zig/lib/compiler_rt/bswap.zig
Luuk de Gram 30f2bb8464
compiler-rt: Set the symbol visibility
When we're compiling compiler_rt for any WebAssembly target, we do
not want to expose all the compiler-rt functions to the host runtime.
By setting the visibility of all exports to `hidden`, we allow the
linker to resolve the symbols during linktime, while not expose the
functions to the host runtime. This also means the linker can
properly garbage collect any compiler-rt function that does not get
resolved. The symbol visibility for all target remains the same as
before: `default`.
2022-12-28 14:57:17 +01:00

86 lines
3.2 KiB
Zig

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");
}