Zig 0.17.0-dev (Split by item)

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seed

Isaac64.seed

fn seed(self: *Isaac64, init_s: u64, comptime rounds: usize) void

File

lib/std/Random/Isaac64.zig:86

Code

fn seed(self: *Isaac64, init_s: u64, comptime rounds: usize) void {
    // We ignore the multi-pass requirement since we don't currently expose full access to
    // seeding the self.m array completely.
    @memset(self.m[0..], 0);
    self.m[0] = init_s;

    // prescrambled golden ratio constants
    var a = [_]u64{
        0x647c4677a2884b7c,
        0xb9f8b322c73ac862,
        0x8c0ea5053d4712a0,
        0xb29b2e824a595524,
        0x82f053db8355e0ce,
        0x48fe4a0fa5a09315,
        0xae985bf2cbfc89ed,
        0x98f5704f6c44c0ab,
    };

    comptime var i: usize = 0;
    inline while (i < rounds) : (i += 1) {
        var j: usize = 0;
        while (j < self.m.len) : (j += 8) {
            comptime var x1: usize = 0;
            inline while (x1 < 8) : (x1 += 1) {
                a[x1] +%= self.m[j + x1];
            }

            a[0] -%= a[4];
            a[5] ^= a[7] >> 9;
            a[7] +%= a[0];
            a[1] -%= a[5];
            a[6] ^= a[0] << 9;
            a[0] +%= a[1];
            a[2] -%= a[6];
            a[7] ^= a[1] >> 23;
            a[1] +%= a[2];
            a[3] -%= a[7];
            a[0] ^= a[2] << 15;
            a[2] +%= a[3];
            a[4] -%= a[0];
            a[1] ^= a[3] >> 14;
            a[3] +%= a[4];
            a[5] -%= a[1];
            a[2] ^= a[4] << 20;
            a[4] +%= a[5];
            a[6] -%= a[2];
            a[3] ^= a[5] >> 17;
            a[5] +%= a[6];
            a[7] -%= a[3];
            a[4] ^= a[6] << 14;
            a[6] +%= a[7];

            comptime var x2: usize = 0;
            inline while (x2 < 8) : (x2 += 1) {
                self.m[j + x2] = a[x2];
            }
        }
    }

    @memset(self.r[0..], 0);
    self.a = 0;
    self.b = 0;
    self.c = 0;
    self.i = self.r.len; // trigger refill on first value
}