s_exp2f.c (86c2e0c047d762127e31ac7510188ba436d299f3) s_exp2f.c (684217d8896437b642fa8a6020bb5318b2c330ed)
1/*-
2 * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright

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22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
1/*-
2 * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright

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22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <float.h>
31
30#include "math.h"
31#include "math_private.h"
32
33#define TBLBITS 4
34#define TBLSIZE (1 << TBLBITS)
35
36static const float
37 huge = 0x1p100f,

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86 *
87 * Tang, P. Table-driven Implementation of the Exponential Function
88 * in IEEE Floating-Point Arithmetic. TOMS 15(2), 144-157 (1989).
89 */
90float
91exp2f(float x)
92{
93 double tv;
32#include "math.h"
33#include "math_private.h"
34
35#define TBLBITS 4
36#define TBLSIZE (1 << TBLBITS)
37
38static const float
39 huge = 0x1p100f,

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88 *
89 * Tang, P. Table-driven Implementation of the Exponential Function
90 * in IEEE Floating-Point Arithmetic. TOMS 15(2), 144-157 (1989).
91 */
92float
93exp2f(float x)
94{
95 double tv;
94 float r, z;
95 volatile float t; /* prevent gcc from using too much precision */
96 float r, t, z;
96 uint32_t hx, hr, ix, i0;
97 int32_t k;
98
99 /* Filter out exceptional cases. */
100 GET_FLOAT_WORD(hx,x);
101 ix = hx & 0x7fffffff; /* high word of |x| */
102 if(ix >= 0x43000000) { /* |x| >= 128 */
103 if(ix >= 0x7f800000) {

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110 return (huge * huge); /* overflow */
111 if(x <= -0x1.2cp7f)
112 return (twom100 * twom100); /* underflow */
113 } else if (ix <= 0x33000000) { /* |x| <= 0x1p-25 */
114 return (1.0f + x);
115 }
116
117 /* Reduce x, computing z, i0, and k. */
97 uint32_t hx, hr, ix, i0;
98 int32_t k;
99
100 /* Filter out exceptional cases. */
101 GET_FLOAT_WORD(hx,x);
102 ix = hx & 0x7fffffff; /* high word of |x| */
103 if(ix >= 0x43000000) { /* |x| >= 128 */
104 if(ix >= 0x7f800000) {

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111 return (huge * huge); /* overflow */
112 if(x <= -0x1.2cp7f)
113 return (twom100 * twom100); /* underflow */
114 } else if (ix <= 0x33000000) { /* |x| <= 0x1p-25 */
115 return (1.0f + x);
116 }
117
118 /* Reduce x, computing z, i0, and k. */
118 t = x + redux;
119 STRICT_ASSIGN(float, t, x + redux);
119 GET_FLOAT_WORD(i0, t);
120 i0 += TBLSIZE / 2;
121 k = (i0 >> TBLBITS) << 23;
122 i0 &= TBLSIZE - 1;
123 t -= redux;
124 z = x - t;
125
126 /* Compute r = exp2(y) = exp2ft[i0] * p(z). */

--- 16 unchanged lines hidden --- 		120 GET_FLOAT_WORD(i0, t);
121 i0 += TBLSIZE / 2;
122 k = (i0 >> TBLBITS) << 23;
123 i0 &= TBLSIZE - 1;
124 t -= redux;
125 z = x - t;
126
127 /* Compute r = exp2(y) = exp2ft[i0] * p(z). */

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