1 | /* |
2 | * Written by J.T. Conklin <jtc@netbsd.org>. |
3 | * Changes for long double by Ulrich Drepper <drepper@cygnus.com> |
4 | * Adapted for x86-64 by Andreas Jaeger <aj@suse.de>. |
5 | * Public domain. |
6 | */ |
7 | |
8 | #include <machine/asm.h> |
9 | |
10 | ENTRY(__ieee754_ilogbl) |
11 | fldt 8(%rsp) |
12 | /* I added the following ugly construct because ilogb(+-Inf) is |
13 | required to return INT_MAX in ISO C99. |
14 | -- jakub@redhat.com. */ |
15 | fxam /* Is NaN or +-Inf? */ |
16 | fstsw %ax |
17 | movb $0x45, %dh |
18 | andb %ah, %dh |
19 | cmpb $0x05, %dh |
20 | je 1f /* Is +-Inf, jump. */ |
21 | cmpb $0x40, %dh |
22 | je 2f /* Is +-Inf, jump. */ |
23 | |
24 | fxtract |
25 | fstp %st |
26 | |
27 | fistpl -4(%rsp) |
28 | fwait |
29 | movl -4(%rsp),%eax |
30 | |
31 | ret |
32 | |
33 | 1: fstp %st |
34 | movl $0x7fffffff, %eax |
35 | ret |
36 | 2: fstp %st |
37 | movl $0x80000000, %eax /* FP_ILOGB0 */ |
38 | ret |
39 | END (__ieee754_ilogbl) |
40 | |