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linux/arch/mips/math-emu/ieee754.h
Maciej W. Rozycki 90d53a91fb MIPS: math-emu: Add IEEE Std 754-2008 NaN encoding emulation 
Implement IEEE Std 754-2008 NaN encoding wired to the state of the
FCSR.NAN2008 bit.  Make the interpretation of the quiet bit in NaN data
as follows:

* in the legacy mode originally defined by the MIPS architecture the
  value of 1 denotes an sNaN whereas the value of 0 denotes a qNaN,

* in the 2008 mode introduced with revision 5 of the MIPS architecture
  the value of 0 denotes an sNaN whereas the value of 1 denotes a qNaN,
  following the definition of the preferred NaN encoding introduced with
  IEEE Std 754-2008.

In the 2008 mode, following the requirement of the said standard, quiet
an sNaN where needed by setting the quiet bit to 1 and leaving all the
NaN payload bits unchanged.

Update format conversion operations according to the rules set by IEEE
Std 754-2008 and the MIPS architecture.  Specifically:

* propagate NaN payload bits through conversions between floating-point
  formats such that as much information as possible is preserved and
  specifically a conversion from a narrower format to a wider format and
  then back to the original format does not change a qNaN payload in any
  way,

* conversions from a floating-point to an integer format where the
  source is a NaN, infinity or a value that would convert to an integer
  outside the range of the result format produce, under the default
  exception handling, the respective values defined by the MIPS
  architecture.

In full FPU emulation set the FIR.HAS2008 bit to 1, however do not make
any further FCSR bits writable.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11477/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2016-01-20 00:39:20 +01:00

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/*
* MIPS floating point support
* Copyright (C) 1994-2000 Algorithmics Ltd.
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Nov 7, 2000
* Modification to allow integration with Linux kernel
*
* Kevin D. Kissell, kevink@mips.com and Carsten Langgard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
#ifndef __ARCH_MIPS_MATH_EMU_IEEE754_H
#define __ARCH_MIPS_MATH_EMU_IEEE754_H
#include <linux/compiler.h>
#include <asm/byteorder.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <asm/bitfield.h>
union ieee754dp {
struct {
__BITFIELD_FIELD(unsigned int sign:1,
__BITFIELD_FIELD(unsigned int bexp:11,
__BITFIELD_FIELD(u64 mant:52,
;)))
};
u64 bits;
};
union ieee754sp {
struct {
__BITFIELD_FIELD(unsigned sign:1,
__BITFIELD_FIELD(unsigned bexp:8,
__BITFIELD_FIELD(unsigned mant:23,
;)))
};
u32 bits;
};
/*
* single precision (often aka float)
*/
int ieee754sp_class(union ieee754sp x);
union ieee754sp ieee754sp_abs(union ieee754sp x);
union ieee754sp ieee754sp_neg(union ieee754sp x);
union ieee754sp ieee754sp_add(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_sub(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fint(int x);
union ieee754sp ieee754sp_flong(s64 x);
union ieee754sp ieee754sp_fdp(union ieee754dp x);
int ieee754sp_tint(union ieee754sp x);
s64 ieee754sp_tlong(union ieee754sp x);
int ieee754sp_cmp(union ieee754sp x, union ieee754sp y, int cop, int sig);
union ieee754sp ieee754sp_sqrt(union ieee754sp x);
union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
union ieee754sp y);
union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
union ieee754sp y);
int ieee754sp_2008class(union ieee754sp x);
union ieee754sp ieee754sp_fmin(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y);
/*
* double precision (often aka double)
*/
int ieee754dp_class(union ieee754dp x);
union ieee754dp ieee754dp_add(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_sub(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_mul(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_abs(union ieee754dp x);
union ieee754dp ieee754dp_neg(union ieee754dp x);
union ieee754dp ieee754dp_fint(int x);
union ieee754dp ieee754dp_flong(s64 x);
union ieee754dp ieee754dp_fsp(union ieee754sp x);
int ieee754dp_tint(union ieee754dp x);
s64 ieee754dp_tlong(union ieee754dp x);
int ieee754dp_cmp(union ieee754dp x, union ieee754dp y, int cop, int sig);
union ieee754dp ieee754dp_sqrt(union ieee754dp x);
union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
union ieee754dp y);
union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
union ieee754dp y);
int ieee754dp_2008class(union ieee754dp x);
union ieee754dp ieee754dp_fmin(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmax(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y);
/* 5 types of floating point number
*/
enum {
IEEE754_CLASS_NORM = 0x00,
IEEE754_CLASS_ZERO = 0x01,
IEEE754_CLASS_DNORM = 0x02,
IEEE754_CLASS_INF = 0x03,
IEEE754_CLASS_SNAN = 0x04,
IEEE754_CLASS_QNAN = 0x05,
};
/* exception numbers */
#define IEEE754_INEXACT 0x01
#define IEEE754_UNDERFLOW 0x02
#define IEEE754_OVERFLOW 0x04
#define IEEE754_ZERO_DIVIDE 0x08
#define IEEE754_INVALID_OPERATION 0x10
/* cmp operators
*/
#define IEEE754_CLT 0x01
#define IEEE754_CEQ 0x02
#define IEEE754_CGT 0x04
#define IEEE754_CUN 0x08
/*
* The control status register
*/
struct _ieee754_csr {
__BITFIELD_FIELD(unsigned fcc:7, /* condition[7:1] */
__BITFIELD_FIELD(unsigned nod:1, /* set 1 for no denormals */
__BITFIELD_FIELD(unsigned c:1, /* condition[0] */
__BITFIELD_FIELD(unsigned pad0:3,
__BITFIELD_FIELD(unsigned abs2008:1, /* IEEE 754-2008 ABS/NEG.fmt */
__BITFIELD_FIELD(unsigned nan2008:1, /* IEEE 754-2008 NaN mode */
__BITFIELD_FIELD(unsigned cx:6, /* exceptions this operation */
__BITFIELD_FIELD(unsigned mx:5, /* exception enable mask */
__BITFIELD_FIELD(unsigned sx:5, /* exceptions total */
__BITFIELD_FIELD(unsigned rm:2, /* current rounding mode */
;))))))))))
};
#define ieee754_csr (*(struct _ieee754_csr *)(&current->thread.fpu.fcr31))
static inline unsigned ieee754_getrm(void)
{
return (ieee754_csr.rm);
}
static inline unsigned ieee754_setrm(unsigned rm)
{
return (ieee754_csr.rm = rm);
}
/*
* get current exceptions
*/
static inline unsigned ieee754_getcx(void)
{
return (ieee754_csr.cx);
}
/* test for current exception condition
*/
static inline int ieee754_cxtest(unsigned n)
{
return (ieee754_csr.cx & n);
}
/*
* get sticky exceptions
*/
static inline unsigned ieee754_getsx(void)
{
return (ieee754_csr.sx);
}
/* clear sticky conditions
*/
static inline unsigned ieee754_clrsx(void)
{
return (ieee754_csr.sx = 0);
}
/* test for sticky exception condition
*/
static inline int ieee754_sxtest(unsigned n)
{
return (ieee754_csr.sx & n);
}
/* debugging */
union ieee754sp ieee754sp_dump(char *s, union ieee754sp x);
union ieee754dp ieee754dp_dump(char *s, union ieee754dp x);
#define IEEE754_SPCVAL_PZERO 0 /* +0.0 */
#define IEEE754_SPCVAL_NZERO 1 /* -0.0 */
#define IEEE754_SPCVAL_PONE 2 /* +1.0 */
#define IEEE754_SPCVAL_NONE 3 /* -1.0 */
#define IEEE754_SPCVAL_PTEN 4 /* +10.0 */
#define IEEE754_SPCVAL_NTEN 5 /* -10.0 */
#define IEEE754_SPCVAL_PINFINITY 6 /* +inf */
#define IEEE754_SPCVAL_NINFINITY 7 /* -inf */
#define IEEE754_SPCVAL_INDEF_LEG 8 /* legacy quiet NaN */
#define IEEE754_SPCVAL_INDEF_2008 9 /* IEEE 754-2008 quiet NaN */
#define IEEE754_SPCVAL_PMAX 10 /* +max norm */
#define IEEE754_SPCVAL_NMAX 11 /* -max norm */
#define IEEE754_SPCVAL_PMIN 12 /* +min norm */
#define IEEE754_SPCVAL_NMIN 13 /* -min norm */
#define IEEE754_SPCVAL_PMIND 14 /* +min denorm */
#define IEEE754_SPCVAL_NMIND 15 /* -min denorm */
#define IEEE754_SPCVAL_P1E31 16 /* + 1.0e31 */
#define IEEE754_SPCVAL_P1E63 17 /* + 1.0e63 */
extern const union ieee754dp __ieee754dp_spcvals[];
extern const union ieee754sp __ieee754sp_spcvals[];
#define ieee754dp_spcvals ((const union ieee754dp *)__ieee754dp_spcvals)
#define ieee754sp_spcvals ((const union ieee754sp *)__ieee754sp_spcvals)
/*
* Return infinity with given sign
*/
#define ieee754dp_inf(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
#define ieee754dp_zero(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754dp_one(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754dp_ten(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
#define ieee754dp_indef() (ieee754dp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
ieee754_csr.nan2008])
#define ieee754dp_max(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754dp_min(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754dp_mind(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
#define ieee754dp_1e31() (ieee754dp_spcvals[IEEE754_SPCVAL_P1E31])
#define ieee754dp_1e63() (ieee754dp_spcvals[IEEE754_SPCVAL_P1E63])
#define ieee754sp_inf(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
#define ieee754sp_zero(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754sp_one(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754sp_ten(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
#define ieee754sp_indef() (ieee754sp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
ieee754_csr.nan2008])
#define ieee754sp_max(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754sp_min(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754sp_mind(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
#define ieee754sp_1e31() (ieee754sp_spcvals[IEEE754_SPCVAL_P1E31])
#define ieee754sp_1e63() (ieee754sp_spcvals[IEEE754_SPCVAL_P1E63])
/*
* Indefinite integer value
*/
static inline int ieee754si_indef(void)
{
return ieee754_csr.nan2008 ? 0 : INT_MAX;
}
static inline s64 ieee754di_indef(void)
{
return ieee754_csr.nan2008 ? 0 : S64_MAX;
}
/*
* Overflow integer value
*/
static inline int ieee754si_overflow(int xs)
{
return ieee754_csr.nan2008 && xs ? INT_MIN : INT_MAX;
}
static inline s64 ieee754di_overflow(int xs)
{
return ieee754_csr.nan2008 && xs ? S64_MIN : S64_MAX;
}
/* result types for xctx.rt */
#define IEEE754_RT_SP 0
#define IEEE754_RT_DP 1
#define IEEE754_RT_XP 2
#define IEEE754_RT_SI 3
#define IEEE754_RT_DI 4
/* compat */
#define ieee754dp_fix(x) ieee754dp_tint(x)
#define ieee754sp_fix(x) ieee754sp_tint(x)
#endif /* __ARCH_MIPS_MATH_EMU_IEEE754_H */
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