WebSVN – HelenOS – Diff – /trunk/uspace/softfloat/generic/sub.c


/*
 * 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;
}
 
 
 /** @}
 */
 
 

Rev 1787	Rev 2071
1	/*	1	/*
2	* Copyright (C) 2005 Josef Cejka	2	* Copyright (c) 2005 Josef Cejka
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup softfloat	29	/** @addtogroup softfloat
30	* @{	30	* @{
31	*/	31	*/
32	/** @file	32	/** @file
33	*/	33	*/
34		34
35	#include<sftypes.h>	35	#include<sftypes.h>
36	#include<sub.h>	36	#include<sub.h>
37	#include<comparison.h>	37	#include<comparison.h>
38		38
39	/** Subtract two float32 numbers with same signs	39	/** Subtract two float32 numbers with same signs
40	*/	40	*/
41	float32 subFloat32(float32 a, float32 b)	41	float32 subFloat32(float32 a, float32 b)
42	{	42	{
43	int expdiff;	43	int expdiff;
44	uint32_t exp1, exp2, frac1, frac2;	44	uint32_t exp1, exp2, frac1, frac2;
45	float32 result;	45	float32 result;
46		46
47	result.f = 0;	47	result.f = 0;
48		48
49	expdiff = a.parts.exp - b.parts.exp;	49	expdiff = a.parts.exp - b.parts.exp;
50	if ((expdiff < 0 ) \|\| ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) {	50	if ((expdiff < 0 ) \|\| ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) {
51	if (isFloat32NaN(b)) {	51	if (isFloat32NaN(b)) {
52	/* TODO: fix SigNaN */	52	/* TODO: fix SigNaN */
53	if (isFloat32SigNaN(b)) {	53	if (isFloat32SigNaN(b)) {
54	};	54	};
55	return b;	55	return b;
56	};	56	};
57		57
58	if (b.parts.exp == FLOAT32_MAX_EXPONENT) {	58	if (b.parts.exp == FLOAT32_MAX_EXPONENT) {
59	b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */	59	b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */
60	return b;	60	return b;
61	}	61	}
62		62
63	result.parts.sign = !a.parts.sign;	63	result.parts.sign = !a.parts.sign;
64		64
65	frac1 = b.parts.fraction;	65	frac1 = b.parts.fraction;
66	exp1 = b.parts.exp;	66	exp1 = b.parts.exp;
67	frac2 = a.parts.fraction;	67	frac2 = a.parts.fraction;
68	exp2 = a.parts.exp;	68	exp2 = a.parts.exp;
69	expdiff *= -1;	69	expdiff *= -1;
70	} else {	70	} else {
71	if (isFloat32NaN(a)) {	71	if (isFloat32NaN(a)) {
72	/* TODO: fix SigNaN */	72	/* TODO: fix SigNaN */
73	if (isFloat32SigNaN(a) \|\| isFloat32SigNaN(b)) {	73	if (isFloat32SigNaN(a) \|\| isFloat32SigNaN(b)) {
74	};	74	};
75	return a;	75	return a;
76	};	76	};
77		77
78	if (a.parts.exp == FLOAT32_MAX_EXPONENT) {	78	if (a.parts.exp == FLOAT32_MAX_EXPONENT) {
79	if (b.parts.exp == FLOAT32_MAX_EXPONENT) {	79	if (b.parts.exp == FLOAT32_MAX_EXPONENT) {
80	/* inf - inf => nan */	80	/* inf - inf => nan */
81	/* TODO: fix exception */	81	/* TODO: fix exception */
82	result.binary = FLOAT32_NAN;	82	result.binary = FLOAT32_NAN;
83	return result;	83	return result;
84	};	84	};
85	return a;	85	return a;
86	}	86	}
87		87
88	result.parts.sign = a.parts.sign;	88	result.parts.sign = a.parts.sign;
89		89
90	frac1 = a.parts.fraction;	90	frac1 = a.parts.fraction;
91	exp1 = a.parts.exp;	91	exp1 = a.parts.exp;
92	frac2 = b.parts.fraction;	92	frac2 = b.parts.fraction;
93	exp2 = b.parts.exp;	93	exp2 = b.parts.exp;
94	};	94	};
95		95
96	if (exp1 == 0) {	96	if (exp1 == 0) {
97	/* both are denormalized */	97	/* both are denormalized */
98	result.parts.fraction = frac1-frac2;	98	result.parts.fraction = frac1-frac2;
99	if (result.parts.fraction > frac1) {	99	if (result.parts.fraction > frac1) {
100	/* TODO: underflow exception */	100	/* TODO: underflow exception */
101	return result;	101	return result;
102	};	102	};
103	result.parts.exp = 0;	103	result.parts.exp = 0;
104	return result;	104	return result;
105	};	105	};
106		106
107	/* add hidden bit */	107	/* add hidden bit */
108	frac1 \|= FLOAT32_HIDDEN_BIT_MASK;	108	frac1 \|= FLOAT32_HIDDEN_BIT_MASK;
109		109
110	if (exp2 == 0) {	110	if (exp2 == 0) {
111	/* denormalized */	111	/* denormalized */
112	--expdiff;	112	--expdiff;
113	} else {	113	} else {
114	/* normalized */	114	/* normalized */
115	frac2 \|= FLOAT32_HIDDEN_BIT_MASK;	115	frac2 \|= FLOAT32_HIDDEN_BIT_MASK;
116	};	116	};
117		117
118	/* create some space for rounding */	118	/* create some space for rounding */
119	frac1 <<= 6;	119	frac1 <<= 6;
120	frac2 <<= 6;	120	frac2 <<= 6;
121		121
122	if (expdiff > FLOAT32_FRACTION_SIZE + 1) {	122	if (expdiff > FLOAT32_FRACTION_SIZE + 1) {
123	goto done;	123	goto done;
124	};	124	};
125		125
126	frac1 = frac1 - (frac2 >> expdiff);	126	frac1 = frac1 - (frac2 >> expdiff);
127	done:	127	done:
128	/* TODO: find first nonzero digit and shift result and detect possibly underflow */	128	/* TODO: find first nonzero digit and shift result and detect possibly underflow */
129	while ((exp1 > 0) && (!(frac1 & (FLOAT32_HIDDEN_BIT_MASK << 6 )))) {	129	while ((exp1 > 0) && (!(frac1 & (FLOAT32_HIDDEN_BIT_MASK << 6 )))) {
130	--exp1;	130	--exp1;
131	frac1 <<= 1;	131	frac1 <<= 1;
132	/* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */	132	/* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */
133	};	133	};
134		134
135	/* rounding - if first bit after fraction is set then round up */	135	/* rounding - if first bit after fraction is set then round up */
136	frac1 += 0x20;	136	frac1 += 0x20;
137		137
138	if (frac1 & (FLOAT32_HIDDEN_BIT_MASK << 7)) {	138	if (frac1 & (FLOAT32_HIDDEN_BIT_MASK << 7)) {
139	++exp1;	139	++exp1;
140	frac1 >>= 1;	140	frac1 >>= 1;
141	};	141	};
142		142
143	/Clear hidden bit and shift /	143	/Clear hidden bit and shift /
144	result.parts.fraction = ((frac1 >> 6) & (~FLOAT32_HIDDEN_BIT_MASK));	144	result.parts.fraction = ((frac1 >> 6) & (~FLOAT32_HIDDEN_BIT_MASK));
145	result.parts.exp = exp1;	145	result.parts.exp = exp1;
146		146
147	return result;	147	return result;
148	}	148	}
149		149
150	/** Subtract two float64 numbers with same signs	150	/** Subtract two float64 numbers with same signs
151	*/	151	*/
152	float64 subFloat64(float64 a, float64 b)	152	float64 subFloat64(float64 a, float64 b)
153	{	153	{
154	int expdiff;	154	int expdiff;
155	uint32_t exp1, exp2;	155	uint32_t exp1, exp2;
156	uint64_t frac1, frac2;	156	uint64_t frac1, frac2;
157	float64 result;	157	float64 result;
158		158
159	result.d = 0;	159	result.d = 0;
160		160
161	expdiff = a.parts.exp - b.parts.exp;	161	expdiff = a.parts.exp - b.parts.exp;
162	if ((expdiff < 0 ) \|\| ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) {	162	if ((expdiff < 0 ) \|\| ((expdiff == 0) && (a.parts.fraction < b.parts.fraction))) {
163	if (isFloat64NaN(b)) {	163	if (isFloat64NaN(b)) {
164	/* TODO: fix SigNaN */	164	/* TODO: fix SigNaN */
165	if (isFloat64SigNaN(b)) {	165	if (isFloat64SigNaN(b)) {
166	};	166	};
167	return b;	167	return b;
168	};	168	};
169		169
170	if (b.parts.exp == FLOAT64_MAX_EXPONENT) {	170	if (b.parts.exp == FLOAT64_MAX_EXPONENT) {
171	b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */	171	b.parts.sign = !b.parts.sign; /* num -(+-inf) = -+inf */
172	return b;	172	return b;
173	}	173	}
174		174
175	result.parts.sign = !a.parts.sign;	175	result.parts.sign = !a.parts.sign;
176		176
177	frac1 = b.parts.fraction;	177	frac1 = b.parts.fraction;
178	exp1 = b.parts.exp;	178	exp1 = b.parts.exp;
179	frac2 = a.parts.fraction;	179	frac2 = a.parts.fraction;
180	exp2 = a.parts.exp;	180	exp2 = a.parts.exp;
181	expdiff *= -1;	181	expdiff *= -1;
182	} else {	182	} else {
183	if (isFloat64NaN(a)) {	183	if (isFloat64NaN(a)) {
184	/* TODO: fix SigNaN */	184	/* TODO: fix SigNaN */
185	if (isFloat64SigNaN(a) \|\| isFloat64SigNaN(b)) {	185	if (isFloat64SigNaN(a) \|\| isFloat64SigNaN(b)) {
186	};	186	};
187	return a;	187	return a;
188	};	188	};
189		189
190	if (a.parts.exp == FLOAT64_MAX_EXPONENT) {	190	if (a.parts.exp == FLOAT64_MAX_EXPONENT) {
191	if (b.parts.exp == FLOAT64_MAX_EXPONENT) {	191	if (b.parts.exp == FLOAT64_MAX_EXPONENT) {
192	/* inf - inf => nan */	192	/* inf - inf => nan */
193	/* TODO: fix exception */	193	/* TODO: fix exception */
194	result.binary = FLOAT64_NAN;	194	result.binary = FLOAT64_NAN;
195	return result;	195	return result;
196	};	196	};
197	return a;	197	return a;
198	}	198	}
199		199
200	result.parts.sign = a.parts.sign;	200	result.parts.sign = a.parts.sign;
201		201
202	frac1 = a.parts.fraction;	202	frac1 = a.parts.fraction;
203	exp1 = a.parts.exp;	203	exp1 = a.parts.exp;
204	frac2 = b.parts.fraction;	204	frac2 = b.parts.fraction;
205	exp2 = b.parts.exp;	205	exp2 = b.parts.exp;
206	};	206	};
207		207
208	if (exp1 == 0) {	208	if (exp1 == 0) {
209	/* both are denormalized */	209	/* both are denormalized */
210	result.parts.fraction = frac1 - frac2;	210	result.parts.fraction = frac1 - frac2;
211	if (result.parts.fraction > frac1) {	211	if (result.parts.fraction > frac1) {
212	/* TODO: underflow exception */	212	/* TODO: underflow exception */
213	return result;	213	return result;
214	};	214	};
215	result.parts.exp = 0;	215	result.parts.exp = 0;
216	return result;	216	return result;
217	};	217	};
218		218
219	/* add hidden bit */	219	/* add hidden bit */
220	frac1 \|= FLOAT64_HIDDEN_BIT_MASK;	220	frac1 \|= FLOAT64_HIDDEN_BIT_MASK;
221		221
222	if (exp2 == 0) {	222	if (exp2 == 0) {
223	/* denormalized */	223	/* denormalized */
224	--expdiff;	224	--expdiff;
225	} else {	225	} else {
226	/* normalized */	226	/* normalized */
227	frac2 \|= FLOAT64_HIDDEN_BIT_MASK;	227	frac2 \|= FLOAT64_HIDDEN_BIT_MASK;
228	};	228	};
229		229
230	/* create some space for rounding */	230	/* create some space for rounding */
231	frac1 <<= 6;	231	frac1 <<= 6;
232	frac2 <<= 6;	232	frac2 <<= 6;
233		233
234	if (expdiff > FLOAT64_FRACTION_SIZE + 1) {	234	if (expdiff > FLOAT64_FRACTION_SIZE + 1) {
235	goto done;	235	goto done;
236	};	236	};
237		237
238	frac1 = frac1 - (frac2 >> expdiff);	238	frac1 = frac1 - (frac2 >> expdiff);
239	done:	239	done:
240	/* TODO: find first nonzero digit and shift result and detect possibly underflow */	240	/* TODO: find first nonzero digit and shift result and detect possibly underflow */
241	while ((exp1 > 0) && (!(frac1 & (FLOAT64_HIDDEN_BIT_MASK << 6 )))) {	241	while ((exp1 > 0) && (!(frac1 & (FLOAT64_HIDDEN_BIT_MASK << 6 )))) {
242	--exp1;	242	--exp1;
243	frac1 <<= 1;	243	frac1 <<= 1;
244	/* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */	244	/* TODO: fix underflow - frac1 == 0 does not necessary means underflow... */
245	};	245	};
246		246
247	/* rounding - if first bit after fraction is set then round up */	247	/* rounding - if first bit after fraction is set then round up */
248	frac1 += 0x20;	248	frac1 += 0x20;
249		249
250	if (frac1 & (FLOAT64_HIDDEN_BIT_MASK << 7)) {	250	if (frac1 & (FLOAT64_HIDDEN_BIT_MASK << 7)) {
251	++exp1;	251	++exp1;
252	frac1 >>= 1;	252	frac1 >>= 1;
253	};	253	};
254		254
255	/Clear hidden bit and shift /	255	/Clear hidden bit and shift /
256	result.parts.fraction = ((frac1 >> 6) & (~FLOAT64_HIDDEN_BIT_MASK));	256	result.parts.fraction = ((frac1 >> 6) & (~FLOAT64_HIDDEN_BIT_MASK));
257	result.parts.exp = exp1;	257	result.parts.exp = exp1;
258		258
259	return result;	259	return result;
260	}	260	}
261		261
262		262
263	/** @}	263	/** @}
264	*/	264	*/
265		265
266		266

Subversion Repositories HelenOS

(root)/trunk/uspace/softfloat/generic/sub.c – Rev 1787 → 2071