29 lines
786 B
Zig
29 lines
786 B
Zig
const builtin = @import("builtin");
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const is_test = builtin.is_test;
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const std = @import("std");
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pub extern fn __floatunditf(a: u128) f128 {
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@setRuntimeSafety(is_test);
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if (a == 0) {
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return 0;
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}
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const mantissa_bits = std.math.floatMantissaBits(f128);
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const exponent_bits = std.math.floatExponentBits(f128);
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const exponent_bias = (1 << (exponent_bits - 1)) - 1;
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const implicit_bit = 1 << mantissa_bits;
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const exp = (u128.bit_count - 1) - @clz(a);
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const shift = mantissa_bits - @intCast(u7, exp);
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var result: u128 align(16) = (a << shift) ^ implicit_bit;
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result += (@intCast(u128, exp) + exponent_bias) << mantissa_bits;
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return @bitCast(f128, result);
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}
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test "import floatunditf" {
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_ = @import("floatunditf_test.zig");
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}
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