diff options
Diffstat (limited to 'libm/powerpc/classic/s_trunc.c')
-rw-r--r-- | libm/powerpc/classic/s_trunc.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/libm/powerpc/classic/s_trunc.c b/libm/powerpc/classic/s_trunc.c new file mode 100644 index 000000000..f793992a7 --- /dev/null +++ b/libm/powerpc/classic/s_trunc.c @@ -0,0 +1,89 @@ +#include <limits.h> +#include <math.h> +#include <endian.h> + +typedef union + { + struct { +#if (__BYTE_ORDER == __BIG_ENDIAN) + unsigned long int hi; + unsigned long int lo; +#else + unsigned long int lo; + unsigned long int hi; +#endif + } words; + double dbl; + } DblInHex; + +static const unsigned long int signMask = 0x80000000ul; +static const double twoTo52 = 4503599627370496.0; + +/******************************************************************************* +* * +* The function trunc truncates its double argument to integral value * +* and returns the result in double format. This function signals * +* inexact if an ordered return value is not equal to the operand. * +* * +*******************************************************************************/ + +libm_hidden_proto(trunc) +double trunc ( double x ) + { + DblInHex argument,OldEnvironment; + register double y; + register unsigned long int xhi; + register long int target; + + argument.dbl = x; + xhi = argument.words.hi & 0x7fffffffUL; // xhi <- high half of |x| + target = ( argument.words.hi < signMask ); // flag positive sign + + if ( xhi < 0x43300000ul ) +/******************************************************************************* +* Is |x| < 2.0^53? * +*******************************************************************************/ + { + if ( xhi < 0x3ff00000ul ) +/******************************************************************************* +* Is |x| < 1.0? * +*******************************************************************************/ + { + if ( ( xhi | argument.words.lo ) != 0ul ) + { // raise deserved INEXACT + asm ("mffs %0" : "=f" (OldEnvironment.dbl)); + OldEnvironment.words.lo |= 0x02000000ul; + asm ("mtfsf 255,%0" : /*NULLOUT*/ : /*IN*/ "f" ( OldEnvironment.dbl )); + } + if ( target ) // return properly signed zero + return ( 0.0 ); + else + return ( -0.0 ); + } +/******************************************************************************* +* Is 1.0 < |x| < 2.0^52? * +*******************************************************************************/ + if ( target ) + { + y = ( x + twoTo52 ) - twoTo52; // round at binary point + if ( y > x ) + return ( y - 1.0 ); + else + return ( y ); + } + + else + { + y = ( x - twoTo52 ) + twoTo52; // round at binary point. + if ( y < x ) + return ( y + 1.0 ); + else + return ( y ); + } + } +/******************************************************************************* +* Is |x| >= 2.0^52 or x is a NaN. * +*******************************************************************************/ + return ( x ); + } +libm_hidden_def(trunc) |