29 lines
792 B
Zig
29 lines
792 B
Zig
const builtin = @import("builtin");
|
|
const is_test = builtin.is_test;
|
|
const std = @import("std");
|
|
|
|
pub extern fn __floatunditf(a: u128) 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.bit_count - 1) - @clz(u128, a);
|
|
const shift = mantissa_bits - @intCast(u7, exp);
|
|
|
|
var result: u128 align(16) = (a << shift) ^ implicit_bit;
|
|
result += (@intCast(u128, exp) + exponent_bias) << mantissa_bits;
|
|
|
|
return @bitCast(f128, result);
|
|
}
|
|
|
|
test "import floatunditf" {
|
|
_ = @import("floatunditf_test.zig");
|
|
}
|