| 0,0 → 1,215 |
|---|
| /* |
| * Copyright (C) 2005 Josef Cejka |
| * 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 disclaimer. |
| * - 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. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. |
| */ |
| |
| /** @addtogroup softfloat |
| * @{ |
| */ |
| /** @file |
| */ |
| |
| #include<sftypes.h> |
| #include<common.h> |
| |
| /* Table for fast leading zeroes counting */ |
| char zeroTable[256] = { |
| 8, 7, 7, 6, 6, 6, 6, 4, 4, 4, 4, 4, 4, 4, 4, \ |
| 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, \ |
| 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, \ |
| 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, \ |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \ |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \ |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \ |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \ |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 |
| }; |
| |
| |
| |
| /** Take fraction shifted by 10 bits to left, round it, normalize it and detect exceptions |
| * @param cexp exponent with bias |
| * @param cfrac fraction shifted 10 places left with added hidden bit |
| * @param sign |
| * @return valied float64 |
| */ |
| float64 finishFloat64(int32_t cexp, uint64_t cfrac, char sign) |
| { |
| float64 result; |
| |
| result.parts.sign = sign; |
| |
| /* find first nonzero digit and shift result and detect possibly underflow */ |
| while ((cexp > 0) && (cfrac) && (!(cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1 ) )))) { |
| cexp--; |
| cfrac <<= 1; |
| /* TODO: fix underflow */ |
| }; |
| |
| if ((cexp < 0) || ( cexp == 0 && (!(cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1)))))) { |
| /* FIXME: underflow */ |
| result.parts.exp = 0; |
| if ((cexp + FLOAT64_FRACTION_SIZE + 1) < 0) { /* +1 is place for rounding */ |
| result.parts.fraction = 0; |
| return result; |
| } |
| |
| while (cexp < 0) { |
| cexp++; |
| cfrac >>= 1; |
| } |
| |
| cfrac += (0x1 << (64 - FLOAT64_FRACTION_SIZE - 3)); |
| |
| if (!(cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1)))) { |
| |
| result.parts.fraction = ((cfrac >>(64 - FLOAT64_FRACTION_SIZE - 2) ) & (~FLOAT64_HIDDEN_BIT_MASK)); |
| return result; |
| } |
| } else { |
| cfrac += (0x1 << (64 - FLOAT64_FRACTION_SIZE - 3)); |
| } |
| |
| ++cexp; |
| |
| if (cfrac & (FLOAT64_HIDDEN_BIT_MASK << (64 - FLOAT64_FRACTION_SIZE - 1 ))) { |
| ++cexp; |
| cfrac >>= 1; |
| } |
| |
| /* check overflow */ |
| if (cexp >= FLOAT64_MAX_EXPONENT ) { |
| /* FIXME: overflow, return infinity */ |
| result.parts.exp = FLOAT64_MAX_EXPONENT; |
| result.parts.fraction = 0; |
| return result; |
| } |
| |
| result.parts.exp = (uint32_t)cexp; |
| |
| result.parts.fraction = ((cfrac >>(64 - FLOAT64_FRACTION_SIZE - 2 ) ) & (~FLOAT64_HIDDEN_BIT_MASK)); |
| |
| return result; |
| } |
| |
| /** Counts leading zeroes in 64bit unsigned integer |
| * @param i |
| */ |
| int countZeroes64(uint64_t i) |
| { |
| int j; |
| for (j =0; j < 64; j += 8) { |
| if ( i & (0xFFll << (56 - j))) { |
| return (j + countZeroes8(i >> (56 - j))); |
| } |
| } |
| |
| return 64; |
| } |
| |
| /** Counts leading zeroes in 32bit unsigned integer |
| * @param i |
| */ |
| int countZeroes32(uint32_t i) |
| { |
| int j; |
| for (j =0; j < 32; j += 8) { |
| if ( i & (0xFF << (24 - j))) { |
| return (j + countZeroes8(i >> (24 - j))); |
| } |
| } |
| |
| return 32; |
| } |
| |
| /** Counts leading zeroes in byte |
| * @param i |
| */ |
| int countZeroes8(uint8_t i) |
| { |
| return zeroTable[i]; |
| } |
| |
| /** Round and normalize number expressed by exponent and fraction with first bit (equal to hidden bit) at 30. bit |
| * @param exp exponent |
| * @param fraction part with hidden bit shifted to 30. bit |
| */ |
| void roundFloat32(int32_t *exp, uint32_t *fraction) |
| { |
| /* rounding - if first bit after fraction is set then round up */ |
| (*fraction) += (0x1 << 6); |
| |
| if ((*fraction) & (FLOAT32_HIDDEN_BIT_MASK << 8)) { |
| /* rounding overflow */ |
| ++(*exp); |
| (*fraction) >>= 1; |
| }; |
| |
| if (((*exp) >= FLOAT32_MAX_EXPONENT ) || ((*exp) < 0)) { |
| /* overflow - set infinity as result */ |
| (*exp) = FLOAT32_MAX_EXPONENT; |
| (*fraction) = 0; |
| return; |
| } |
| |
| return; |
| } |
| |
| /** Round and normalize number expressed by exponent and fraction with first bit (equal to hidden bit) at 62. bit |
| * @param exp exponent |
| * @param fraction part with hidden bit shifted to 62. bit |
| */ |
| void roundFloat64(int32_t *exp, uint64_t *fraction) |
| { |
| /* rounding - if first bit after fraction is set then round up */ |
| (*fraction) += (0x1 << 9); |
| |
| if ((*fraction) & (FLOAT64_HIDDEN_BIT_MASK << 11)) { |
| /* rounding overflow */ |
| ++(*exp); |
| (*fraction) >>= 1; |
| }; |
| |
| if (((*exp) >= FLOAT64_MAX_EXPONENT ) || ((*exp) < 0)) { |
| /* overflow - set infinity as result */ |
| (*exp) = FLOAT64_MAX_EXPONENT; |
| (*fraction) = 0; |
| return; |
| } |
| |
| return; |
| } |
| |
| /** @} |
| */ |
| |