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bhb/struct_repro.zig

Last active March 24, 2023 23:06
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  1. bhb revised this gist Mar 24, 2023. No changes.
  2. bhb created this gist Mar 24, 2023.
    107 changes: 107 additions & 0 deletions struct_repro.zig
    View file
    Original file line number Diff line number Diff line change
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    const std = @import("std");

    // zig version: 0.11.0-dev.2249+dcdb87836

    /////////////////////////////////////////////
    // zig run -O Debug struct_repro.zig

    // rand 1 0.47344332933425903
    // rand 1 0.3766399025917053
    // rand 2 0.6770572662353516
    // rand 2 0.5922629833221436
    // rand 3 0.8293377757072449
    // rand 3 0.5863988399505615
    // rand 4 0.6468727588653564
    // rand 4 0.18700581789016724
    // [1] 67389 abort zig run -O Debug struct_repro.zig

    ///////////////////////////////////////////////

    // zig run -O ReleaseSafe struct_repro.zig

    // rand 1 0.6165003180503845
    // rand 1 0.09705868363380432
    // rand 2 0.2942855656147003
    // rand 2 0.3366544246673584
    // rand 3 0.0039062497671693563
    // rand 3 0.00000000118555465444814
    // rand 4 0.900171160697937
    // rand 4 0.3476182520389557
    // rand 5 0.978439450263977
    // rand 5 0.04816720262169838

    ///////////////////////////////////////////////

    // zig run -O ReleaseFast struct_repro.zig

    // rand 1 0.07979004830121994
    // rand 1 0.5140153765678406
    // rand 2 0.5294123888015747
    // rand 2 0.6598545908927917
    // rand 3 0
    // rand 3 0
    // rand 4 0
    // rand 4 0
    // rand 5 0
    // rand 5 0

    const RNG = struct {
    rand: std.rand.Random,

    pub fn init() !RNG {
    var prng = std.rand.DefaultPrng.init(blk: {
    var seed: u64 = undefined;
    try std.os.getrandom(std.mem.asBytes(&seed));
    break :blk seed;
    });
    const rand = prng.random();

    return RNG{ .rand = rand };
    }

    pub fn next(self: *RNG) f32 {
    return self.rand.float(f32);
    }
    };

    fn rand_double1(rand: std.rand.Random) f32 {
    return rand.float(f32);
    }

    fn rand_double2(rng: *RNG) f32 {
    return rng.rand.float(f32);
    }

    fn rand_double3(rng: *RNG) f32 {
    return rng.next() * 2;
    }

    pub fn main() !void {
    var prng = std.rand.DefaultPrng.init(blk: {
    var seed: u64 = undefined;
    try std.os.getrandom(std.mem.asBytes(&seed));
    break :blk seed;
    });
    const rand = prng.random();

    // calling float directly works
    std.debug.print("rand 1 {d} \n", .{rand.float(f32)});
    std.debug.print("rand 1 {d} \n", .{rand.float(f32)});

    // passing rand to function works
    std.debug.print("rand 2 {d} \n", .{rand_double1(rand)});
    std.debug.print("rand 2 {d} \n", .{rand_double1(rand)});

    // pass the rng wrapper to a function
    var rng = try RNG.init();
    std.debug.print("rand 3 {d} \n", .{rand_double2(&rng)});
    std.debug.print("rand 3 {d} \n", .{rand_double2(&rng)});

    // use next fn
    std.debug.print("rand 4 {d} \n", .{rng.next()});
    std.debug.print("rand 4 {d} \n", .{rng.next()});

    // pass to rng to function
    std.debug.print("rand 5 {d} \n", .{rand_double3(&rng)});
    std.debug.print("rand 5 {d} \n", .{rand_double3(&rng)});
    }