| |
| /*============================================================================ |
| |
| 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 <stdbool.h> |
| #include <stdint.h> |
| #include "platform.h" |
| #include "internals.h" |
| #include "specialize.h" |
| #include "softfloat.h" |
| |
| float64_t f64_rem( float64_t a, float64_t b ) |
| { |
| union ui64_f64 uA; |
| uint_fast64_t uiA; |
| bool signA; |
| int_fast16_t expA; |
| uint_fast64_t sigA; |
| union ui64_f64 uB; |
| uint_fast64_t uiB; |
| int_fast16_t expB; |
| uint_fast64_t sigB; |
| struct exp16_sig64 normExpSig; |
| uint_fast64_t rem; |
| int_fast16_t expDiff; |
| uint32_t q, recip32; |
| uint_fast64_t q64, altRem; |
| uint64_t meanRem; |
| bool signRem; |
| uint_fast64_t uiZ; |
| union ui64_f64 uZ; |
| |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| uA.f = a; |
| uiA = uA.ui; |
| signA = signF64UI( uiA ); |
| expA = expF64UI( uiA ); |
| sigA = fracF64UI( uiA ); |
| uB.f = b; |
| uiB = uB.ui; |
| expB = expF64UI( uiB ); |
| sigB = fracF64UI( uiB ); |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| if ( expA == 0x7FF ) { |
| if ( sigA || ((expB == 0x7FF) && sigB) ) goto propagateNaN; |
| goto invalid; |
| } |
| if ( expB == 0x7FF ) { |
| if ( sigB ) goto propagateNaN; |
| return a; |
| } |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| if ( expA < expB - 1 ) return a; |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| if ( ! expB ) { |
| if ( ! sigB ) goto invalid; |
| normExpSig = softfloat_normSubnormalF64Sig( sigB ); |
| expB = normExpSig.exp; |
| sigB = normExpSig.sig; |
| } |
| if ( ! expA ) { |
| if ( ! sigA ) return a; |
| normExpSig = softfloat_normSubnormalF64Sig( sigA ); |
| expA = normExpSig.exp; |
| sigA = normExpSig.sig; |
| } |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| rem = sigA | UINT64_C( 0x0010000000000000 ); |
| sigB |= UINT64_C( 0x0010000000000000 ); |
| expDiff = expA - expB; |
| if ( expDiff < 1 ) { |
| if ( expDiff < -1 ) return a; |
| sigB <<= 9; |
| if ( expDiff ) { |
| rem <<= 8; |
| q = 0; |
| } else { |
| rem <<= 9; |
| q = (sigB <= rem); |
| if ( q ) rem -= sigB; |
| } |
| } else { |
| recip32 = softfloat_approxRecip32_1( sigB>>21 ); |
| /*-------------------------------------------------------------------- |
| | Changing the shift of `rem' here requires also changing the initial |
| | subtraction from `expDiff'. |
| *--------------------------------------------------------------------*/ |
| rem <<= 9; |
| expDiff -= 30; |
| /*-------------------------------------------------------------------- |
| | The scale of `sigB' affects how many bits are obtained during each |
| | cycle of the loop. Currently this is 29 bits per loop iteration, |
| | the maximum possible. |
| *--------------------------------------------------------------------*/ |
| sigB <<= 9; |
| for (;;) { |
| q64 = (uint32_t) (rem>>32) * (uint_fast64_t) recip32; |
| if ( expDiff < 0 ) break; |
| q = (q64 + 0x80000000)>>32; |
| #ifdef SOFTFLOAT_FAST_INT64 |
| rem <<= 29; |
| #else |
| rem = (uint_fast64_t) (uint32_t) (rem>>3)<<32; |
| #endif |
| rem -= q * (uint64_t) sigB; |
| if ( rem & UINT64_C( 0x8000000000000000 ) ) rem += sigB; |
| expDiff -= 29; |
| } |
| /*-------------------------------------------------------------------- |
| | (`expDiff' cannot be less than -29 here.) |
| *--------------------------------------------------------------------*/ |
| q = (uint32_t) (q64>>32)>>(~expDiff & 31); |
| rem = (rem<<(expDiff + 30)) - q * (uint64_t) sigB; |
| if ( rem & UINT64_C( 0x8000000000000000 ) ) { |
| altRem = rem + sigB; |
| goto selectRem; |
| } |
| } |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| do { |
| altRem = rem; |
| ++q; |
| rem -= sigB; |
| } while ( ! (rem & UINT64_C( 0x8000000000000000 )) ); |
| selectRem: |
| meanRem = rem + altRem; |
| if ( |
| (meanRem & UINT64_C( 0x8000000000000000 )) || (! meanRem && (q & 1)) |
| ) { |
| rem = altRem; |
| } |
| signRem = signA; |
| if ( rem & UINT64_C( 0x8000000000000000 ) ) { |
| signRem = ! signRem; |
| rem = -rem; |
| } |
| return softfloat_normRoundPackToF64( signRem, expB, rem ); |
| /*------------------------------------------------------------------------ |
| *------------------------------------------------------------------------*/ |
| propagateNaN: |
| uiZ = softfloat_propagateNaNF64UI( uiA, uiB ); |
| goto uiZ; |
| invalid: |
| softfloat_raiseFlags( softfloat_flag_invalid ); |
| uiZ = defaultNaNF64UI; |
| uiZ: |
| uZ.ui = uiZ; |
| return uZ.f; |
| |
| } |
| |