| 1 | /*
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| 2 | * Copyright (C) 2005 Josef Cejka
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | #include<sftypes.h>
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| 30 | #include<common.h>
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| 31 |
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| 32 | /** Take fraction shifted by 10 bits to left, round it, normalize it and detect exceptions
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| 33 | * @param exp exponent with bias
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| 34 | * @param cfrac fraction shifted 10 places left with added hidden bit
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| 35 | * @return valied float64
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| 36 | */
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| 37 | float64 finishFloat64(__s32 cexp, __u64 cfrac, char sign)
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| 38 | {
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| 39 | float64 result;
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| 40 |
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| 41 | result.parts.sign = sign;
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| 42 |
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| 43 | /* find first nonzero digit and shift result and detect possibly underflow */
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| 44 | while ((cexp > 0) && (cfrac) && (!(cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1 ) )))) {
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| 45 | cexp--;
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| 46 | cfrac <<= 1;
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| 47 | /* TODO: fix underflow */
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| 48 | };
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| 49 |
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| 50 | cfrac >>= 1;
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| 51 | ++cexp;
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| 52 | cfrac += (0x1 << (64 - FLOAT64_FRACTION_SIZE - 3));
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| 53 |
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| 54 | if (cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1 ))) {
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| 55 | ++cexp;
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| 56 | cfrac >>= 1;
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| 57 | }
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| 58 |
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| 59 | /* check overflow */
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| 60 | if (cexp >= FLOAT64_MAX_EXPONENT ) {
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| 61 | /* FIXME: overflow, return infinity */
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| 62 | result.parts.exp = FLOAT64_MAX_EXPONENT;
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| 63 | result.parts.fraction = 0;
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| 64 | return result;
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| 65 | }
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| 66 |
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| 67 | if (cexp < 0) {
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| 68 | /* FIXME: underflow */
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| 69 | result.parts.exp = 0;
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| 70 | if ((cexp + FLOAT64_FRACTION_SIZE) < 0) {
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| 71 | result.parts.fraction = 0;
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| 72 | return result;
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| 73 | }
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| 74 | cfrac >>= 1;
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| 75 | while (cexp < 0) {
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| 76 | cexp ++;
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| 77 | cfrac >>= 1;
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| 78 | }
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| 79 | return result;
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| 80 |
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| 81 | } else {
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| 82 | cexp ++; /*normalized*/
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| 83 | result.parts.exp = (__u32)cexp;
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| 84 | }
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| 85 |
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| 86 | result.parts.fraction = ((cfrac >>(64 - FLOAT64_FRACTION_SIZE - 2 ) ) & (~FLOAT64_HIDDEN_BIT_MASK));
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| 87 |
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| 88 | return result;
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| 89 | }
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