src/compiler-rt/lib/builtins/i386/floatdidf.S

   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 CONST_SECTION
  11
  12         .balign 16
  13 twop52:
  14         .quad 0x4330000000000000
  15
  16         .balign 16
  17 twop32:
  18         .quad 0x41f0000000000000
  19
  20 #define REL_ADDR(_a)    (_a)-0b(%eax)
  21
  22 .text
  23 .balign 4
  24 DEFINE_COMPILERRT_FUNCTION(__floatdidf)
  25         cvtsi2sd        8(%esp),                        %xmm1
  26         movss           4(%esp),                        %xmm0 // low 32 bits of a
  27         calll           0f
  28 0:      popl            %eax
  29         mulsd           REL_ADDR(twop32),       %xmm1 // a_hi as a double (without rounding)
  30         movsd           REL_ADDR(twop52),       %xmm2 // 0x1.0p52
  31         subsd           %xmm2,                          %xmm1 // a_hi - 0x1p52 (no rounding occurs)
  32         orpd            %xmm2,                          %xmm0 // 0x1p52 + a_lo (no rounding occurs)
  33         addsd           %xmm1,                          %xmm0 // a_hi + a_lo   (round happens here)
  34         movsd           %xmm0,                     4(%esp)
  35         fldl       4(%esp)
  36         ret
  37 END_COMPILERRT_FUNCTION(__floatdidf)
  38
  39 #endif // __i386__