1/*
2 * Written by J.T. Conklin <jtc@netbsd.org>.
3 * Public domain.
4 *
5 * Adapted for `long double' by Ulrich Drepper <drepper@cygnus.com>.
6 * Adapted for x86-64 by Andreas Jaeger <aj@suse.de>.
7 */
8
9#include <machine/asm.h>
10#include <libm-alias-finite.h>
11
12 .section .rodata.cst8,"aM",@progbits,8
13
14 .p2align 3
15 .type one,@object
16one: .double 1.0
17 ASM_SIZE_DIRECTIVE(one)
18 /* It is not important that this constant is precise. It is only
19 a value which is known to be on the safe side for using the
20 fyl2xp1 instruction. */
21 .type limit,@object
22limit: .double 0.29
23 ASM_SIZE_DIRECTIVE(limit)
24
25
26#ifdef PIC
27# define MO(op) op##(%rip)
28#else
29# define MO(op) op
30#endif
31
32 .text
33ENTRY(__ieee754_logl)
34 fldln2 // log(2)
35 fldt 8(%rsp) // x : log(2)
36 fxam
37 fnstsw
38 fld %st // x : x : log(2)
39 testb $1, %ah
40 jnz 3f // in case x is NaN or +-Inf
41 movzwl 8+8(%rsp), %eax
42 cmpl $0xc000, %eax
43 jae 6f // x <= -2, avoid overflow from -LDBL_MAX - 1.
444: fsubl MO(one) // x-1 : x : log(2)
456: fld %st // x-1 : x-1 : x : log(2)
46 fabs // |x-1| : x-1 : x : log(2)
47 fcompl MO(limit) // x-1 : x : log(2)
48 fnstsw // x-1 : x : log(2)
49 andb $0x45, %ah
50 jz 2f
51 fxam
52 fnstsw
53 andb $0x45, %ah
54 cmpb $0x40, %ah
55 jne 5f
56 fabs // log(1) is +0 in all rounding modes.
575: fstp %st(1) // x-1 : log(2)
58 fyl2xp1 // log(x)
59 ret
60
612: fstp %st(0) // x : log(2)
62 fyl2x // log(x)
63 ret
64
653: testb $4, %ah
66 jnz 4b // in case x is +-Inf
67 fstp %st(1)
68 fstp %st(1)
69 fadd %st(0)
70 ret
71END (__ieee754_logl)
72
73
74ENTRY(__logl_finite)
75 fldln2 // log(2)
76 fldt 8(%rsp) // x : log(2)
77 fld %st // x : x : log(2)
78 fsubl MO(one) // x-1 : x : log(2)
79 fld %st // x-1 : x-1 : x : log(2)
80 fabs // |x-1| : x-1 : x : log(2)
81 fcompl MO(limit) // x-1 : x : log(2)
82 fnstsw // x-1 : x : log(2)
83 andb $0x45, %ah
84 jz 2b
85 fxam
86 fnstsw
87 andb $0x45, %ah
88 cmpb $0x40, %ah
89 jne 7f
90 fabs // log(1) is +0 in all rounding modes.
917: fstp %st(1) // x-1 : log(2)
92 fyl2xp1 // log(x)
93 ret
94END (__logl_finite)
95libm_alias_finite (__logl_finite, __logl)
96