zig/lib/std/special/compiler_rt/floatunditf.zig
Andrew Kelley a2ff3a13fe std, compiler-rt: remove test names where applicable
Tests with no names are executed when using `zig test` regardless of the
`--test-filter` used. Non-named tests should be used when simply
importing unit tests from another file. This allows `zig test` to find
all the appropriate tests, even when using `--test-filter`.
2021-09-01 17:54:06 -07:00

29 lines
763 B
Zig

const builtin = @import("builtin");
const is_test = builtin.is_test;
const std = @import("std");
pub fn __floatunditf(a: u64) callconv(.C) f128 {
@setRuntimeSafety(is_test);
if (a == 0) {
return 0;
}
const mantissa_bits = std.math.floatMantissaBits(f128);
const exponent_bits = std.math.floatExponentBits(f128);
const exponent_bias = (1 << (exponent_bits - 1)) - 1;
const implicit_bit = 1 << mantissa_bits;
const exp: u128 = (64 - 1) - @clz(u64, a);
const shift: u7 = mantissa_bits - @intCast(u7, exp);
var result: u128 = (@intCast(u128, a) << shift) ^ implicit_bit;
result += (exp + exponent_bias) << mantissa_bits;
return @bitCast(f128, result);
}
test {
_ = @import("floatunditf_test.zig");
}