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| </pre><pre class="rust"><code><span class="kw">use</span> <span class="ident">core</span>::{<span class="ident">f32</span>, <span class="ident">f64</span>}; |
| |
| <span class="kw">use</span> <span class="ident"><span class="kw">super</span>::scalbn</span>; |
| |
| <span class="kw">const</span> <span class="ident">ZEROINFNAN</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="number">0x7ff</span> <span class="op">-</span> <span class="number">0x3ff</span> <span class="op">-</span> <span class="number">52</span> <span class="op">-</span> <span class="number">1</span>; |
| |
| <span class="kw">struct</span> <span class="ident">Num</span> { |
| <span class="ident">m</span>: <span class="ident">u64</span>, |
| <span class="ident">e</span>: <span class="ident">i32</span>, |
| <span class="ident">sign</span>: <span class="ident">i32</span>, |
| } |
| |
| <span class="kw">fn</span> <span class="ident">normalize</span>(<span class="ident">x</span>: <span class="ident">f64</span>) -> <span class="ident">Num</span> { |
| <span class="kw">let</span> <span class="ident">x1p63</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">f64::from_bits</span>(<span class="number">0x43e0000000000000</span>); <span class="comment">// 0x1p63 === 2 ^ 63</span> |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ix</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">to_bits</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">e</span>: <span class="ident">i32</span> <span class="op">=</span> (<span class="ident">ix</span> <span class="op">></span><span class="op">></span> <span class="number">52</span>) <span class="kw">as</span> <span class="ident">i32</span>; |
| <span class="kw">let</span> <span class="ident">sign</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">e</span> <span class="op">&</span> <span class="number">0x800</span>; |
| <span class="ident">e</span> <span class="op">&=</span> <span class="number">0x7ff</span>; |
| <span class="kw">if</span> <span class="ident">e</span> <span class="op">==</span> <span class="number">0</span> { |
| <span class="ident">ix</span> <span class="op">=</span> (<span class="ident">x</span> <span class="op">*</span> <span class="ident">x1p63</span>).<span class="ident">to_bits</span>(); |
| <span class="ident">e</span> <span class="op">=</span> (<span class="ident">ix</span> <span class="op">></span><span class="op">></span> <span class="number">52</span>) <span class="kw">as</span> <span class="ident">i32</span> <span class="op">&</span> <span class="number">0x7ff</span>; |
| <span class="ident">e</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">e</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { <span class="ident">e</span> <span class="op">-</span> <span class="number">63</span> } <span class="kw">else</span> { <span class="number">0x800</span> }; |
| } |
| <span class="ident">ix</span> <span class="op">&=</span> (<span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="number">52</span>) <span class="op">-</span> <span class="number">1</span>; |
| <span class="ident">ix</span> <span class="op">|</span><span class="op">=</span> <span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="number">52</span>; |
| <span class="ident">ix</span> <span class="op"><</span><span class="op"><</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">e</span> <span class="op">-</span><span class="op">=</span> <span class="number">0x3ff</span> <span class="op">+</span> <span class="number">52</span> <span class="op">+</span> <span class="number">1</span>; |
| <span class="ident">Num</span> { <span class="ident">m</span>: <span class="ident">ix</span>, <span class="ident">e</span>, <span class="ident">sign</span> } |
| } |
| |
| <span class="kw">fn</span> <span class="ident">mul</span>(<span class="ident">x</span>: <span class="ident">u64</span>, <span class="ident">y</span>: <span class="ident">u64</span>) -> (<span class="ident">u64</span>, <span class="ident">u64</span>) { |
| <span class="kw">let</span> <span class="ident">t1</span>: <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">t2</span>: <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">t3</span>: <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">xlo</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="ident">x</span> <span class="kw">as</span> <span class="ident">u32</span> <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">xhi</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="ident">x</span> <span class="op">></span><span class="op">></span> <span class="number">32</span>; |
| <span class="kw">let</span> <span class="ident">ylo</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="ident">y</span> <span class="kw">as</span> <span class="ident">u32</span> <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">yhi</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">></span><span class="op">></span> <span class="number">32</span>; |
| |
| <span class="ident">t1</span> <span class="op">=</span> <span class="ident">xlo</span> <span class="op">*</span> <span class="ident">ylo</span>; |
| <span class="ident">t2</span> <span class="op">=</span> <span class="ident">xlo</span> <span class="op">*</span> <span class="ident">yhi</span> <span class="op">+</span> <span class="ident">xhi</span> <span class="op">*</span> <span class="ident">ylo</span>; |
| <span class="ident">t3</span> <span class="op">=</span> <span class="ident">xhi</span> <span class="op">*</span> <span class="ident">yhi</span>; |
| <span class="kw">let</span> <span class="ident">lo</span> <span class="op">=</span> <span class="ident">t1</span>.<span class="ident">wrapping_add</span>(<span class="ident">t2</span> <span class="op"><</span><span class="op"><</span> <span class="number">32</span>); |
| <span class="kw">let</span> <span class="ident">hi</span> <span class="op">=</span> <span class="ident">t3</span> <span class="op">+</span> (<span class="ident">t2</span> <span class="op">></span><span class="op">></span> <span class="number">32</span>) <span class="op">+</span> (<span class="ident">t1</span> <span class="op">></span> <span class="ident">lo</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| (<span class="ident">hi</span>, <span class="ident">lo</span>) |
| } |
| |
| <span class="doccomment">/// Floating multiply add (f64)</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Computes `(x*y)+z`, rounded as one ternary operation:</span> |
| <span class="doccomment">/// Computes the value (as if) to infinite precision and rounds once to the result format,</span> |
| <span class="doccomment">/// according to the rounding mode characterized by the value of FLT_ROUNDS.</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">all</span>(<span class="ident">test</span>, <span class="ident">assert_no_panic</span>), <span class="ident">no_panic::no_panic</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">fma</span>(<span class="ident">x</span>: <span class="ident">f64</span>, <span class="ident">y</span>: <span class="ident">f64</span>, <span class="ident">z</span>: <span class="ident">f64</span>) -> <span class="ident">f64</span> { |
| <span class="kw">let</span> <span class="ident">x1p63</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">f64::from_bits</span>(<span class="number">0x43e0000000000000</span>); <span class="comment">// 0x1p63 === 2 ^ 63</span> |
| <span class="kw">let</span> <span class="ident">x0_ffffff8p_63</span> <span class="op">=</span> <span class="ident">f64::from_bits</span>(<span class="number">0x3bfffffff0000000</span>); <span class="comment">// 0x0.ffffff8p-63</span> |
| |
| <span class="comment">/* normalize so top 10bits and last bit are 0 */</span> |
| <span class="kw">let</span> <span class="ident">nx</span> <span class="op">=</span> <span class="ident">normalize</span>(<span class="ident">x</span>); |
| <span class="kw">let</span> <span class="ident">ny</span> <span class="op">=</span> <span class="ident">normalize</span>(<span class="ident">y</span>); |
| <span class="kw">let</span> <span class="ident">nz</span> <span class="op">=</span> <span class="ident">normalize</span>(<span class="ident">z</span>); |
| |
| <span class="kw">if</span> <span class="ident">nx</span>.<span class="ident">e</span> <span class="op">></span><span class="op">=</span> <span class="ident">ZEROINFNAN</span> <span class="op">|</span><span class="op">|</span> <span class="ident">ny</span>.<span class="ident">e</span> <span class="op">></span><span class="op">=</span> <span class="ident">ZEROINFNAN</span> { |
| <span class="kw">return</span> <span class="ident">x</span> <span class="op">*</span> <span class="ident">y</span> <span class="op">+</span> <span class="ident">z</span>; |
| } |
| <span class="kw">if</span> <span class="ident">nz</span>.<span class="ident">e</span> <span class="op">></span><span class="op">=</span> <span class="ident">ZEROINFNAN</span> { |
| <span class="kw">if</span> <span class="ident">nz</span>.<span class="ident">e</span> <span class="op">></span> <span class="ident">ZEROINFNAN</span> { |
| <span class="comment">/* z==0 */</span> |
| <span class="kw">return</span> <span class="ident">x</span> <span class="op">*</span> <span class="ident">y</span> <span class="op">+</span> <span class="ident">z</span>; |
| } |
| <span class="kw">return</span> <span class="ident">z</span>; |
| } |
| |
| <span class="comment">/* mul: r = x*y */</span> |
| <span class="kw">let</span> <span class="ident">zhi</span>: <span class="ident">u64</span>; |
| <span class="kw">let</span> <span class="ident">zlo</span>: <span class="ident">u64</span>; |
| <span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">rhi</span>, <span class="kw-2">mut</span> <span class="ident">rlo</span>) <span class="op">=</span> <span class="ident">mul</span>(<span class="ident">nx</span>.<span class="ident">m</span>, <span class="ident">ny</span>.<span class="ident">m</span>); |
| <span class="comment">/* either top 20 or 21 bits of rhi and last 2 bits of rlo are 0 */</span> |
| |
| <span class="comment">/* align exponents */</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">e</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">nx</span>.<span class="ident">e</span> <span class="op">+</span> <span class="ident">ny</span>.<span class="ident">e</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">d</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">e</span> <span class="op">-</span> <span class="ident">e</span>; |
| <span class="comment">/* shift bits z<<=kz, r>>=kr, so kz+kr == d, set e = e+kr (== ez-kz) */</span> |
| <span class="kw">if</span> <span class="ident">d</span> <span class="op">></span> <span class="number">0</span> { |
| <span class="kw">if</span> <span class="ident">d</span> <span class="op"><</span> <span class="number">64</span> { |
| <span class="ident">zlo</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">m</span> <span class="op"><</span><span class="op"><</span> <span class="ident">d</span>; |
| <span class="ident">zhi</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">m</span> <span class="op">></span><span class="op">></span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>); |
| } <span class="kw">else</span> { |
| <span class="ident">zlo</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="ident">zhi</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">m</span>; |
| <span class="ident">e</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">e</span> <span class="op">-</span> <span class="number">64</span>; |
| <span class="ident">d</span> <span class="op">-</span><span class="op">=</span> <span class="number">64</span>; |
| <span class="kw">if</span> <span class="ident">d</span> <span class="op">==</span> <span class="number">0</span> { |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">d</span> <span class="op"><</span> <span class="number">64</span> { |
| <span class="ident">rlo</span> <span class="op">=</span> <span class="ident">rhi</span> <span class="op"><</span><span class="op"><</span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>) <span class="op">|</span> <span class="ident">rlo</span> <span class="op">></span><span class="op">></span> <span class="ident">d</span> <span class="op">|</span> ((<span class="ident">rlo</span> <span class="op"><</span><span class="op"><</span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>)) <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="ident">rhi</span> <span class="op">></span><span class="op">></span> <span class="ident">d</span>; |
| } <span class="kw">else</span> { |
| <span class="ident">rlo</span> <span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="number">0</span>; |
| } |
| } |
| } <span class="kw">else</span> { |
| <span class="ident">zhi</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="ident">d</span> <span class="op">=</span> <span class="op">-</span><span class="ident">d</span>; |
| <span class="kw">if</span> <span class="ident">d</span> <span class="op">==</span> <span class="number">0</span> { |
| <span class="ident">zlo</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">m</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">d</span> <span class="op"><</span> <span class="number">64</span> { |
| <span class="ident">zlo</span> <span class="op">=</span> <span class="ident">nz</span>.<span class="ident">m</span> <span class="op">></span><span class="op">></span> <span class="ident">d</span> <span class="op">|</span> ((<span class="ident">nz</span>.<span class="ident">m</span> <span class="op"><</span><span class="op"><</span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>)) <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| } <span class="kw">else</span> { |
| <span class="ident">zlo</span> <span class="op">=</span> <span class="number">1</span>; |
| } |
| } |
| |
| <span class="comment">/* add */</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">sign</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">nx</span>.<span class="ident">sign</span> <span class="op">^</span> <span class="ident">ny</span>.<span class="ident">sign</span>; |
| <span class="kw">let</span> <span class="ident">samesign</span>: <span class="ident">bool</span> <span class="op">=</span> (<span class="ident">sign</span> <span class="op">^</span> <span class="ident">nz</span>.<span class="ident">sign</span>) <span class="op">==</span> <span class="number">0</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">nonzero</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="number">1</span>; |
| <span class="kw">if</span> <span class="ident">samesign</span> { |
| <span class="comment">/* r += z */</span> |
| <span class="ident">rlo</span> <span class="op">=</span> <span class="ident">rlo</span>.<span class="ident">wrapping_add</span>(<span class="ident">zlo</span>); |
| <span class="ident">rhi</span> <span class="op">+</span><span class="op">=</span> <span class="ident">zhi</span> <span class="op">+</span> (<span class="ident">rlo</span> <span class="op"><</span> <span class="ident">zlo</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| } <span class="kw">else</span> { |
| <span class="comment">/* r -= z */</span> |
| <span class="kw">let</span> <span class="ident">t</span> <span class="op">=</span> <span class="ident">rlo</span>; |
| <span class="ident">rlo</span> <span class="op">=</span> <span class="ident">rlo</span>.<span class="ident">wrapping_sub</span>(<span class="ident">zlo</span>); |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="ident">rhi</span>.<span class="ident">wrapping_sub</span>(<span class="ident">zhi</span>.<span class="ident">wrapping_sub</span>((<span class="ident">t</span> <span class="op"><</span> <span class="ident">rlo</span>) <span class="kw">as</span> <span class="ident">u64</span>)); |
| <span class="kw">if</span> (<span class="ident">rhi</span> <span class="op">></span><span class="op">></span> <span class="number">63</span>) <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">rlo</span> <span class="op">=</span> (<span class="op">-</span>(<span class="ident">rlo</span> <span class="kw">as</span> <span class="ident">i64</span>)) <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="ident">rhi</span> <span class="op">=</span> (<span class="op">-</span>(<span class="ident">rhi</span> <span class="kw">as</span> <span class="ident">i64</span>)) <span class="kw">as</span> <span class="ident">u64</span> <span class="op">-</span> (<span class="ident">rlo</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="ident">sign</span> <span class="op">=</span> (<span class="ident">sign</span> <span class="op">==</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">i32</span>; |
| } |
| <span class="ident">nonzero</span> <span class="op">=</span> (<span class="ident">rhi</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">i32</span>; |
| } |
| |
| <span class="comment">/* set rhi to top 63bit of the result (last bit is sticky) */</span> |
| <span class="kw">if</span> <span class="ident">nonzero</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">e</span> <span class="op">+</span><span class="op">=</span> <span class="number">64</span>; |
| <span class="ident">d</span> <span class="op">=</span> <span class="ident">rhi</span>.<span class="ident">leading_zeros</span>() <span class="kw">as</span> <span class="ident">i32</span> <span class="op">-</span> <span class="number">1</span>; |
| <span class="comment">/* note: d > 0 */</span> |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="ident">rhi</span> <span class="op"><</span><span class="op"><</span> <span class="ident">d</span> <span class="op">|</span> <span class="ident">rlo</span> <span class="op">></span><span class="op">></span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>) <span class="op">|</span> ((<span class="ident">rlo</span> <span class="op"><</span><span class="op"><</span> <span class="ident">d</span>) <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u64</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">rlo</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">d</span> <span class="op">=</span> <span class="ident">rlo</span>.<span class="ident">leading_zeros</span>() <span class="kw">as</span> <span class="ident">i32</span> <span class="op">-</span> <span class="number">1</span>; |
| <span class="kw">if</span> <span class="ident">d</span> <span class="op"><</span> <span class="number">0</span> { |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="ident">rlo</span> <span class="op">></span><span class="op">></span> <span class="number">1</span> <span class="op">|</span> (<span class="ident">rlo</span> <span class="op">&</span> <span class="number">1</span>); |
| } <span class="kw">else</span> { |
| <span class="ident">rhi</span> <span class="op">=</span> <span class="ident">rlo</span> <span class="op"><</span><span class="op"><</span> <span class="ident">d</span>; |
| } |
| } <span class="kw">else</span> { |
| <span class="comment">/* exact +-0 */</span> |
| <span class="kw">return</span> <span class="ident">x</span> <span class="op">*</span> <span class="ident">y</span> <span class="op">+</span> <span class="ident">z</span>; |
| } |
| <span class="ident">e</span> <span class="op">-</span><span class="op">=</span> <span class="ident">d</span>; |
| |
| <span class="comment">/* convert to double */</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span>: <span class="ident">i64</span> <span class="op">=</span> <span class="ident">rhi</span> <span class="kw">as</span> <span class="ident">i64</span>; <span class="comment">/* i is in [1<<62,(1<<63)-1] */</span> |
| <span class="kw">if</span> <span class="ident">sign</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">i</span> <span class="op">=</span> <span class="op">-</span><span class="ident">i</span>; |
| } |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">r</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">i</span> <span class="kw">as</span> <span class="ident">f64</span>; <span class="comment">/* |r| is in [0x1p62,0x1p63] */</span> |
| |
| <span class="kw">if</span> <span class="ident">e</span> <span class="op"><</span> <span class="op">-</span><span class="number">1022</span> <span class="op">-</span> <span class="number">62</span> { |
| <span class="comment">/* result is subnormal before rounding */</span> |
| <span class="kw">if</span> <span class="ident">e</span> <span class="op">==</span> <span class="op">-</span><span class="number">1022</span> <span class="op">-</span> <span class="number">63</span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">c</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">x1p63</span>; |
| <span class="kw">if</span> <span class="ident">sign</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">c</span> <span class="op">=</span> <span class="op">-</span><span class="ident">c</span>; |
| } |
| <span class="kw">if</span> <span class="ident">r</span> <span class="op">==</span> <span class="ident">c</span> { |
| <span class="comment">/* min normal after rounding, underflow depends |
| on arch behaviour which can be imitated by |
| a double to float conversion */</span> |
| <span class="kw">let</span> <span class="ident">fltmin</span>: <span class="ident">f32</span> <span class="op">=</span> (<span class="ident">x0_ffffff8p_63</span> <span class="op">*</span> <span class="ident">f32::MIN_POSITIVE</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="ident">r</span>) <span class="kw">as</span> <span class="ident">f32</span>; |
| <span class="kw">return</span> <span class="ident">f64::MIN_POSITIVE</span> <span class="op">/</span> <span class="ident">f32::MIN_POSITIVE</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="ident">fltmin</span> <span class="kw">as</span> <span class="ident">f64</span>; |
| } |
| <span class="comment">/* one bit is lost when scaled, add another top bit to |
| only round once at conversion if it is inexact */</span> |
| <span class="kw">if</span> (<span class="ident">rhi</span> <span class="op"><</span><span class="op"><</span> <span class="number">53</span>) <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">i</span> <span class="op">=</span> (<span class="ident">rhi</span> <span class="op">></span><span class="op">></span> <span class="number">1</span> <span class="op">|</span> (<span class="ident">rhi</span> <span class="op">&</span> <span class="number">1</span>) <span class="op">|</span> <span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="number">62</span>) <span class="kw">as</span> <span class="ident">i64</span>; |
| <span class="kw">if</span> <span class="ident">sign</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">i</span> <span class="op">=</span> <span class="op">-</span><span class="ident">i</span>; |
| } |
| <span class="ident">r</span> <span class="op">=</span> <span class="ident">i</span> <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="ident">r</span> <span class="op">=</span> <span class="number">2.</span> <span class="op">*</span> <span class="ident">r</span> <span class="op">-</span> <span class="ident">c</span>; <span class="comment">/* remove top bit */</span> |
| |
| <span class="comment">/* raise underflow portably, such that it |
| cannot be optimized away */</span> |
| { |
| <span class="kw">let</span> <span class="ident">tiny</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">f64::MIN_POSITIVE</span> <span class="op">/</span> <span class="ident">f32::MIN_POSITIVE</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="ident">r</span>; |
| <span class="ident">r</span> <span class="op">+</span><span class="op">=</span> (<span class="ident">tiny</span> <span class="op">*</span> <span class="ident">tiny</span>) <span class="op">*</span> (<span class="ident">r</span> <span class="op">-</span> <span class="ident">r</span>); |
| } |
| } |
| } <span class="kw">else</span> { |
| <span class="comment">/* only round once when scaled */</span> |
| <span class="ident">d</span> <span class="op">=</span> <span class="number">10</span>; |
| <span class="ident">i</span> <span class="op">=</span> ((<span class="ident">rhi</span> <span class="op">></span><span class="op">></span> <span class="ident">d</span> <span class="op">|</span> ((<span class="ident">rhi</span> <span class="op"><</span><span class="op"><</span> (<span class="number">64</span> <span class="op">-</span> <span class="ident">d</span>)) <span class="op">!</span><span class="op">=</span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u64</span>) <span class="op"><</span><span class="op"><</span> <span class="ident">d</span>) <span class="kw">as</span> <span class="ident">i64</span>; |
| <span class="kw">if</span> <span class="ident">sign</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="ident">i</span> <span class="op">=</span> <span class="op">-</span><span class="ident">i</span>; |
| } |
| <span class="ident">r</span> <span class="op">=</span> <span class="ident">i</span> <span class="kw">as</span> <span class="ident">f64</span>; |
| } |
| } |
| <span class="ident">scalbn</span>(<span class="ident">r</span>, <span class="ident">e</span>) |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">tests</span> { |
| <span class="kw">use</span> <span class="kw">super</span>::<span class="kw-2">*</span>; |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">fma_segfault</span>() { |
| <span class="comment">// These two inputs cause fma to segfault on release due to overflow:</span> |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">fma</span>( |
| <span class="op">-</span><span class="number">0.0000000000000002220446049250313</span>, |
| <span class="op">-</span><span class="number">0.0000000000000002220446049250313</span>, |
| <span class="op">-</span><span class="number">0.0000000000000002220446049250313</span> |
| ), |
| <span class="op">-</span><span class="number">0.00000000000000022204460492503126</span>, |
| ); |
| |
| <span class="macro">assert_eq!</span>(<span class="ident">fma</span>(<span class="op">-</span><span class="number">0.992</span>, <span class="op">-</span><span class="number">0.992</span>, <span class="op">-</span><span class="number">0.992</span>), <span class="op">-</span><span class="number">0.00793599999988632</span>,); |
| } |
| } |
| </code></pre></div> |
| </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="libm" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
| </body></html> |
