const math = @import("std").math;
pub fn bitReverse(comptime T: type, value: T, N: usize) T {
const r = @bitReverse(value);
return r >> @intCast(math.Log2Int(T), @typeInfo(T).Int.bits - N);
}
test "bitReverse" {
const std = @import("std");
const ReverseBitsTest = struct {
in: u16,
bit_count: u5,
out: u16,
};
var reverse_bits_tests = [_]ReverseBitsTest{
.{ .in = 1, .bit_count = 1, .out = 1 },
.{ .in = 1, .bit_count = 2, .out = 2 },
.{ .in = 1, .bit_count = 3, .out = 4 },
.{ .in = 1, .bit_count = 4, .out = 8 },
.{ .in = 1, .bit_count = 5, .out = 16 },
.{ .in = 17, .bit_count = 5, .out = 17 },
.{ .in = 257, .bit_count = 9, .out = 257 },
.{ .in = 29, .bit_count = 5, .out = 23 },
};
for (reverse_bits_tests) |h| {
var v = bitReverse(u16, h.in, h.bit_count);
try std.testing.expectEqual(h.out, v);
}
}