| |
| /*============================================================================ |
| |
| This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic |
| Package, Release 3, by John R. Hauser. |
| |
| Copyright 2011, 2012, 2013, 2014 The Regents of the University of California |
| (Regents). All Rights Reserved. Redistribution and use in source and binary |
| forms, with or without modification, are permitted provided that the following |
| conditions are met: |
| |
| Redistributions of source code must retain the above copyright notice, |
| this list of conditions, and the following two paragraphs of disclaimer. |
| Redistributions in binary form must reproduce the above copyright notice, |
| this list of conditions, and the following two paragraphs of disclaimer in the |
| documentation and/or other materials provided with the distribution. Neither |
| the name of the Regents nor the names of its contributors may be used to |
| endorse or promote products derived from this software without specific prior |
| written permission. |
| |
| IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, |
| SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING |
| OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS |
| BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED |
| TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED |
| HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE |
| MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. |
| |
| =============================================================================*/ |
| |
| #include <stdint.h> |
| #include "platform.h" |
| #include "primitives.h" |
| |
| #ifndef softfloat_approxRecipSqrt32_1 |
| |
| uint32_t softfloat_approxRecipSqrt32_1( unsigned int oddExpA, uint32_t a ) |
| { |
| int index; |
| uint16_t eps; |
| static const uint16_t k0s[] = { |
| 0xB4C9, 0xFFAB, 0xAA7D, 0xF11C, 0xA1C5, 0xE4C7, 0x9A43, 0xDA29, |
| 0x93B5, 0xD0E5, 0x8DED, 0xC8B7, 0x88C6, 0xC16D, 0x8424, 0xBAE1 |
| }; |
| static const uint16_t k1s[] = { |
| 0xA5A5, 0xEA42, 0x8C21, 0xC62D, 0x788F, 0xAA7F, 0x6928, 0x94B6, |
| 0x5CC7, 0x8335, 0x52A6, 0x74E2, 0x4A3E, 0x68FE, 0x432B, 0x5EFD |
| }; |
| uint16_t r0; |
| uint_fast32_t ESqrR0; |
| uint32_t delta0; |
| uint_fast32_t r; |
| uint32_t sqrDelta0; |
| |
| index = (a>>27 & 0xE) + oddExpA; |
| eps = (uint16_t) (a>>12); |
| r0 = k0s[index] - ((k1s[index] * (uint_fast32_t) eps)>>20); |
| ESqrR0 = (uint_fast32_t) r0 * r0; |
| if ( ! oddExpA ) ESqrR0 <<= 1; |
| delta0 = ~(uint_fast32_t) (((uint32_t) ESqrR0 * (uint_fast64_t) a)>>23); |
| r = ((uint_fast32_t) r0<<16) + ((r0 * (uint_fast64_t) delta0)>>25); |
| sqrDelta0 = ((uint_fast64_t) delta0 * delta0)>>32; |
| r += ((uint32_t) ((r>>1) + (r>>3) - ((uint_fast32_t) r0<<14)) |
| * (uint_fast64_t) sqrDelta0) |
| >>48; |
| if ( ! (r & 0x80000000) ) r = 0x80000000; |
| return r; |
| |
| } |
| |
| #endif |
| |