1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
|
const std = @import("std");
const builtin = @import("builtin");
const common = @import("common.zig");
pub const panic = common.panic;
comptime {
@export(__bswapsi2, .{ .name = "__bswapsi2", .linkage = common.linkage, .visibility = common.visibility });
@export(__bswapdi2, .{ .name = "__bswapdi2", .linkage = common.linkage, .visibility = common.visibility });
@export(__bswapti2, .{ .name = "__bswapti2", .linkage = common.linkage, .visibility = common.visibility });
}
// bswap - byteswap
// - bswapXi2 for unoptimized big and little endian
// ie for u32
// DE AD BE EF <- little|big endian
// FE BE AD DE <- big|little endian
// ff 00 00 00 >> 3*8 (leftmost byte)
// 00 ff 00 00 >> 1*8 (2nd left byte)
// 00 00 ff 00 << 1*8 (2n right byte)
// 00 00 00 ff << 3*8 (rightmost byte)
inline fn bswapXi2(comptime T: type, a: T) T {
switch (@bitSizeOf(T)) {
32 => {
// zig fmt: off
return (((a & 0xff000000) >> 24)
| ((a & 0x00ff0000) >> 8 )
| ((a & 0x0000ff00) << 8 )
| ((a & 0x000000ff) << 24));
// zig fmt: on
},
64 => {
// zig fmt: off
return (((a & 0xff00000000000000) >> 56)
| ((a & 0x00ff000000000000) >> 40 )
| ((a & 0x0000ff0000000000) >> 24 )
| ((a & 0x000000ff00000000) >> 8 )
| ((a & 0x00000000ff000000) << 8 )
| ((a & 0x0000000000ff0000) << 24 )
| ((a & 0x000000000000ff00) << 40 )
| ((a & 0x00000000000000ff) << 56));
// zig fmt: on
},
128 => {
// zig fmt: off
return (((a & 0xff000000000000000000000000000000) >> 120)
| ((a & 0x00ff0000000000000000000000000000) >> 104)
| ((a & 0x0000ff00000000000000000000000000) >> 88 )
| ((a & 0x000000ff000000000000000000000000) >> 72 )
| ((a & 0x00000000ff0000000000000000000000) >> 56 )
| ((a & 0x0000000000ff00000000000000000000) >> 40 )
| ((a & 0x000000000000ff000000000000000000) >> 24 )
| ((a & 0x00000000000000ff0000000000000000) >> 8 )
| ((a & 0x0000000000000000ff00000000000000) << 8 )
| ((a & 0x000000000000000000ff000000000000) << 24 )
| ((a & 0x00000000000000000000ff0000000000) << 40 )
| ((a & 0x0000000000000000000000ff00000000) << 56 )
| ((a & 0x000000000000000000000000ff000000) << 72 )
| ((a & 0x00000000000000000000000000ff0000) << 88 )
| ((a & 0x0000000000000000000000000000ff00) << 104)
| ((a & 0x000000000000000000000000000000ff) << 120));
// zig fmt: on
},
else => unreachable,
}
}
pub fn __bswapsi2(a: u32) callconv(.C) u32 {
return bswapXi2(u32, a);
}
pub fn __bswapdi2(a: u64) callconv(.C) u64 {
return bswapXi2(u64, a);
}
pub fn __bswapti2(a: u128) callconv(.C) u128 {
return bswapXi2(u128, a);
}
test {
_ = @import("bswapsi2_test.zig");
_ = @import("bswapdi2_test.zig");
_ = @import("bswapti2_test.zig");
}
|
