floatdidf.S revision 9ad441ffec97db647fee3725b3424284fb913e14 
1// This file is dual licensed under the MIT and the University of Illinois Open
2// Source Licenses. See LICENSE.TXT for details.
3
4#include "../assembly.h"
5
6// double __floatundidf(du_int a);
7
8#ifdef __i386__
9
10#ifndef __ELF__
11.const
12#endif
13.align 4
14twop52: .quad 0x4330000000000000
15twop32: .quad 0x41f0000000000000
16
17#define REL_ADDR(_a)	(_a)-0b(%eax)
18
19.text
20.align 4
21DEFINE_COMPILERRT_FUNCTION(__floatdidf)
22	cvtsi2sd	8(%esp),			%xmm1
23	movss		4(%esp),			%xmm0 // low 32 bits of a
24	calll		0f
250:	popl		%eax
26	mulsd		REL_ADDR(twop32),	%xmm1 // a_hi as a double (without rounding)
27	movsd		REL_ADDR(twop52),	%xmm2 // 0x1.0p52
28	subsd		%xmm2,				%xmm1 // a_hi - 0x1p52 (no rounding occurs)
29	orpd		%xmm2,				%xmm0 // 0x1p52 + a_lo (no rounding occurs)
30	addsd		%xmm1,				%xmm0 // a_hi + a_lo   (round happens here)
31	movsd		%xmm0,			   4(%esp)
32	fldl	   4(%esp)
33	ret
34
35#endif // __i386__
36