33 lines
707 B
Rust
33 lines
707 B
Rust
const FP_ILOGBNAN: i32 = -1 - 0x7fffffff;
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const FP_ILOGB0: i32 = FP_ILOGBNAN;
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#[cfg_attr(assert_no_panic, no_panic::no_panic)]
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pub fn ilogb(x: f64) -> i32 {
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let mut i: u64 = x.to_bits();
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let e = ((i >> 52) & 0x7ff) as i32;
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if e == 0 {
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i <<= 12;
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if i == 0 {
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force_eval!(0.0 / 0.0);
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return FP_ILOGB0;
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}
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/* subnormal x */
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let mut e = -0x3ff;
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while (i >> 63) == 0 {
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e -= 1;
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i <<= 1;
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}
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e
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} else if e == 0x7ff {
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force_eval!(0.0 / 0.0);
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if (i << 12) != 0 {
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FP_ILOGBNAN
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} else {
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i32::MAX
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}
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} else {
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e - 0x3ff
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}
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}
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