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b3b8e1eb27
Implement fused multiply-add with correct accuracy. Fused multiply-add operation has better accuracy than respective sequential execution of multiply and add operations applied on the same inputs. This is because accuracy errors accumulate in latter case. This patch implements fused multiply-add with the same accuracy as it is implemented in hardware, using 64-bit intermediate calculations. One test case example (raw bits) that this patch fixes: MADDF.S fd,fs,ft: fd = 0x22575225 fs = ft = 0x3727c5ac Fixes:e24c3bec3e("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction") Fixes:83d43305a1("MIPS: math-emu: Add support for the MIPS R6 MSUBF FPU instruction") Signed-off-by: Douglas Leung <douglas.leung@imgtec.com> Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com> Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com> Cc: Douglas Leung <douglas.leung@imgtec.com> Cc: Bo Hu <bohu@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: Jin Qian <jinqian@google.com> Cc: Paul Burton <paul.burton@imgtec.com> Cc: Petar Jovanovic <petar.jovanovic@imgtec.com> Cc: Raghu Gandham <raghu.gandham@imgtec.com> Cc: <stable@vger.kernel.org> # 4.7+ Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/16890/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/*
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* IEEE754 floating point
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* double precision internal header file
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*/
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/*
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* MIPS floating point support
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* Copyright (C) 1994-2000 Algorithmics Ltd.
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*
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* This program is free software; you can distribute it and/or modify it
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* under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <linux/compiler.h>
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#include "ieee754int.h"
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#define assert(expr) ((void)0)
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#define SP_EBIAS 127
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#define SP_EMIN (-126)
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#define SP_EMAX 127
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#define SP_FBITS 23
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#define SP_MBITS 23
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#define SP_MBIT(x) ((u32)1 << (x))
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#define SP_HIDDEN_BIT SP_MBIT(SP_FBITS)
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#define SP_SIGN_BIT SP_MBIT(31)
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#define SPSIGN(sp) (sp.sign)
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#define SPBEXP(sp) (sp.bexp)
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#define SPMANT(sp) (sp.mant)
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static inline int ieee754sp_finite(union ieee754sp x)
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{
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return SPBEXP(x) != SP_EMAX + 1 + SP_EBIAS;
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}
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/* 64 bit right shift with rounding */
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#define XSPSRS64(v, rs) \
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(((rs) >= 64) ? ((v) != 0) : ((v) >> (rs)) | ((v) << (64-(rs)) != 0))
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/* 3bit extended single precision sticky right shift */
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#define XSPSRS(v, rs) \
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((rs > (SP_FBITS+3))?1:((v) >> (rs)) | ((v) << (32-(rs)) != 0))
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#define XSPSRS1(m) \
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((m >> 1) | (m & 1))
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#define SPXSRSX1() \
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(xe++, (xm = XSPSRS1(xm)))
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#define SPXSRSY1() \
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(ye++, (ym = XSPSRS1(ym)))
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/* convert denormal to normalized with extended exponent */
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#define SPDNORMx(m,e) \
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while ((m >> SP_FBITS) == 0) { m <<= 1; e--; }
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#define SPDNORMX SPDNORMx(xm, xe)
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#define SPDNORMY SPDNORMx(ym, ye)
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#define SPDNORMZ SPDNORMx(zm, ze)
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static inline union ieee754sp buildsp(int s, int bx, unsigned m)
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{
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union ieee754sp r;
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assert((s) == 0 || (s) == 1);
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assert((bx) >= SP_EMIN - 1 + SP_EBIAS
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&& (bx) <= SP_EMAX + 1 + SP_EBIAS);
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assert(((m) >> SP_FBITS) == 0);
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r.sign = s;
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r.bexp = bx;
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r.mant = m;
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return r;
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}
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extern union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp);
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extern union ieee754sp ieee754sp_format(int, int, unsigned);
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