advance(self: *CircularBuffer(T)) void {
+            self.head +%= 1;
+            if (self.full) self.tail +%= 1;
+            self.full = self.head == self.tail;
+        }
+
+        fn retreat(self: *CircularBuffer(T)) void {
+            self.full = false;
+            self.tail -%= 1;
+        }
+
+        pub fn pushByte(self: *CircularBuffer(T), byte: u8) void {
+            self.data[self.head] = byte;
+            self.advance();
+        }
+
+        pub fn popByte(self: *CircularBuffer(T)) !u8 {
+            if (self.isEmpty()) return error.BufferEmpty;
+            defer self.retreat();
+            return self.data[self.tail];
+        }
+
+        pub fn pushAll(self: *CircularBuffer(T), data: []const u8) void {
+            if (data.len >= self.data.len) {
+                @memcpy(&self.data, data[(data.len - self.data.len)..]);
+                self.tail = 0;
+                self.head = 0;
+                self.full = true;
+                return;
+            }
+
+            for (data) |c| self.pushByte(c);
+        }
+
+        pub fn write(self: *CircularBuffer(T), writer: anytype) !void {
+            if (self.head <= self.tail) {
+                try writer.writeAll(self.data[self.tail..]);
+                try writer.writeAll(self.data[0..self.head]);
+            } else {
+                try writer.writeAll(self.data[self.tail..self.head]);
+            }
+        }
+    };
+}
+
+test "circular buffer 1" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("a", result);
+}
+
+test "circular buffer 2" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    cb.pushByte('b');
+    cb.pushByte('c');
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(3, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("abc", result);
+}
+
+test "circular buffer 3" {
+    var cb = CircularBuffer(u2){};
+    cb.pushByte('a');
+    cb.pushByte('b');
+    cb.pushByte('c');
+    cb.pushByte('d');
+    cb.pushByte('e');
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(1, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('e', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+    try std.testing.expectEqual('d', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("bcde", result);
+}
+
+test "circular buffer 4" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("a");
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(1, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("a", result);
+}
+
+test "circular buffer 5" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("ab");
+    try std.testing.expect(!cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(2, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("ab", result);
+}
+
+test "circular buffer 6" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("abcd");
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(0, cb.head);
+    try std.testing.expectEqual('a', cb.data[0]);
+    try std.testing.expectEqual('b', cb.data[1]);
+    try std.testing.expectEqual('c', cb.data[2]);
+    try std.testing.expectEqual('d', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("abcd", result);
+}
+
+test "circular buffer 7" {
+    var cb = CircularBuffer(u2){};
+    cb.pushAll("abcde");
+    try std.testing.expect(cb.isFull());
+    try std.testing.expect(!cb.isEmpty());
+    try std.testing.expectEqual(0, cb.tail);
+    try std.testing.expectEqual(0, cb.head);
+    try std.testing.expectEqual('b', cb.data[0]);
+    try std.testing.expectEqual('c', cb.data[1]);
+    try std.testing.expectEqual('d', cb.data[2]);
+    try std.testing.expectEqual('e', cb.data[3]);
+
+    var tmp: [16]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&tmp);
+    try cb.write(fbs.writer());
+    const result = fbs.getWritten();
+    try std.testing.expectEqualStrings("bcde", result);
+}