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 |
}; |
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/** 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; |
} |
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/** 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; |
} |
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/** 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; |
} |
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/** 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; |
} |
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/** @} |
*/ |
|