mirror of
https://codeberg.org/ziglang/zig.git
synced 2025-12-06 05:44:20 +00:00
41dd2beaac
* unify the logic for exporting math functions from compiler-rt,
with the appropriate suffixes and prefixes.
- add all missing f128 and f80 exports. Functions with missing
implementations call other functions and have TODO comments.
- also add f16 functions
* move math functions from freestanding libc to compiler-rt (#7265)
* enable all the f128 and f80 code in the stage2 compiler and behavior
tests (#11161).
* update std lib to use builtins rather than `std.math`.
39 lines
1.1 KiB
Zig
39 lines
1.1 KiB
Zig
const std = @import("../std.zig");
|
|
const math = std.math;
|
|
const expect = std.testing.expect;
|
|
|
|
/// Returns the base-2 logarithm of x.
|
|
///
|
|
/// Special Cases:
|
|
/// - log2(+inf) = +inf
|
|
/// - log2(0) = -inf
|
|
/// - log2(x) = nan if x < 0
|
|
/// - log2(nan) = nan
|
|
pub fn log2(x: anytype) @TypeOf(x) {
|
|
const T = @TypeOf(x);
|
|
switch (@typeInfo(T)) {
|
|
.ComptimeFloat => {
|
|
return @as(comptime_float, @log2(x));
|
|
},
|
|
.Float => return @log2(x),
|
|
.ComptimeInt => comptime {
|
|
var result = 0;
|
|
var x_shifted = x;
|
|
while (b: {
|
|
x_shifted >>= 1;
|
|
break :b x_shifted != 0;
|
|
}) : (result += 1) {}
|
|
return result;
|
|
},
|
|
.Int => |IntType| switch (IntType.signedness) {
|
|
.signed => @compileError("log2 not implemented for signed integers"),
|
|
.unsigned => return math.log2_int(T, x),
|
|
},
|
|
else => @compileError("log2 not implemented for " ++ @typeName(T)),
|
|
}
|
|
}
|
|
|
|
test "log2" {
|
|
try expect(log2(@as(f32, 0.2)) == @log2(0.2));
|
|
try expect(log2(@as(f64, 0.2)) == @log2(0.2));
|
|
}
|