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// zig 0.14.0-dev.1511+54b668f8a (2024-09-12) |
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// zig build-exe uuidv7.zig -O ReleaseSmall -femit-bin=uuidv7 |
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// Copyright 2024 (c) AJ ONeal |
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// Licensed under the MPL-2.0 |
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const std = @import("std"); |
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const builtin = @import("builtin"); |
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pub fn main() !void { |
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const stdout = std.io.getStdOut().writer(); |
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const getrandom = if (builtin.os.tag == .windows) std.os.windows.RtlGenRandom else std.posix.getrandom; |
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const uuid7 = try generateUUIDv7(getrandom); |
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const uuid7str = try uuidToString(uuid7); |
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try stdout.print("{s}\n", .{uuid7str}); |
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} |
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pub const UUID = struct { |
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time_high: u32, |
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time_low: u16, |
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version_random1: u16, |
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variant_random2: u16, |
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random3: u16, |
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random4: u32, |
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}; |
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fn generateUUIDv7(getrandom: anytype) !UUID { |
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// Get the current Unix timestamp in milliseconds |
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const inow = std.time.milliTimestamp(); |
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const now: u64 = @intCast(inow); // we use 48 bits |
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const time_low: u16 = @truncate(now); |
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const time_high: u32 = @truncate(now >> 16); |
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const version = (0b111 << 12); // 0b111 is the 7 in UUIDv7 |
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const version_mask = 0x0FFF; |
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const variant = (0b10 << 14); // 0b10 is the endianness-indicating variant |
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const variant_mask = 0b0011111111111111; |
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var random_bytes: [10]u8 = undefined; |
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try getrandom(&random_bytes); |
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const version_random1: u16 = (((@as(u16, random_bytes[0]) << 8) | @as(u16, random_bytes[1])) & |
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version_mask) | version; |
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const variant_random2: u16 = ((((@as(u16, random_bytes[2]) << 8) | @as(u16, random_bytes[3])) & |
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variant_mask)) | variant; |
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const random3: u16 = (@as(u16, random_bytes[4]) << 8) | @as(u16, random_bytes[5]); |
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const random4: u32 = (@as(u32, random_bytes[6]) << 24) | |
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(@as(u32, random_bytes[7]) << 16) | |
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(@as(u32, random_bytes[8]) << 8) | |
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@as(u32, random_bytes[9]); |
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return UUID{ |
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.time_high = time_high, |
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.time_low = time_low, |
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.version_random1 = version_random1, |
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.variant_random2 = variant_random2, |
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.random3 = random3, |
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.random4 = random4, |
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}; |
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} |
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fn uuidToString(uuid: UUID) ![]const u8 { |
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var buffer: [36]u8 = undefined; |
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// time_h32-t_16-verh-varh-rand03rand04 |
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// 019212d3-87f4-7d25-902e-b8d39fe07f08 |
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return std.fmt.bufPrint(&buffer, "{x:08}-{x}-{x}-{x:04}-{x:04}{x:08}", .{ uuid.time_high, uuid.time_low, uuid.version_random1, uuid.variant_random2, uuid.random3, uuid.random4 }); |
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} |
