0556a2ba53
Finishes cleanups that I started in other commits in this branch. * Use common.linkage for all exports instead of redoing the logic in each file. * Remove pointless `@setRuntimeSafety` calls. * Avoid redundantly exporting multiple versions of functions. For example, if PPC wants `ceilf128` then don't also export `ceilq`; similarly if ARM wants `__aeabi_ddiv` then don't also export `__divdf3`. * Use `inline` for helper functions instead of making inline calls at callsites.
50 lines
1.4 KiB
Zig
50 lines
1.4 KiB
Zig
//! parity - if number of bits set is even => 0, else => 1
|
|
//! - pariytXi2_generic for big and little endian
|
|
|
|
const std = @import("std");
|
|
const builtin = @import("builtin");
|
|
const common = @import("common.zig");
|
|
|
|
pub const panic = common.panic;
|
|
|
|
comptime {
|
|
@export(__paritysi2, .{ .name = "__paritysi2", .linkage = common.linkage });
|
|
@export(__paritydi2, .{ .name = "__paritydi2", .linkage = common.linkage });
|
|
@export(__parityti2, .{ .name = "__parityti2", .linkage = common.linkage });
|
|
}
|
|
|
|
pub fn __paritysi2(a: i32) callconv(.C) i32 {
|
|
return parityXi2(i32, a);
|
|
}
|
|
|
|
pub fn __paritydi2(a: i64) callconv(.C) i32 {
|
|
return parityXi2(i64, a);
|
|
}
|
|
|
|
pub fn __parityti2(a: i128) callconv(.C) i32 {
|
|
return parityXi2(i128, a);
|
|
}
|
|
|
|
inline fn parityXi2(comptime T: type, a: T) i32 {
|
|
var x = switch (@bitSizeOf(T)) {
|
|
32 => @bitCast(u32, a),
|
|
64 => @bitCast(u64, a),
|
|
128 => @bitCast(u128, a),
|
|
else => unreachable,
|
|
};
|
|
// Bit Twiddling Hacks: Compute parity in parallel
|
|
comptime var shift: u8 = @bitSizeOf(T) / 2;
|
|
inline while (shift > 2) {
|
|
x ^= x >> shift;
|
|
shift = shift >> 1;
|
|
}
|
|
x &= 0xf;
|
|
return (@intCast(u16, 0x6996) >> @intCast(u4, x)) & 1; // optimization for >>2 and >>1
|
|
}
|
|
|
|
test {
|
|
_ = @import("paritysi2_test.zig");
|
|
_ = @import("paritydi2_test.zig");
|
|
_ = @import("parityti2_test.zig");
|
|
}
|