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Edit File: pycore_pymath.h
#ifndef Py_INTERNAL_PYMATH_H #define Py_INTERNAL_PYMATH_H #ifdef __cplusplus extern "C" { #endif #ifndef Py_BUILD_CORE # error "this header requires Py_BUILD_CORE define" #endif /* _Py_ADJUST_ERANGE1(x) * _Py_ADJUST_ERANGE2(x, y) * Set errno to 0 before calling a libm function, and invoke one of these * macros after, passing the function result(s) (_Py_ADJUST_ERANGE2 is useful * for functions returning complex results). This makes two kinds of * adjustments to errno: (A) If it looks like the platform libm set * errno=ERANGE due to underflow, clear errno. (B) If it looks like the * platform libm overflowed but didn't set errno, force errno to ERANGE. In * effect, we're trying to force a useful implementation of C89 errno * behavior. * Caution: * This isn't reliable. C99 no longer requires libm to set errno under * any exceptional condition, but does require +- HUGE_VAL return * values on overflow. A 754 box *probably* maps HUGE_VAL to a * double infinity, and we're cool if that's so, unless the input * was an infinity and an infinity is the expected result. A C89 * system sets errno to ERANGE, so we check for that too. We're * out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or * if the returned result is a NaN, or if a C89 box returns HUGE_VAL * in non-overflow cases. */ static inline void _Py_ADJUST_ERANGE1(double x) { if (errno == 0) { if (x == Py_HUGE_VAL || x == -Py_HUGE_VAL) { errno = ERANGE; } } else if (errno == ERANGE && x == 0.0) { errno = 0; } } static inline void _Py_ADJUST_ERANGE2(double x, double y) { if (x == Py_HUGE_VAL || x == -Py_HUGE_VAL || y == Py_HUGE_VAL || y == -Py_HUGE_VAL) { if (errno == 0) { errno = ERANGE; } } else if (errno == ERANGE) { errno = 0; } } // Return whether integral type *type* is signed or not. #define _Py_IntegralTypeSigned(type) \ ((type)(-1) < 0) // Return the maximum value of integral type *type*. #define _Py_IntegralTypeMax(type) \ ((_Py_IntegralTypeSigned(type)) ? (((((type)1 << (sizeof(type)*CHAR_BIT - 2)) - 1) << 1) + 1) : ~(type)0) // Return the minimum value of integral type *type*. #define _Py_IntegralTypeMin(type) \ ((_Py_IntegralTypeSigned(type)) ? -_Py_IntegralTypeMax(type) - 1 : 0) // Check whether *v* is in the range of integral type *type*. This is most // useful if *v* is floating-point, since demoting a floating-point *v* to an // integral type that cannot represent *v*'s integral part is undefined // behavior. #define _Py_InIntegralTypeRange(type, v) \ (_Py_IntegralTypeMin(type) <= v && v <= _Py_IntegralTypeMax(type)) //--- HAVE_PY_SET_53BIT_PRECISION macro ------------------------------------ // // The functions _Py_dg_strtod() and _Py_dg_dtoa() in Python/dtoa.c (which are // required to support the short float repr introduced in Python 3.1) require // that the floating-point unit that's being used for arithmetic operations on // C doubles is set to use 53-bit precision. It also requires that the FPU // rounding mode is round-half-to-even, but that's less often an issue. // // If your FPU isn't already set to 53-bit precision/round-half-to-even, and // you want to make use of _Py_dg_strtod() and _Py_dg_dtoa(), then you should: // // #define HAVE_PY_SET_53BIT_PRECISION 1 // // and also give appropriate definitions for the following three macros: // // * _Py_SET_53BIT_PRECISION_HEADER: any variable declarations needed to // use the two macros below. // * _Py_SET_53BIT_PRECISION_START: store original FPU settings, and // set FPU to 53-bit precision/round-half-to-even // * _Py_SET_53BIT_PRECISION_END: restore original FPU settings // // The macros are designed to be used within a single C function: see // Python/pystrtod.c for an example of their use. // Get and set x87 control word for gcc/x86 #ifdef HAVE_GCC_ASM_FOR_X87 #define HAVE_PY_SET_53BIT_PRECISION 1 // Functions defined in Python/pymath.c extern unsigned short _Py_get_387controlword(void); extern void _Py_set_387controlword(unsigned short); #define _Py_SET_53BIT_PRECISION_HEADER \ unsigned short old_387controlword, new_387controlword #define _Py_SET_53BIT_PRECISION_START \ do { \ old_387controlword = _Py_get_387controlword(); \ new_387controlword = (old_387controlword & ~0x0f00) | 0x0200; \ if (new_387controlword != old_387controlword) { \ _Py_set_387controlword(new_387controlword); \ } \ } while (0) #define _Py_SET_53BIT_PRECISION_END \ do { \ if (new_387controlword != old_387controlword) { \ _Py_set_387controlword(old_387controlword); \ } \ } while (0) #endif // Get and set x87 control word for VisualStudio/x86. // x87 is not supported in 64-bit or ARM. #if defined(_MSC_VER) && !defined(_WIN64) && !defined(_M_ARM) #define HAVE_PY_SET_53BIT_PRECISION 1 #include <float.h> // __control87_2() #define _Py_SET_53BIT_PRECISION_HEADER \ unsigned int old_387controlword, new_387controlword, out_387controlword // We use the __control87_2 function to set only the x87 control word. // The SSE control word is unaffected. #define _Py_SET_53BIT_PRECISION_START \ do { \ __control87_2(0, 0, &old_387controlword, NULL); \ new_387controlword = \ (old_387controlword & ~(_MCW_PC | _MCW_RC)) | (_PC_53 | _RC_NEAR); \ if (new_387controlword != old_387controlword) { \ __control87_2(new_387controlword, _MCW_PC | _MCW_RC, \ &out_387controlword, NULL); \ } \ } while (0) #define _Py_SET_53BIT_PRECISION_END \ do { \ if (new_387controlword != old_387controlword) { \ __control87_2(old_387controlword, _MCW_PC | _MCW_RC, \ &out_387controlword, NULL); \ } \ } while (0) #endif // MC68881 #ifdef HAVE_GCC_ASM_FOR_MC68881 #define HAVE_PY_SET_53BIT_PRECISION 1 #define _Py_SET_53BIT_PRECISION_HEADER \ unsigned int old_fpcr, new_fpcr #define _Py_SET_53BIT_PRECISION_START \ do { \ __asm__ ("fmove.l %%fpcr,%0" : "=g" (old_fpcr)); \ /* Set double precision / round to nearest. */ \ new_fpcr = (old_fpcr & ~0xf0) | 0x80; \ if (new_fpcr != old_fpcr) { \ __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (new_fpcr));\ } \ } while (0) #define _Py_SET_53BIT_PRECISION_END \ do { \ if (new_fpcr != old_fpcr) { \ __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (old_fpcr)); \ } \ } while (0) #endif // Default definitions are empty #ifndef _Py_SET_53BIT_PRECISION_HEADER # define _Py_SET_53BIT_PRECISION_HEADER # define _Py_SET_53BIT_PRECISION_START # define _Py_SET_53BIT_PRECISION_END #endif //--- _PY_SHORT_FLOAT_REPR macro ------------------------------------------- // If we can't guarantee 53-bit precision, don't use the code // in Python/dtoa.c, but fall back to standard code. This // means that repr of a float will be long (17 significant digits). // // Realistically, there are two things that could go wrong: // // (1) doubles aren't IEEE 754 doubles, or // (2) we're on x86 with the rounding precision set to 64-bits // (extended precision), and we don't know how to change // the rounding precision. #if !defined(DOUBLE_IS_LITTLE_ENDIAN_IEEE754) && \ !defined(DOUBLE_IS_BIG_ENDIAN_IEEE754) && \ !defined(DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754) # define _PY_SHORT_FLOAT_REPR 0 #endif // Double rounding is symptomatic of use of extended precision on x86. // If we're seeing double rounding, and we don't have any mechanism available // for changing the FPU rounding precision, then don't use Python/dtoa.c. #if defined(X87_DOUBLE_ROUNDING) && !defined(HAVE_PY_SET_53BIT_PRECISION) # define _PY_SHORT_FLOAT_REPR 0 #endif #ifndef _PY_SHORT_FLOAT_REPR # define _PY_SHORT_FLOAT_REPR 1 #endif #ifdef __cplusplus } #endif #endif /* !Py_INTERNAL_PYMATH_H */