diff options
Diffstat (limited to 'sysdeps/powerpc/fpu/round_to_integer.h')
| -rw-r--r-- | sysdeps/powerpc/fpu/round_to_integer.h | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/sysdeps/powerpc/fpu/round_to_integer.h b/sysdeps/powerpc/fpu/round_to_integer.h index ff77dde394..b318e37190 100644 --- a/sysdeps/powerpc/fpu/round_to_integer.h +++ b/sysdeps/powerpc/fpu/round_to_integer.h @@ -24,7 +24,8 @@ enum round_mode { CEIL, - FLOOR + FLOOR, + ROUND }; static inline void @@ -35,6 +36,7 @@ set_fenv_mode (enum round_mode mode) { case CEIL: rmode = FE_UPWARD; break; case FLOOR: rmode = FE_DOWNWARD; break; + case ROUND: rmode = FE_TOWARDZERO; break; default: rmode = FE_TONEAREST; break; } __fesetround_inline_nocheck (rmode); @@ -57,12 +59,24 @@ round_to_integer_float (enum round_mode mode, float x) set_fenv_mode (mode); if (x > 0.0) { + /* IEEE 1003.1 round function. IEEE specifies "round to the nearest + integer value, rounding halfway cases away from zero, regardless of + the current rounding mode." However PowerPC Architecture defines + "Round to Nearest" as "Choose the best approximation. In case of a + tie, choose the one that is even (least significant bit o).". + So we can't use the PowerPC "Round to Nearest" mode. Instead we set + "Round toward Zero" mode and round by adding +-0.5 before rounding + to the integer value. */ + if (mode == ROUND) + r += 0.5f; r += 0x1p+23; r -= 0x1p+23; r = fabs (r); } else if (x < 0.0) { + if (mode == ROUND) + r -= 0.5f; r -= 0x1p+23; r += 0x1p+23; r = -fabs (r); @@ -89,12 +103,16 @@ round_to_integer_double (enum round_mode mode, double x) set_fenv_mode (mode); if (x > 0.0) { + if (mode == ROUND) + r += 0.5; r += 0x1p+52; r -= 0x1p+52; r = fabs (r); } else if (x < 0.0) { + if (mode == ROUND) + r -= 0.5; r -= 0x1p+52; r += 0x1p+52; r = -fabs (r); |