From 2fa96a801df7acbfdcb0103a9fcb6e54000bab0d Mon Sep 17 00:00:00 2001 From: marius Date: Sat, 20 Mar 2010 22:32:13 +0000 Subject: [PATCH] - While SPARC V9 allows tininess to be detected either before or after rounding (impl. dep. #55), the SPARC JPS1 responsible for SPARC64 and UltraSPARC processors defines that in all cases tinyness is detected before rounding, therefore rounding up to the smallest normalised number should set the underflow flag. - If an infinite result is rounded down, the result should have an exponent 1 less than the value for infinity. PR: 144900 Submitted by: Peter Jeremy MFC after: 3 days --- lib/libc/sparc64/fpu/fpu_implode.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/lib/libc/sparc64/fpu/fpu_implode.c b/lib/libc/sparc64/fpu/fpu_implode.c index 82a8460b5dde..2a2a9d0be744 100644 --- a/lib/libc/sparc64/fpu/fpu_implode.c +++ b/lib/libc/sparc64/fpu/fpu_implode.c @@ -329,8 +329,9 @@ __fpu_ftos(fe, fp) * right to introduce leading zeroes. Rounding then acts * differently for normals and subnormals: the largest subnormal * may round to the smallest normal (1.0 x 2^minexp), or may - * remain subnormal. In the latter case, signal an underflow - * if the result was inexact or if underflow traps are enabled. + * remain subnormal. A number that is subnormal before rounding + * will signal an underflow if the result is inexact or if underflow + * traps are enabled. * * Rounding a normal, on the other hand, always produces another * normal (although either way the result might be too big for @@ -345,8 +346,10 @@ __fpu_ftos(fe, fp) if ((exp = fp->fp_exp + SNG_EXP_BIAS) <= 0) { /* subnormal */ /* -NG for g,r; -SNG_FRACBITS-exp for fraction */ (void) __fpu_shr(fp, FP_NMANT - FP_NG - SNG_FRACBITS - exp); - if (fpround(fe, fp) && fp->fp_mant[3] == SNG_EXP(1)) + if (fpround(fe, fp) && fp->fp_mant[3] == SNG_EXP(1)) { + fe->fe_cx |= FSR_UF; return (sign | SNG_EXP(1) | 0); + } if ((fe->fe_cx & FSR_NX) || (fe->fe_fsr & (FSR_UF << FSR_TEM_SHIFT))) fe->fe_cx |= FSR_UF; @@ -407,6 +410,7 @@ zero: res[1] = 0; if ((exp = fp->fp_exp + DBL_EXP_BIAS) <= 0) { (void) __fpu_shr(fp, FP_NMANT - FP_NG - DBL_FRACBITS - exp); if (fpround(fe, fp) && fp->fp_mant[2] == DBL_EXP(1)) { + fe->fe_cx |= FSR_UF; res[1] = 0; return (sign | DBL_EXP(1) | 0); } @@ -426,7 +430,7 @@ zero: res[1] = 0; return (sign | DBL_EXP(DBL_EXP_INFNAN) | 0); } res[1] = ~0; - return (sign | DBL_EXP(DBL_EXP_INFNAN) | DBL_MASK); + return (sign | DBL_EXP(DBL_EXP_INFNAN - 1) | DBL_MASK); } done: res[1] = fp->fp_mant[3]; @@ -468,6 +472,7 @@ zero: res[1] = res[2] = res[3] = 0; if ((exp = fp->fp_exp + EXT_EXP_BIAS) <= 0) { (void) __fpu_shr(fp, FP_NMANT - FP_NG - EXT_FRACBITS - exp); if (fpround(fe, fp) && fp->fp_mant[0] == EXT_EXP(1)) { + fe->fe_cx |= FSR_UF; res[1] = res[2] = res[3] = 0; return (sign | EXT_EXP(1) | 0); } @@ -487,7 +492,7 @@ zero: res[1] = res[2] = res[3] = 0; return (sign | EXT_EXP(EXT_EXP_INFNAN) | 0); } res[1] = res[2] = res[3] = ~0; - return (sign | EXT_EXP(EXT_EXP_INFNAN) | EXT_MASK); + return (sign | EXT_EXP(EXT_EXP_INFNAN - 1) | EXT_MASK); } done: res[1] = fp->fp_mant[1];