From patchwork Fri Mar 11 18:12:25 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 510 Return-Path: Delivered-To: unknown Received: from imap.gmail.com (74.125.159.109) by localhost6.localdomain6 with IMAP4-SSL; 08 Jun 2011 14:43:13 -0000 Delivered-To: patches@linaro.org Received: by 10.224.67.207 with SMTP id s15cs69387qai; Fri, 11 Mar 2011 10:12:30 -0800 (PST) Received: by 10.216.35.82 with SMTP id t60mr7517212wea.46.1299867149461; Fri, 11 Mar 2011 10:12:29 -0800 (PST) Received: from mnementh.archaic.org.uk (mnementh.archaic.org.uk [81.2.115.146]) by mx.google.com with ESMTPS id w80si8732358wew.4.2011.03.11.10.12.28 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 11 Mar 2011 10:12:29 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 81.2.115.146 as permitted sender) client-ip=81.2.115.146; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 81.2.115.146 as permitted sender) smtp.mail=pm215@archaic.org.uk Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.72) (envelope-from ) id 1Py6p9-0005kG-67; Fri, 11 Mar 2011 18:12:27 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Cc: patches@linaro.org Subject: [PATCH 6/7] softfloat: Add float*_min() and float*_max() functions Date: Fri, 11 Mar 2011 18:12:25 +0000 Message-Id: <1299867146-22049-7-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1299867146-22049-1-git-send-email-peter.maydell@linaro.org> References: <1299867146-22049-1-git-send-email-peter.maydell@linaro.org> Add min and max operations to softfloat. This allows us to implement propagation of NaNs and handling of negative zero correctly (unlike the approach of having target helper routines return one of the operands based on the result of a comparison op). Signed-off-by: Peter Maydell --- fpu/softfloat.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ fpu/softfloat.h | 4 ++++ 2 files changed, 53 insertions(+), 0 deletions(-) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 30b07e9..55f02ae 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -6052,6 +6052,55 @@ int float128_compare_quiet( float128 a, float128 b STATUS_PARAM ) return float128_compare_internal(a, b, 1 STATUS_VAR); } +/* min() and max() functions. These can't be implemented as + * 'compare and pick one input' because that would mishandle + * NaNs and +0 vs -0. + */ +#define MINMAX(s, nan_exp) \ +INLINE float ## s float ## s ## _minmax(float ## s a, float ## s b, \ + int ismin STATUS_PARAM ) \ +{ \ + flag aSign, bSign; \ + bits ## s av, bv; \ + a = float ## s ## _squash_input_denormal(a STATUS_VAR); \ + b = float ## s ## _squash_input_denormal(b STATUS_VAR); \ + if (float ## s ## _is_any_nan(a) || \ + float ## s ## _is_any_nan(b)) { \ + return propagateFloat ## s ## NaN(a, b STATUS_VAR); \ + } \ + aSign = extractFloat ## s ## Sign(a); \ + bSign = extractFloat ## s ## Sign(b); \ + av = float ## s ## _val(a); \ + bv = float ## s ## _val(b); \ + if (aSign != bSign) { \ + if (ismin) { \ + return aSign ? a : b; \ + } else { \ + return aSign ? b : a; \ + } \ + } else { \ + if (ismin) { \ + return (aSign ^ (av < bv)) ? a : b; \ + } else { \ + return (aSign ^ (av < bv)) ? b : a; \ + } \ + } \ +} \ + \ +float ## s float ## s ## _min(float ## s a, float ## s b STATUS_PARAM) \ +{ \ + return float ## s ## _minmax(a, b, 1 STATUS_VAR); \ +} \ + \ +float ## s float ## s ## _max(float ## s a, float ## s b STATUS_PARAM) \ +{ \ + return float ## s ## _minmax(a, b, 0 STATUS_VAR); \ +} + +MINMAX(32, 0xff) +MINMAX(64, 0x7ff) + + /* Multiply A by 2 raised to the power N. */ float32 float32_scalbn( float32 a, int n STATUS_PARAM ) { diff --git a/fpu/softfloat.h b/fpu/softfloat.h index fd61dc4..1d37d65 100644 --- a/fpu/softfloat.h +++ b/fpu/softfloat.h @@ -333,6 +333,8 @@ int float32_le_quiet( float32, float32 STATUS_PARAM ); int float32_lt_quiet( float32, float32 STATUS_PARAM ); int float32_compare( float32, float32 STATUS_PARAM ); int float32_compare_quiet( float32, float32 STATUS_PARAM ); +float32 float32_min(float32, float32 STATUS_PARAM); +float32 float32_max(float32, float32 STATUS_PARAM); int float32_is_quiet_nan( float32 ); int float32_is_signaling_nan( float32 ); float32 float32_maybe_silence_nan( float32 ); @@ -445,6 +447,8 @@ int float64_le_quiet( float64, float64 STATUS_PARAM ); int float64_lt_quiet( float64, float64 STATUS_PARAM ); int float64_compare( float64, float64 STATUS_PARAM ); int float64_compare_quiet( float64, float64 STATUS_PARAM ); +float64 float64_min(float64, float64 STATUS_PARAM); +float64 float64_max(float64, float64 STATUS_PARAM); int float64_is_quiet_nan( float64 a ); int float64_is_signaling_nan( float64 ); float64 float64_maybe_silence_nan( float64 );