1const std = @import("std");
 2const builtin = @import("builtin");
 3const common = @import("common.zig");
 4
 5pub const panic = common.panic;
 6
 7comptime {
 8    @export(&__bitreversesi2, .{ .name = "__bitreversesi2", .linkage = common.linkage, .visibility = common.visibility });
 9    @export(&__bitreversedi2, .{ .name = "__bitreversedi2", .linkage = common.linkage, .visibility = common.visibility });
10    @export(&__bitreverseti2, .{ .name = "__bitreverseti2", .linkage = common.linkage, .visibility = common.visibility });
11}
12
13inline fn bitreverseXi2(comptime T: type, a: T) T {
14    switch (@bitSizeOf(T)) {
15        32 => {
16            var t: T = a;
17            t = ((t >> 1) & 0x55555555) | ((t & 0x55555555) << 1);
18            t = ((t >> 2) & 0x33333333) | ((t & 0x33333333) << 2);
19            t = ((t >> 4) & 0x0F0F0F0F) | ((t & 0x0F0F0F0F) << 4);
20            t = ((t >> 8) & 0x00FF00FF) | ((t & 0x00FF00FF) << 8);
21            t = (t >> 16) | (t << 16);
22            return t;
23        },
24        64 => {
25            var t: T = a;
26            t = ((t >> 1) & 0x5555555555555555) | ((t & 0x5555555555555555) << 1);
27            t = ((t >> 2) & 0x3333333333333333) | ((t & 0x3333333333333333) << 2);
28            t = ((t >> 4) & 0x0F0F0F0F0F0F0F0F) | ((t & 0x0F0F0F0F0F0F0F0F) << 4);
29            t = ((t >> 8) & 0x00FF00FF00FF00FF) | ((t & 0x00FF00FF00FF00FF) << 8);
30            t = ((t >> 16) & 0x0000FFFF0000FFFF) | ((t & 0x0000FFFF0000FFFF) << 16);
31            t = (t >> 32) | (t << 32);
32            return t;
33        },
34        128 => {
35            var t: T = a;
36            t = ((t >> 1) & 0x55555555555555555555555555555555) | ((t & 0x55555555555555555555555555555555) << 1);
37            t = ((t >> 2) & 0x33333333333333333333333333333333) | ((t & 0x33333333333333333333333333333333) << 2);
38            t = ((t >> 4) & 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F) | ((t & 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F) << 4);
39            t = ((t >> 8) & 0x00FF00FF00FF00FF00FF00FF00FF00FF) | ((t & 0x00FF00FF00FF00FF00FF00FF00FF00FF) << 8);
40            t = ((t >> 16) & 0x0000FFFF0000FFFF0000FFFF0000FFFF) | ((t & 0x0000FFFF0000FFFF0000FFFF0000FFFF) << 16);
41            t = ((t >> 32) & 0x00000000FFFFFFFF00000000FFFFFFFF) | ((t & 0x00000000FFFFFFFF00000000FFFFFFFF) << 32);
42            t = (t >> 64) | (t << 64);
43            return t;
44        },
45        else => unreachable,
46    }
47}
48
49pub fn __bitreversesi2(a: u32) callconv(.c) u32 {
50    return bitreverseXi2(u32, a);
51}
52
53pub fn __bitreversedi2(a: u64) callconv(.c) u64 {
54    return bitreverseXi2(u64, a);
55}
56
57pub fn __bitreverseti2(a: u128) callconv(.c) u128 {
58    return bitreverseXi2(u128, a);
59}
60
61test {
62    _ = @import("bitreversesi2_test.zig");
63    _ = @import("bitreversedi2_test.zig");
64    _ = @import("bitreverseti2_test.zig");
65}