tiny.reticulum.wire.flags

1const std = @import("std");23pub const HeaderType = enum(u1) {4    one = 0,5    two = 1,6};78pub const TransportType = enum(u1) {9    broadcast = 0,10    transport = 1,11};1213pub const DestinationType = enum(u2) {14    single = 0,15    group = 1,16    plain = 2,17    link = 3,18};1920pub const PacketType = enum(u2) {21    data = 0,22    announce = 1,23    link_request = 2,24    proof = 3,25};2627pub const Flags = struct {28    ifac: u1,29    header: HeaderType,30    context: u1,31    transport: TransportType,32    destination: DestinationType,33    packet: PacketType,3435    /// Packs the six flag fields into the byte that leads a packet header: the36    /// access-code flag at bit 7, the header shape at bit 6, the context flag37    /// at bit 5, whether the packet is carried for another node at bit 4, the38    /// destination type at bits 3 and 2, and the packet type at bits 1 and 0,39    /// for a caller building that header, following Reticulum@1.5.040    /// RNS/Packet.py:172-174.41    pub fn encode(self: Flags) u8 {42        return (@as(u8, self.ifac) << 7) |43            (@as(u8, @backingInt(self.header)) << 6) |44            (@as(u8, self.context) << 5) |45            (@as(u8, @backingInt(self.transport)) << 4) |46            (@as(u8, @backingInt(self.destination)) << 2) |47            @as(u8, @backingInt(self.packet));48    }4950    /// Reads the six flag fields back out of the first byte of an arriving51    /// packet, at the bit positions the packing uses, following Reticulum@1.5.052    /// RNS/Packet.py:251-255. Every bit pattern names a value in its field, so53    /// any byte decodes and encodes back to itself.54    pub fn decode(byte: u8) Flags {55        return .{56            .ifac = @truncate(byte >> 7),57            .header = @fromBackingInt(@intCast(@as(u1, @truncate(byte >> 6)))),58            .context = @truncate(byte >> 5),59            .transport = @fromBackingInt(@intCast(@as(u1, @truncate(byte >> 4)))),60            .destination = @fromBackingInt(@intCast(@as(u2, @truncate(byte >> 2)))),61            .packet = @fromBackingInt(@intCast(@as(u2, @truncate(byte)))),62        };63    }64};6566test "Reticulum@1.5.0 RNS/Packet.py:172-174 packs each header type" {67    const base = Flags{68        .ifac = 0,69        .header = .one,70        .context = 0,71        .transport = .broadcast,72        .destination = .single,73        .packet = .data,74    };75    try std.testing.expectEqual(@as(u8, 0x00), base.encode());76    var header_two = base;77    header_two.header = .two;78    try std.testing.expectEqual(@as(u8, 0x40), header_two.encode());79}8081test "Reticulum@1.5.0 RNS/Packet.py:172-174 packs each destination type" {82    var value = Flags{83        .ifac = 0,84        .header = .one,85        .context = 0,86        .transport = .broadcast,87        .destination = .single,88        .packet = .data,89    };90    for ([_]u8{ 0x00, 0x04, 0x08, 0x0c }, 0..) |expected, raw| {91        value.destination = @fromBackingInt(@intCast(@as(u2, @intCast(raw))));92        try std.testing.expectEqual(expected, value.encode());93    }94}9596test "Reticulum@1.5.0 RNS/Packet.py:60-63,172 packs each packet type" {97    var value = Flags{98        .ifac = 0,99        .header = .one,100        .context = 0,101        .transport = .broadcast,102        .destination = .single,103        .packet = .data,104    };105    for ([_]u8{ 0x00, 0x01, 0x02, 0x03 }, 0..) |expected, raw| {106        value.packet = @fromBackingInt(@intCast(@as(u2, @intCast(raw))));107        try std.testing.expectEqual(expected, value.encode());108    }109}110111test "Reticulum@1.5.0 RNS/Packet.py:251-255 preserves every flag bit" {112    const decoded = Flags.decode(0xff);113    try std.testing.expectEqual(@as(u1, 1), decoded.ifac);114    try std.testing.expectEqual(HeaderType.two, decoded.header);115    try std.testing.expectEqual(@as(u1, 1), decoded.context);116    try std.testing.expectEqual(TransportType.transport, decoded.transport);117    try std.testing.expectEqual(DestinationType.link, decoded.destination);118    try std.testing.expectEqual(PacketType.proof, decoded.packet);119    try std.testing.expectEqual(@as(u8, 0xff), decoded.encode());120}

1pub const flags = @import("flags.zig");