zend_float.h

/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Christian Seiler <chris_se@gmx.net>                         |
   +----------------------------------------------------------------------+
*/

#ifndef ZEND_FLOAT_H
#define ZEND_FLOAT_H

BEGIN_EXTERN_C()

/*
  Define functions for FP initialization and de-initialization.
*/
extern ZEND_API void zend_init_fpu(void);
extern ZEND_API void zend_shutdown_fpu(void);
extern ZEND_API void zend_ensure_fpu_mode(void);

END_EXTERN_C()

/* Copy of the contents of xpfpa.h (which is under public domain)
   See http://wiki.php.net/rfc/rounding for details.

   Cross Platform Floating Point Arithmetics

   This header file defines several platform-dependent macros that ensure
   equal and deterministic floating point behaviour across several platforms,
   compilers and architectures.

   The current macros are currently only used on x86 and x86_64 architectures,
   on every other architecture, these macros expand to NOPs. This assumes that
   other architectures do not have an internal precision and the operhand types
   define the computational precision of floating point operations. This
   assumption may be false, in that case, the author is interested in further
   details on the other platform.

   For further details, please visit:
   http://www.christian-seiler.de/projekte/fpmath/

   Version: 20090317 */

/*
 Implementation notes:

 x86_64:
  - Since all x86_64 compilers use SSE by default, it is probably unnecessary
    to use these macros there. We define them anyway since we are too lazy
    to differentiate the architecture. Also, the compiler option -mfpmath=i387
    justifies this decision.

 General:
  - It would be nice if one could detect whether SSE if used for math via some
    funky compiler defines and if so, make the macros go to NOPs. Any ideas
    on how to do that?

 MS Visual C:
  - Since MSVC users typically don't use autoconf or CMake, we will detect
    MSVC via compile time define. Floating point precision change isn't
    supported on 64 bit platforms, so it's NOP. See
    http://msdn.microsoft.com/en-us/library/c9676k6h(v=vs.110).aspx
*/

/* MSVC detection (MSVC people usually don't use autoconf) */
#if defined(_MSC_VER) && !defined(_WIN64)
#  define HAVE__CONTROLFP_S
#endif /* _MSC_VER */

#ifdef HAVE__CONTROLFP_S

/* float.h defines _controlfp_s */
# include <float.h>

# define XPFPA_HAVE_CW 1
# define XPFPA_CW_DATATYPE \
            unsigned int

# define XPFPA_STORE_CW(vptr) do { \
            _controlfp_s((unsigned int *)(vptr), 0, 0); \
        } while (0)

# define XPFPA_RESTORE_CW(vptr) do { \
            unsigned int _xpfpa_fpu_cw; \
            _controlfp_s(&_xpfpa_fpu_cw, *((unsigned int *)(vptr)), _MCW_PC); \
        } while (0)

# define XPFPA_DECLARE \
            unsigned int _xpfpa_fpu_oldcw, _xpfpa_fpu_cw;

# define XPFPA_SWITCH_DOUBLE() do { \
            _controlfp_s(&_xpfpa_fpu_cw, 0, 0); \
            _xpfpa_fpu_oldcw = _xpfpa_fpu_cw; \
            _controlfp_s(&_xpfpa_fpu_cw, _PC_53, _MCW_PC); \
        } while (0)
# define XPFPA_SWITCH_SINGLE() do { \
            _controlfp_s(&_xpfpa_fpu_cw, 0, 0); \
            _xpfpa_fpu_oldcw = _xpfpa_fpu_cw; \
            _controlfp_s(&_xpfpa_fpu_cw, _PC_24, _MCW_PC); \
        } while (0)
/* NOTE: This only sets internal precision. MSVC does NOT support double-
   extended precision! */
# define XPFPA_SWITCH_DOUBLE_EXTENDED() do { \
            _controlfp_s(&_xpfpa_fpu_cw, 0, 0); \
            _xpfpa_fpu_oldcw = _xpfpa_fpu_cw; \
            _controlfp_s(&_xpfpa_fpu_cw, _PC_64, _MCW_PC); \
        } while (0)
# define XPFPA_RESTORE() \
            _controlfp_s(&_xpfpa_fpu_cw, _xpfpa_fpu_oldcw, _MCW_PC)
/* We do NOT use the volatile return trick since _controlfp_s is a function
   call and thus FP registers are saved in memory anyway. However, we do use
   a variable to ensure that the expression passed into val will be evaluated
   *before* switching back contexts. */
# define XPFPA_RETURN_DOUBLE(val) \
            do { \
                double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_SINGLE(val) \
            do { \
                float _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
/* This won't work, but we add a macro for it anyway. */
# define XPFPA_RETURN_DOUBLE_EXTENDED(val) \
            do { \
                long double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)

#elif defined(HAVE__CONTROLFP)

/* float.h defines _controlfp */
# include <float.h>

# define XPFPA_DECLARE \
            unsigned int _xpfpa_fpu_oldcw;

# define XPFPA_HAVE_CW 1
# define XPFPA_CW_DATATYPE \
            unsigned int

# define XPFPA_STORE_CW(vptr) do { \
            *((unsigned int *)(vptr)) = _controlfp(0, 0); \
        } while (0)

# define XPFPA_RESTORE_CW(vptr) do { \
            _controlfp(*((unsigned int *)(vptr)), _MCW_PC); \
        } while (0)

# define XPFPA_SWITCH_DOUBLE() do { \
            _xpfpa_fpu_oldcw = _controlfp(0, 0); \
            _controlfp(_PC_53, _MCW_PC); \
        } while (0)
# define XPFPA_SWITCH_SINGLE() do { \
            _xpfpa_fpu_oldcw = _controlfp(0, 0); \
            _controlfp(_PC_24, _MCW_PC); \
        } while (0)
/* NOTE: This will only work as expected on MinGW. */
# define XPFPA_SWITCH_DOUBLE_EXTENDED() do { \
            _xpfpa_fpu_oldcw = _controlfp(0, 0); \
            _controlfp(_PC_64, _MCW_PC); \
        } while (0)
# define XPFPA_RESTORE() \
            _controlfp(_xpfpa_fpu_oldcw, _MCW_PC)
/* We do NOT use the volatile return trick since _controlfp is a function
   call and thus FP registers are saved in memory anyway. However, we do use
   a variable to ensure that the expression passed into val will be evaluated
   *before* switching back contexts. */
# define XPFPA_RETURN_DOUBLE(val) \
            do { \
                double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_SINGLE(val) \
            do { \
                float _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
/* This will only work on MinGW */
# define XPFPA_RETURN_DOUBLE_EXTENDED(val) \
            do { \
                long double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)

#elif defined(HAVE__FPU_SETCW) /* glibc systems */

/* fpu_control.h defines _FPU_[GS]ETCW */
# include <fpu_control.h>

# define XPFPA_DECLARE \
            fpu_control_t _xpfpa_fpu_oldcw, _xpfpa_fpu_cw;

# define XPFPA_HAVE_CW 1
# define XPFPA_CW_DATATYPE \
            fpu_control_t

# define XPFPA_STORE_CW(vptr) do { \
            _FPU_GETCW((*((fpu_control_t *)(vptr)))); \
        } while (0)

# define XPFPA_RESTORE_CW(vptr) do { \
            _FPU_SETCW((*((fpu_control_t *)(vptr)))); \
        } while (0)

# define XPFPA_SWITCH_DOUBLE() do { \
            _FPU_GETCW(_xpfpa_fpu_oldcw); \
            _xpfpa_fpu_cw = (_xpfpa_fpu_oldcw & ~_FPU_EXTENDED & ~_FPU_SINGLE) | _FPU_DOUBLE; \
            _FPU_SETCW(_xpfpa_fpu_cw); \
        } while (0)
# define XPFPA_SWITCH_SINGLE() do { \
            _FPU_GETCW(_xpfpa_fpu_oldcw); \
            _xpfpa_fpu_cw = (_xpfpa_fpu_oldcw & ~_FPU_EXTENDED & ~_FPU_DOUBLE) | _FPU_SINGLE; \
            _FPU_SETCW(_xpfpa_fpu_cw); \
        } while (0)
# define XPFPA_SWITCH_DOUBLE_EXTENDED()  do { \
            _FPU_GETCW(_xpfpa_fpu_oldcw); \
            _xpfpa_fpu_cw = (_xpfpa_fpu_oldcw & ~_FPU_SINGLE & ~_FPU_DOUBLE) | _FPU_EXTENDED; \
            _FPU_SETCW(_xpfpa_fpu_cw); \
        } while (0)
# define XPFPA_RESTORE() \
            _FPU_SETCW(_xpfpa_fpu_oldcw)
/* We use a temporary volatile variable (in a new block) in order to ensure
   that the optimizer does not mis-optimize the instructions. Also, a volatile
   variable ensures truncation to correct precision. */
# define XPFPA_RETURN_DOUBLE(val) \
            do { \
                volatile double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_SINGLE(val) \
            do { \
                volatile float _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_DOUBLE_EXTENDED(val) \
            do { \
                volatile long double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)

#elif defined(HAVE_FPSETPREC) /* FreeBSD */

/* fpu_control.h defines _FPU_[GS]ETCW */
# include <machine/ieeefp.h>

# define XPFPA_DECLARE \
            fp_prec_t _xpfpa_fpu_oldprec;

# define XPFPA_HAVE_CW 1
# define XPFPA_CW_DATATYPE \
            fp_prec_t

# define XPFPA_STORE_CW(vptr) do { \
            *((fp_prec_t *)(vptr)) = fpgetprec(); \
        } while (0)

# define XPFPA_RESTORE_CW(vptr) do { \
            fpsetprec(*((fp_prec_t *)(vptr))); \
        } while (0)

# define XPFPA_SWITCH_DOUBLE() do { \
            _xpfpa_fpu_oldprec = fpgetprec(); \
            fpsetprec(FP_PD); \
        } while (0)
# define XPFPA_SWITCH_SINGLE() do { \
            _xpfpa_fpu_oldprec = fpgetprec(); \
            fpsetprec(FP_PS); \
        } while (0)
# define XPFPA_SWITCH_DOUBLE_EXTENDED() do { \
            _xpfpa_fpu_oldprec = fpgetprec(); \
            fpsetprec(FP_PE); \
        } while (0)
# define XPFPA_RESTORE() \
            fpsetprec(_xpfpa_fpu_oldprec)
/* We use a temporary volatile variable (in a new block) in order to ensure
   that the optimizer does not mis-optimize the instructions. Also, a volatile
   variable ensures truncation to correct precision. */
# define XPFPA_RETURN_DOUBLE(val) \
            do { \
                volatile double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_SINGLE(val) \
            do { \
                volatile float _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_DOUBLE_EXTENDED(val) \
            do { \
                volatile long double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)

#elif defined(HAVE_FPU_INLINE_ASM_X86)

/*
  Custom x86 inline assembler implementation.

  This implementation does not use predefined wrappers of the OS / compiler
  but rather uses x86/x87 inline assembler directly. Basic instructions:

  fnstcw - Store the FPU control word in a variable
  fldcw  - Load the FPU control word from a variable

  Bits (only bits 8 and 9 are relevant, bits 0 to 7 are for other things):
     0x0yy: Single precision
     0x1yy: Reserved
     0x2yy: Double precision
     0x3yy: Double-extended precision

  We use an unsigned int for the datatype. glibc sources add __mode__ (__HI__)
  attribute to it (HI stands for half-integer according to docs). It is unclear
  what the does exactly and how portable it is.

  The assembly syntax works with GNU CC, Intel CC and Sun CC.
*/

# define XPFPA_DECLARE \
            unsigned int _xpfpa_fpu_oldcw, _xpfpa_fpu_cw;

# define XPFPA_HAVE_CW 1
# define XPFPA_CW_DATATYPE \
            unsigned int

# define XPFPA_STORE_CW(vptr) do { \
            __asm__ __volatile__ ("fnstcw %0" : "=m" (*((unsigned int *)(vptr)))); \
        } while (0)

# define XPFPA_RESTORE_CW(vptr) do { \
            __asm__ __volatile__ ("fldcw %0" : : "m" (*((unsigned int *)(vptr)))); \
        } while (0)

# define XPFPA_SWITCH_DOUBLE() do { \
            __asm__ __volatile__ ("fnstcw %0" : "=m" (*&_xpfpa_fpu_oldcw)); \
            _xpfpa_fpu_cw = (_xpfpa_fpu_oldcw & ~0x100) | 0x200; \
            __asm__ __volatile__ ("fldcw %0" : : "m" (*&_xpfpa_fpu_cw)); \
        } while (0)
# define XPFPA_SWITCH_SINGLE() do { \
            __asm__ __volatile__ ("fnstcw %0" : "=m" (*&_xpfpa_fpu_oldcw)); \
            _xpfpa_fpu_cw = (_xpfpa_fpu_oldcw & ~0x300); \
            __asm__ __volatile__ ("fldcw %0" : : "m" (*&_xpfpa_fpu_cw)); \
        } while (0)
# define XPFPA_SWITCH_DOUBLE_EXTENDED() do { \
            __asm__ __volatile__ ("fnstcw %0" : "=m" (*&_xpfpa_fpu_oldcw)); \
            _xpfpa_fpu_cw = _xpfpa_fpu_oldcw | 0x300; \
            __asm__ __volatile__ ("fldcw %0" : : "m" (*&_xpfpa_fpu_cw)); \
        } while (0)
# define XPFPA_RESTORE() \
            __asm__ __volatile__ ("fldcw %0" : : "m" (*&_xpfpa_fpu_oldcw))
/* We use a temporary volatile variable (in a new block) in order to ensure
   that the optimizer does not mis-optimize the instructions. Also, a volatile
   variable ensures truncation to correct precision. */
# define XPFPA_RETURN_DOUBLE(val) \
            do { \
                volatile double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_SINGLE(val) \
            do { \
                volatile float _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)
# define XPFPA_RETURN_DOUBLE_EXTENDED(val) \
            do { \
                volatile long double _xpfpa_result = (val); \
                XPFPA_RESTORE(); \
                return _xpfpa_result; \
            } while (0)

#else /* FPU CONTROL */

/*
  This is either not an x87 FPU or the inline assembly syntax was not
  recognized. In any case, default to NOPs for the macros and hope the
  generated code will behave as planned.
*/
# define XPFPA_DECLARE                      /* NOP */
# define XPFPA_HAVE_CW                      0
# define XPFPA_CW_DATATYPE                  unsigned int
# define XPFPA_STORE_CW(variable)           /* NOP */
# define XPFPA_RESTORE_CW(variable)         /* NOP */
# define XPFPA_SWITCH_DOUBLE()              /* NOP */
# define XPFPA_SWITCH_SINGLE()              /* NOP */
# define XPFPA_SWITCH_DOUBLE_EXTENDED()     /* NOP */
# define XPFPA_RESTORE()                    /* NOP */
# define XPFPA_RETURN_DOUBLE(val)           return (val)
# define XPFPA_RETURN_SINGLE(val)           return (val)
# define XPFPA_RETURN_DOUBLE_EXTENDED(val)  return (val)

#endif /* FPU CONTROL */

#endif