10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 */
25 /*
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 #if defined(ELFOBJ)
31 #pragma weak logbf = __logbf
32 #endif
33
34 #include "libm.h"
35 #include "xpg6.h" /* __xpg6 */
36 #define _C99SUSv3_logb _C99SUSv3_logb_subnormal_is_like_ilogb
37
38 #if defined(USE_FPSCALE) || defined(__x86)
39 static const float two25 = 33554432.0F;
40 #else
41 /*
42 * v: a non-zero subnormal |x|
43 */
44 static int
45 ilogbf_subnormal(unsigned v) {
46 int r = -126 - 23;
47
48 if (v & 0xffff0000)
49 r += 16, v >>= 16;
50 if (v & 0xff00)
51 r += 8, v >>= 8;
52 if (v & 0xf0)
53 r += 4, v >>= 4;
54 v <<= 1;
55 return (r + ((0xffffaa50 >> v) & 0x3));
56 }
57 #endif /* defined(USE_FPSCALE) */
58
59 static float
60 raise_division(float t) {
61 #pragma STDC FENV_ACCESS ON
62 static const float zero = 0.0F;
63 return (t / zero);
64 }
65
66 float
67 logbf(float x) {
68 int k = *((int *) &x) & ~0x80000000;
69
70 if (k < 0x00800000) {
71 if (k == 0)
72 return (raise_division(-1.0F));
73 else if ((__xpg6 & _C99SUSv3_logb) != 0) {
74 #if defined(USE_FPSCALE) || defined(__x86)
75 x *= two25;
76 return ((float) (((*((int *) &x) & 0x7f800000) >> 23) -
77 152));
78 #else
79 return ((float) ilogbf_subnormal(k));
80 #endif
81 } else
82 return (-126.F);
83 } else if (k < 0x7f800000)
84 return ((float) ((k >> 23) - 127));
85 else
86 return (x * x);
87 }
|
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 */
25 /*
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 #pragma weak __logbf = logbf
31
32 #include "libm.h"
33 #include "xpg6.h" /* __xpg6 */
34 #define _C99SUSv3_logb _C99SUSv3_logb_subnormal_is_like_ilogb
35
36 #if defined(__x86)
37 static const float two25 = 33554432.0F;
38 #else
39 /*
40 * v: a non-zero subnormal |x|
41 */
42 static int
43 ilogbf_subnormal(unsigned v) {
44 int r = -126 - 23;
45
46 if (v & 0xffff0000)
47 r += 16, v >>= 16;
48 if (v & 0xff00)
49 r += 8, v >>= 8;
50 if (v & 0xf0)
51 r += 4, v >>= 4;
52 v <<= 1;
53 return (r + ((0xffffaa50 >> v) & 0x3));
54 }
55 #endif /* defined(__x86) */
56
57 static float
58 raise_division(float t) {
59 #pragma STDC FENV_ACCESS ON
60 static const float zero = 0.0F;
61 return (t / zero);
62 }
63
64 float
65 logbf(float x) {
66 int k = *((int *) &x) & ~0x80000000;
67
68 if (k < 0x00800000) {
69 if (k == 0)
70 return (raise_division(-1.0F));
71 else if ((__xpg6 & _C99SUSv3_logb) != 0) {
72 #if defined(__x86)
73 x *= two25;
74 return ((float) (((*((int *) &x) & 0x7f800000) >> 23) -
75 152));
76 #else
77 return ((float) ilogbf_subnormal(k));
78 #endif
79 } else
80 return (-126.F);
81 } else if (k < 0x7f800000)
82 return ((float) ((k >> 23) - 127));
83 else
84 return (x * x);
85 }
|