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78 lines
2.2 KiB
78 lines
2.2 KiB
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#include <stdbool.h>
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#include <stdint.h>
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#include "platform.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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float32_t f32_roundToInt( float32_t a, int_fast8_t roundingMode, bool exact )
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{
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union ui32_f32 uA;
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uint_fast32_t uiA;
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int_fast16_t expA;
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uint_fast32_t uiZ;
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bool signA;
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uint_fast32_t lastBitMask, roundBitsMask;
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union ui32_f32 uZ;
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uA.f = a;
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uiA = uA.ui;
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expA = expF32UI( uiA );
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if ( 0x96 <= expA ) {
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if ( ( expA == 0xFF ) && fracF32UI( uiA ) ) {
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uiZ = softfloat_propagateNaNF32UI( uiA, 0 );
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goto uiZ;
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}
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return a;
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}
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if ( expA <= 0x7E ) {
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if ( ! (uint32_t) ( uiA<<1 ) ) return a;
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if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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signA = signF32UI( uiA );
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switch ( roundingMode ) {
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case softfloat_round_nearest_even:
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if ( ( expA == 0x7E ) && fracF32UI( uiA ) ) {
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uiZ = packToF32UI( signA, 0x7F, 0 );
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goto uiZ;
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}
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break;
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case softfloat_round_min:
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uiZ = signA ? 0xBF800000 : 0;
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goto uiZ;
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case softfloat_round_max:
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uiZ = signA ? 0x80000000 : 0x3F800000;
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goto uiZ;
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case softfloat_round_nearest_maxMag:
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if ( expA == 0x7E ) {
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uiZ = packToF32UI( signA, 0x7F, 0 );
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goto uiZ;
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}
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break;
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}
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uiZ = packToF32UI( signA, 0, 0 );
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goto uiZ;
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}
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lastBitMask = (uint_fast32_t) 1<<( 0x96 - expA );
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roundBitsMask = lastBitMask - 1;
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uiZ = uiA;
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if ( roundingMode == softfloat_round_nearest_maxMag ) {
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uiZ += lastBitMask>>1;
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} else if ( roundingMode == softfloat_round_nearest_even ) {
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uiZ += lastBitMask>>1;
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if ( ! ( uiZ & roundBitsMask ) ) uiZ &= ~ lastBitMask;
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} else if ( roundingMode != softfloat_round_minMag ) {
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if ( signF32UI( uiZ ) ^ ( roundingMode == softfloat_round_max ) ) {
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uiZ += roundBitsMask;
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}
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}
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uiZ &= ~ roundBitsMask;
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if ( exact && ( uiZ != uiA ) ) {
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softfloat_exceptionFlags |= softfloat_flag_inexact;
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}
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uiZ:
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uZ.ui = uiZ;
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return uZ.f;
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}
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