156 lines
6.0 KiB
C
156 lines
6.0 KiB
C
/*============================================================================
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This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
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Package, Release 3e, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014, 2015, 2016 The Regents of the University of
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California. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3. Neither the name of the University nor the names of its contributors may
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be used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
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DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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=============================================================================*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "internals.h"
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#include "specialize.h"
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#include "softfloat.h"
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/*----------------------------------------------------------------------------
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| Return the result of a floating point scale of the single-precision floating
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| point value `a' by multiplying it by 2 power of the single-precision
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| floating point value 'b' converted to integral value. If the result cannot
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| be represented in single precision, then the proper overflow response (for
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| positive scaling operand), or the proper underflow response (for negative
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| scaling operand) is issued. The operation is performed according to the
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| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
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*----------------------------------------------------------------------------*/
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float32 f32_scalef(float32 a, float32 b, struct softfloat_status_t *status)
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{
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bool signA;
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int16_t expA;
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uint32_t sigA;
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bool signB;
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int16_t expB;
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uint32_t sigB;
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int shiftCount;
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int scale = 0;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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signA = signF32UI(a);
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expA = expF32UI(a);
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sigA = fracF32UI(a);
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signB = signF32UI(b);
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expB = expF32UI(b);
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sigB = fracF32UI(b);
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (expB == 0xFF) {
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if (sigB) return softfloat_propagateNaNF32UI(a, b, status);
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (softfloat_denormalsAreZeros(status)) {
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if (!expA) sigA = 0;
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if (!expB) sigB = 0;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (expA == 0xFF) {
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if (sigA) {
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int aIsSignalingNaN = (sigA & 0x00400000) == 0;
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if (aIsSignalingNaN || expB != 0xFF || sigB)
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return softfloat_propagateNaNF32UI(a, b, status);
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return signB ? 0 : packToF32UI(0, 0xFF, 0);
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}
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if (expB == 0xFF && signB) {
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softfloat_raiseFlags(status, softfloat_flag_invalid);
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return defaultNaNF32UI;
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}
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return a;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (! expA) {
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if (! sigA) {
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if (expB == 0xFF && ! signB) {
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softfloat_raiseFlags(status, softfloat_flag_invalid);
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return defaultNaNF32UI;
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}
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return packToF32UI(signA, 0, 0);
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}
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ((expB | sigB) == 0) return a;
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if (expB == 0xFF) {
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if (signB) return packToF32UI(signA, 0, 0);
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return packToF32UI(signA, 0xFF, 0);
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}
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if (expB >= 0x8E) {
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// handle obvious overflow/underflow result
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return softfloat_roundPackToF32(signA, signB ? -0x7F : 0xFF, sigA, status);
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (expB <= 0x7E) {
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if (! expB)
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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scale = -signB;
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}
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else {
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shiftCount = expB - 0x9E;
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sigB = (sigB | 0x800000)<<8;
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scale = sigB>>(-shiftCount);
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if (signB) {
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if ((uint32_t) (sigB<<(shiftCount & 31))) scale++;
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scale = -scale;
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}
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if (scale > 0x200) scale = 0x200;
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if (scale < -0x200) scale = -0x200;
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}
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if (expA != 0) {
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sigA |= 0x00800000;
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} else {
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expA++;
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}
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expA += scale - 1;
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sigA <<= 7;
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return softfloat_normRoundPackToF32(signA, expA, sigA, status);
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}
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