| 0,0 → 1,265 |
|---|
| /* |
| * 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<sub.h> |
| #include<comparison.h> |
| |
| /** Subtract two float32 numbers with same signs |
| */ |
| float32 subFloat32(float32 a, float32 b) |
| { |
| int expdiff; |
| uint32_t exp1, exp2, frac1, frac2; |
| float32 result; |
| |
| result.f = 0; |
| |
| expdiff = a.parts.exp - b.parts.exp; |
| if ((expdiff < 0 ) || ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) { |
| if (isFloat32NaN(b)) { |
| /* TODO: fix SigNaN */ |
| if (isFloat32SigNaN(b)) { |
| }; |
| return b; |
| }; |
| |
| if (b.parts.exp == FLOAT32_MAX_EXPONENT) { |
| b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */ |
| return b; |
| } |
| |
| result.parts.sign = !a.parts.sign; |
| |
| frac1 = b.parts.fraction; |
| exp1 = b.parts.exp; |
| frac2 = a.parts.fraction; |
| exp2 = a.parts.exp; |
| expdiff *= -1; |
| } else { |
| if (isFloat32NaN(a)) { |
| /* TODO: fix SigNaN */ |
| if (isFloat32SigNaN(a) || isFloat32SigNaN(b)) { |
| }; |
| return a; |
| }; |
| |
| if (a.parts.exp == FLOAT32_MAX_EXPONENT) { |
| if (b.parts.exp == FLOAT32_MAX_EXPONENT) { |
| /* inf - inf => nan */ |
| /* TODO: fix exception */ |
| result.binary = FLOAT32_NAN; |
| return result; |
| }; |
| return a; |
| } |
| |
| result.parts.sign = a.parts.sign; |
| |
| frac1 = a.parts.fraction; |
| exp1 = a.parts.exp; |
| frac2 = b.parts.fraction; |
| exp2 = b.parts.exp; |
| }; |
| |
| if (exp1 == 0) { |
| /* both are denormalized */ |
| result.parts.fraction = frac1-frac2; |
| if (result.parts.fraction > frac1) { |
| /* TODO: underflow exception */ |
| return result; |
| }; |
| result.parts.exp = 0; |
| return result; |
| }; |
| |
| /* add hidden bit */ |
| frac1 |= FLOAT32_HIDDEN_BIT_MASK; |
| |
| if (exp2 == 0) { |
| /* denormalized */ |
| --expdiff; |
| } else { |
| /* normalized */ |
| frac2 |= FLOAT32_HIDDEN_BIT_MASK; |
| }; |
| |
| /* create some space for rounding */ |
| frac1 <<= 6; |
| frac2 <<= 6; |
| |
| if (expdiff > FLOAT32_FRACTION_SIZE + 1) { |
| goto done; |
| }; |
| |
| frac1 = frac1 - (frac2 >> expdiff); |
| done: |
| /* TODO: find first nonzero digit and shift result and detect possibly underflow */ |
| while ((exp1 > 0) && (!(frac1 & (FLOAT32_HIDDEN_BIT_MASK << 6 )))) { |
| --exp1; |
| frac1 <<= 1; |
| /* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */ |
| }; |
| |
| /* rounding - if first bit after fraction is set then round up */ |
| frac1 += 0x20; |
| |
| if (frac1 & (FLOAT32_HIDDEN_BIT_MASK << 7)) { |
| ++exp1; |
| frac1 >>= 1; |
| }; |
| |
| /*Clear hidden bit and shift */ |
| result.parts.fraction = ((frac1 >> 6) & (~FLOAT32_HIDDEN_BIT_MASK)); |
| result.parts.exp = exp1; |
| |
| return result; |
| } |
| |
| /** Subtract two float64 numbers with same signs |
| */ |
| float64 subFloat64(float64 a, float64 b) |
| { |
| int expdiff; |
| uint32_t exp1, exp2; |
| uint64_t frac1, frac2; |
| float64 result; |
| |
| result.d = 0; |
| |
| expdiff = a.parts.exp - b.parts.exp; |
| if ((expdiff < 0 ) || ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) { |
| if (isFloat64NaN(b)) { |
| /* TODO: fix SigNaN */ |
| if (isFloat64SigNaN(b)) { |
| }; |
| return b; |
| }; |
| |
| if (b.parts.exp == FLOAT64_MAX_EXPONENT) { |
| b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */ |
| return b; |
| } |
| |
| result.parts.sign = !a.parts.sign; |
| |
| frac1 = b.parts.fraction; |
| exp1 = b.parts.exp; |
| frac2 = a.parts.fraction; |
| exp2 = a.parts.exp; |
| expdiff *= -1; |
| } else { |
| if (isFloat64NaN(a)) { |
| /* TODO: fix SigNaN */ |
| if (isFloat64SigNaN(a) || isFloat64SigNaN(b)) { |
| }; |
| return a; |
| }; |
| |
| if (a.parts.exp == FLOAT64_MAX_EXPONENT) { |
| if (b.parts.exp == FLOAT64_MAX_EXPONENT) { |
| /* inf - inf => nan */ |
| /* TODO: fix exception */ |
| result.binary = FLOAT64_NAN; |
| return result; |
| }; |
| return a; |
| } |
| |
| result.parts.sign = a.parts.sign; |
| |
| frac1 = a.parts.fraction; |
| exp1 = a.parts.exp; |
| frac2 = b.parts.fraction; |
| exp2 = b.parts.exp; |
| }; |
| |
| if (exp1 == 0) { |
| /* both are denormalized */ |
| result.parts.fraction = frac1 - frac2; |
| if (result.parts.fraction > frac1) { |
| /* TODO: underflow exception */ |
| return result; |
| }; |
| result.parts.exp = 0; |
| return result; |
| }; |
| |
| /* add hidden bit */ |
| frac1 |= FLOAT64_HIDDEN_BIT_MASK; |
| |
| if (exp2 == 0) { |
| /* denormalized */ |
| --expdiff; |
| } else { |
| /* normalized */ |
| frac2 |= FLOAT64_HIDDEN_BIT_MASK; |
| }; |
| |
| /* create some space for rounding */ |
| frac1 <<= 6; |
| frac2 <<= 6; |
| |
| if (expdiff > FLOAT64_FRACTION_SIZE + 1) { |
| goto done; |
| }; |
| |
| frac1 = frac1 - (frac2 >> expdiff); |
| done: |
| /* TODO: find first nonzero digit and shift result and detect possibly underflow */ |
| while ((exp1 > 0) && (!(frac1 & (FLOAT64_HIDDEN_BIT_MASK << 6 )))) { |
| --exp1; |
| frac1 <<= 1; |
| /* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */ |
| }; |
| |
| /* rounding - if first bit after fraction is set then round up */ |
| frac1 += 0x20; |
| |
| if (frac1 & (FLOAT64_HIDDEN_BIT_MASK << 7)) { |
| ++exp1; |
| frac1 >>= 1; |
| }; |
| |
| /*Clear hidden bit and shift */ |
| result.parts.fraction = ((frac1 >> 6) & (~FLOAT64_HIDDEN_BIT_MASK)); |
| result.parts.exp = exp1; |
| |
| return result; |
| } |
| |
| |
| /** @} |
| */ |
| |