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fixunsdfsi.S:

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Embalm.  Rewrite to do things much the same as gcc-2: use fistpq for speed
and elegance, and mishandle overflow consistently.  __fixunsdfsi() is no
longer called by gcc.
This commit is contained in:
bde 1994-12-27 13:37:38 +00:00
parent ae18e55c2b
commit 6b4e986e75
1 changed files with 22 additions and 37 deletions
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59
lib/libc/i386/gen/fixunsdfsi.S
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@ -34,49 +34,34 @@
* SUCH DAMAGE.
*
* from: @(#)fixunsdfsi.s 5.1 12/17/90
* $Id: fixunsdfsi.S,v 1.1 1993/12/05 13:01:03 ats Exp $
* $Id: fixunsdfsi.S,v 1.1 1994/08/05 01:18:05 wollman Exp $
*/
#if defined(LIBC_SCCS)
.text
.asciz "$Id: fixunsdfsi.S,v 1.1 1993/12/05 13:01:03 ats Exp $"
#endif
#if defined(LIBC_SCCS) && !defined(lint)
.asciz "$Id: fixunsdfsi.S,v 1.1 1994/08/05 01:18:05 wollman Exp $"
#endif /* LIBC_SCCS and not lint */
#include "DEFS.h"
#include "SYS.h"
ENTRY(__fixunsdfsi)
fldl 4(%esp) /* argument double to accum stack */
frndint /* create integer */
#ifdef PIC
PIC_PROLOGUE
leal PIC_GOTOFF(fbiggestsigned),%eax
PIC_EPILOGUE
fcoml (%eax)
#else
fcoml PIC_GOTOFF(fbiggestsigned) /* bigger than biggest signed? */
#endif
fstsw %ax
sahf
jnb 1f
fistpl 4(%esp)
fldl 4(%esp)
fnstcw 4(%esp)
movl 4(%esp),%eax
orb $(3 << 2),%ah # change rounding mode bitfield to 3 (chop)
movl %eax,8(%esp)
fldcw 8(%esp)
subl $8,%esp
fistpq (%esp) # convert to 64 bit integer
popl %eax
popl %edx # discard top 32 bits
fldcw 4(%esp)
ret
1:
#ifdef PIC
PIC_PROLOGUE
leal PIC_GOTOFF(fbiggestsigned),%eax
PIC_EPILOGUE
fsubl (%eax)
#else
fsubl PIC_GOTOFF(fbiggestsigned) /* reduce for proper conversion */
#endif
fistpl 4(%esp) /* convert */
movl 4(%esp),%eax
orl $0x80000000,%eax /* restore bias */
PIC_EPILOGUE
ret
fbiggestsigned: .double 0r2147483648.0
/*
* XXX - we are sloppy about overflow, the same as gcc-2. Values too big
* for a 64-bit (signed) integer cause an overflow trap or are silently
* converted to 0 if the overflow trap is masked. The remaining values
* too big for a 32-bit (unsigned) integer are silently truncated to 32
* bits. Negative values are converted like negative ints (no overflow)
* if they fit in 32 bits.
*/