diff options
Diffstat (limited to 'softfloat/f16_rem.c')
| -rw-r--r-- | softfloat/f16_rem.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/softfloat/f16_rem.c b/softfloat/f16_rem.c new file mode 100644 index 0000000..76a0de6 --- /dev/null +++ b/softfloat/f16_rem.c @@ -0,0 +1,171 @@ + +/*============================================================================ + +This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic +Package, Release 3e, by John R. Hauser. + +Copyright 2011, 2012, 2013, 2014, 2015, 2016 The Regents of the University of +California. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright notice, + this list of conditions, and the following disclaimer. + + 2. Redistributions in binary form must reproduce the above copyright notice, + this list of conditions, and the following disclaimer in the documentation + and/or other materials provided with the distribution. + + 3. Neither the name of the University nor the names of its contributors may + be used to endorse or promote products derived from this software without + specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY +EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE +DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY +DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +=============================================================================*/ + +#include <stdbool.h> +#include <stdint.h> +#include "platform.h" +#include "internals.h" +#include "specialize.h" +#include "softfloat.h" + +float16_t f16_rem( float16_t a, float16_t b ) +{ + union ui16_f16 uA; + uint_fast16_t uiA; + bool signA; + int_fast8_t expA; + uint_fast16_t sigA; + union ui16_f16 uB; + uint_fast16_t uiB; + int_fast8_t expB; + uint_fast16_t sigB; + struct exp8_sig16 normExpSig; + uint16_t rem; + int_fast8_t expDiff; + uint_fast16_t q; + uint32_t recip32, q32; + uint16_t altRem, meanRem; + bool signRem; + uint_fast16_t uiZ; + union ui16_f16 uZ; + + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + uA.f = a; + uiA = uA.ui; + signA = signF16UI( uiA ); + expA = expF16UI( uiA ); + sigA = fracF16UI( uiA ); + uB.f = b; + uiB = uB.ui; + expB = expF16UI( uiB ); + sigB = fracF16UI( uiB ); + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + if ( expA == 0x1F ) { + if ( sigA || ((expB == 0x1F) && sigB) ) goto propagateNaN; + goto invalid; + } + if ( expB == 0x1F ) { + if ( sigB ) goto propagateNaN; + return a; + } + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + if ( ! expB ) { + if ( ! sigB ) goto invalid; + normExpSig = softfloat_normSubnormalF16Sig( sigB ); + expB = normExpSig.exp; + sigB = normExpSig.sig; + } + if ( ! expA ) { + if ( ! sigA ) return a; + normExpSig = softfloat_normSubnormalF16Sig( sigA ); + expA = normExpSig.exp; + sigA = normExpSig.sig; + } + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + rem = sigA | 0x0400; + sigB |= 0x0400; + expDiff = expA - expB; + if ( expDiff < 1 ) { + if ( expDiff < -1 ) return a; + sigB <<= 3; + if ( expDiff ) { + rem <<= 2; + q = 0; + } else { + rem <<= 3; + q = (sigB <= rem); + if ( q ) rem -= sigB; + } + } else { + recip32 = softfloat_approxRecip32_1( (uint_fast32_t) sigB<<21 ); + /*-------------------------------------------------------------------- + | Changing the shift of `rem' here requires also changing the initial + | subtraction from `expDiff'. + *--------------------------------------------------------------------*/ + rem <<= 4; + expDiff -= 31; + /*-------------------------------------------------------------------- + | The scale of `sigB' affects how many bits are obtained during each + | cycle of the loop. Currently this is 29 bits per loop iteration, + | which is believed to be the maximum possible. + *--------------------------------------------------------------------*/ + sigB <<= 3; + for (;;) { + q32 = (rem * (uint_fast64_t) recip32)>>16; + if ( expDiff < 0 ) break; + rem = -((uint_fast16_t) q32 * sigB); + expDiff -= 29; + } + /*-------------------------------------------------------------------- + | (`expDiff' cannot be less than -30 here.) + *--------------------------------------------------------------------*/ + q32 >>= ~expDiff & 31; + q = q32; + rem = (rem<<(expDiff + 30)) - q * sigB; + } + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + do { + altRem = rem; + ++q; + rem -= sigB; + } while ( ! (rem & 0x8000) ); + meanRem = rem + altRem; + if ( (meanRem & 0x8000) || (! meanRem && (q & 1)) ) rem = altRem; + signRem = signA; + if ( 0x8000 <= rem ) { + signRem = ! signRem; + rem = -rem; + } + return softfloat_normRoundPackToF16( signRem, expB, rem ); + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + propagateNaN: + uiZ = softfloat_propagateNaNF16UI( uiA, uiB ); + goto uiZ; + invalid: + softfloat_raiseFlags( softfloat_flag_invalid ); + uiZ = defaultNaNF16UI; + uiZ: + uZ.ui = uiZ; + return uZ.f; + +} + |