1/*
2 * Written by J.T. Conklin <jtc@netbsd.org>.
3 * Public domain.
4 * Adapted for float type by Ulrich Drepper <drepper@cygnus.com>.
5 *
6 * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
7 */
8
9#include <machine/asm.h>
10
11RCSID("$NetBSD: $")
12
13#ifdef __ELF__
14	.section .rodata
15#else
16	.text
17#endif
18	.align ALIGNARG(4)
19	ASM_TYPE_DIRECTIVE(one,@object)
20one:	.double 1.0
21	ASM_SIZE_DIRECTIVE(one)
22	/* It is not important that this constant is precise.  It is only
23	   a value which is known to be on the safe side for using the
24	   fyl2xp1 instruction.  */
25	ASM_TYPE_DIRECTIVE(limit,@object)
26limit:	.double 0.29
27	ASM_SIZE_DIRECTIVE(limit)
28
29
30#ifdef PIC
31#define MO(op) op##@GOTOFF(%edx)
32#else
33#define MO(op) op
34#endif
35
36	.text
37ENTRY(__ieee754_log10f)
38	fldlg2			// log10(2)
39	flds	4(%esp)		// x : log10(2)
40#ifdef PIC
41	call	1f
421:	popl	%edx
43	addl	$_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
44#endif
45	fxam
46	fnstsw
47	fld	%st		// x : x : log10(2)
48	sahf
49	jc	3f		// in case x is NaN or �Inf
504:	fsubl	MO(one)		// x-1 : x : log10(2)
51	fld	%st		// x-1 : x-1 : x : log10(2)
52	fabs			// |x-1| : x-1 : x : log10(2)
53	fcompl	MO(limit)	// x-1 : x : log10(2)
54	fnstsw			// x-1 : x : log10(2)
55	andb	$0x45, %ah
56	jz	2f
57	fstp	%st(1)		// x-1 : log10(2)
58	fyl2xp1			// log10(x)
59	ret
60
612:	fstp	%st(0)		// x : log10(2)
62	fyl2x			// log10(x)
63	ret
64
653:	jp	4b		// in case x is �Inf
66	fstp	%st(1)
67	fstp	%st(1)
68	ret
69END (__ieee754_log10f)
70