/* * Union to access IEEE double memory representation, indexes for double * memory representation, and some macros for double manipulation. * * Also used by packed duk_tval. Use a union for bit manipulation to * minimize aliasing issues in practice. The C99 standard does not * guarantee that this should work, but it's a very widely supported * practice for low level manipulation. * * IEEE double format summary: * * seeeeeee eeeeffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff * A B C D E F G H * * s sign bit * eee... exponent field * fff... fraction * * See http://en.wikipedia.org/wiki/Double_precision_floating-point_format. * * NaNs are represented as exponent 0x7ff and mantissa != 0. The NaN is a * signaling NaN when the highest bit of the mantissa is zero, and a quiet * NaN when the highest bit is set. * * At least three memory layouts are relevant here: * * A B C D E F G H Big endian (e.g. 68k) DUK_USE_DOUBLE_BE * H G F E D C B A Little endian (e.g. x86) DUK_USE_DOUBLE_LE * D C B A H G F E Mixed/cross endian (e.g. ARM) DUK_USE_DOUBLE_ME * * ARM is a special case: ARM double values are in mixed/cross endian * format while ARM duk_uint64_t values are in standard little endian * format (H G F E D C B A). When a double is read as a duk_uint64_t * from memory, the register will contain the (logical) value * E F G H A B C D. This requires some special handling below. * * Indexes of various types (8-bit, 16-bit, 32-bit) in memory relative to * the logical (big endian) order: * * byte order duk_uint8_t duk_uint16_t duk_uint32_t * BE 01234567 0123 01 * LE 76543210 3210 10 * ME (ARM) 32107654 1032 01 * * Some processors may alter NaN values in a floating point load+store. * For instance, on X86 a FLD + FSTP may convert a signaling NaN to a * quiet one. This is catastrophic when NaN space is used in packed * duk_tval values. See: misc/clang_aliasing.c. */ #if !defined(DUK_DBLUNION_H_INCLUDED) #define DUK_DBLUNION_H_INCLUDED /* * Union for accessing double parts, also serves as packed duk_tval */ union duk_double_union { double d; float f[2]; #if defined(DUK_USE_64BIT_OPS) duk_uint64_t ull[1]; #endif duk_uint32_t ui[2]; duk_uint16_t us[4]; duk_uint8_t uc[8]; #if defined(DUK_USE_PACKED_TVAL) void *vp[2]; /* used by packed duk_tval, assumes sizeof(void *) == 4 */ #endif }; typedef union duk_double_union duk_double_union; /* * Indexes of various types with respect to big endian (logical) layout */ #if defined(DUK_USE_DOUBLE_LE) #if defined(DUK_USE_64BIT_OPS) #define DUK_DBL_IDX_ULL0 0 #endif #define DUK_DBL_IDX_UI0 1 #define DUK_DBL_IDX_UI1 0 #define DUK_DBL_IDX_US0 3 #define DUK_DBL_IDX_US1 2 #define DUK_DBL_IDX_US2 1 #define DUK_DBL_IDX_US3 0 #define DUK_DBL_IDX_UC0 7 #define DUK_DBL_IDX_UC1 6 #define DUK_DBL_IDX_UC2 5 #define DUK_DBL_IDX_UC3 4 #define DUK_DBL_IDX_UC4 3 #define DUK_DBL_IDX_UC5 2 #define DUK_DBL_IDX_UC6 1 #define DUK_DBL_IDX_UC7 0 #define DUK_DBL_IDX_VP0 DUK_DBL_IDX_UI0 /* packed tval */ #define DUK_DBL_IDX_VP1 DUK_DBL_IDX_UI1 /* packed tval */ #elif defined(DUK_USE_DOUBLE_BE) #if defined(DUK_USE_64BIT_OPS) #define DUK_DBL_IDX_ULL0 0 #endif #define DUK_DBL_IDX_UI0 0 #define DUK_DBL_IDX_UI1 1 #define DUK_DBL_IDX_US0 0 #define DUK_DBL_IDX_US1 1 #define DUK_DBL_IDX_US2 2 #define DUK_DBL_IDX_US3 3 #define DUK_DBL_IDX_UC0 0 #define DUK_DBL_IDX_UC1 1 #define DUK_DBL_IDX_UC2 2 #define DUK_DBL_IDX_UC3 3 #define DUK_DBL_IDX_UC4 4 #define DUK_DBL_IDX_UC5 5 #define DUK_DBL_IDX_UC6 6 #define DUK_DBL_IDX_UC7 7 #define DUK_DBL_IDX_VP0 DUK_DBL_IDX_UI0 /* packed tval */ #define DUK_DBL_IDX_VP1 DUK_DBL_IDX_UI1 /* packed tval */ #elif defined(DUK_USE_DOUBLE_ME) #if defined(DUK_USE_64BIT_OPS) #define DUK_DBL_IDX_ULL0 0 /* not directly applicable, byte order differs from a double */ #endif #define DUK_DBL_IDX_UI0 0 #define DUK_DBL_IDX_UI1 1 #define DUK_DBL_IDX_US0 1 #define DUK_DBL_IDX_US1 0 #define DUK_DBL_IDX_US2 3 #define DUK_DBL_IDX_US3 2 #define DUK_DBL_IDX_UC0 3 #define DUK_DBL_IDX_UC1 2 #define DUK_DBL_IDX_UC2 1 #define DUK_DBL_IDX_UC3 0 #define DUK_DBL_IDX_UC4 7 #define DUK_DBL_IDX_UC5 6 #define DUK_DBL_IDX_UC6 5 #define DUK_DBL_IDX_UC7 4 #define DUK_DBL_IDX_VP0 DUK_DBL_IDX_UI0 /* packed tval */ #define DUK_DBL_IDX_VP1 DUK_DBL_IDX_UI1 /* packed tval */ #else #error internal error #endif /* * Helper macros for reading/writing memory representation parts, used * by duk_numconv.c and duk_tval.h. */ #define DUK_DBLUNION_SET_DOUBLE(u,v) do { \ (u)->d = (v); \ } while (0) #define DUK_DBLUNION_SET_HIGH32(u,v) do { \ (u)->ui[DUK_DBL_IDX_UI0] = (duk_uint32_t) (v); \ } while (0) #if defined(DUK_USE_64BIT_OPS) #if defined(DUK_USE_DOUBLE_ME) #define DUK_DBLUNION_SET_HIGH32_ZERO_LOW32(u,v) do { \ (u)->ull[DUK_DBL_IDX_ULL0] = (duk_uint64_t) (v); \ } while (0) #else #define DUK_DBLUNION_SET_HIGH32_ZERO_LOW32(u,v) do { \ (u)->ull[DUK_DBL_IDX_ULL0] = ((duk_uint64_t) (v)) << 32; \ } while (0) #endif #else /* DUK_USE_64BIT_OPS */ #define DUK_DBLUNION_SET_HIGH32_ZERO_LOW32(u,v) do { \ (u)->ui[DUK_DBL_IDX_UI0] = (duk_uint32_t) (v); \ (u)->ui[DUK_DBL_IDX_UI1] = (duk_uint32_t) 0; \ } while (0) #endif /* DUK_USE_64BIT_OPS */ #define DUK_DBLUNION_SET_LOW32(u,v) do { \ (u)->ui[DUK_DBL_IDX_UI1] = (duk_uint32_t) (v); \ } while (0) #define DUK_DBLUNION_GET_DOUBLE(u) ((u)->d) #define DUK_DBLUNION_GET_HIGH32(u) ((u)->ui[DUK_DBL_IDX_UI0]) #define DUK_DBLUNION_GET_LOW32(u) ((u)->ui[DUK_DBL_IDX_UI1]) #if defined(DUK_USE_64BIT_OPS) #if defined(DUK_USE_DOUBLE_ME) #define DUK_DBLUNION_SET_UINT64(u,v) do { \ (u)->ui[DUK_DBL_IDX_UI0] = (duk_uint32_t) ((v) >> 32); \ (u)->ui[DUK_DBL_IDX_UI1] = (duk_uint32_t) (v); \ } while (0) #define DUK_DBLUNION_GET_UINT64(u) \ ((((duk_uint64_t) (u)->ui[DUK_DBL_IDX_UI0]) << 32) | \ ((duk_uint64_t) (u)->ui[DUK_DBL_IDX_UI1])) #else #define DUK_DBLUNION_SET_UINT64(u,v) do { \ (u)->ull[DUK_DBL_IDX_ULL0] = (duk_uint64_t) (v); \ } while (0) #define DUK_DBLUNION_GET_UINT64(u) ((u)->ull[DUK_DBL_IDX_ULL0]) #endif #define DUK_DBLUNION_SET_INT64(u,v) DUK_DBLUNION_SET_UINT64((u), (duk_uint64_t) (v)) #define DUK_DBLUNION_GET_INT64(u) ((duk_int64_t) DUK_DBLUNION_GET_UINT64((u))) #endif /* DUK_USE_64BIT_OPS */ /* * Double NaN manipulation macros related to NaN normalization needed when * using the packed duk_tval representation. NaN normalization is necessary * to keep double values compatible with the duk_tval format. * * When packed duk_tval is used, the NaN space is used to store pointers * and other tagged values in addition to NaNs. Actual NaNs are normalized * to a specific quiet NaN. The macros below are used by the implementation * to check and normalize NaN values when they might be created. The macros * are essentially NOPs when the non-packed duk_tval representation is used. * * A FULL check is exact and checks all bits. A NOTFULL check is used by * the packed duk_tval and works correctly for all NaNs except those that * begin with 0x7ff0. Since the 'normalized NaN' values used with packed * duk_tval begin with 0x7ff8, the partial check is reliable when packed * duk_tval is used. The 0x7ff8 prefix means the normalized NaN will be a * quiet NaN regardless of its remaining lower bits. * * The ME variant below is specifically for ARM byte order, which has the * feature that while doubles have a mixed byte order (32107654), unsigned * long long values has a little endian byte order (76543210). When writing * a logical double value through a ULL pointer, the 32-bit words need to be * swapped; hence the #if defined()s below for ULL writes with DUK_USE_DOUBLE_ME. * This is not full ARM support but suffices for some environments. */ #if defined(DUK_USE_64BIT_OPS) #if defined(DUK_USE_DOUBLE_ME) /* Macros for 64-bit ops + mixed endian doubles. */ #define DUK__DBLUNION_SET_NAN_FULL(u) do { \ (u)->ull[DUK_DBL_IDX_ULL0] = DUK_U64_CONSTANT(0x000000007ff80000); \ } while (0) #define DUK__DBLUNION_IS_NAN_FULL(u) \ ((((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0x000000007ff00000)) == DUK_U64_CONSTANT(0x000000007ff00000)) && \ ((((u)->ull[DUK_DBL_IDX_ULL0]) & DUK_U64_CONSTANT(0xffffffff000fffff)) != 0)) #define DUK__DBLUNION_IS_NORMALIZED_NAN_FULL(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x000000007ff80000)) #define DUK__DBLUNION_IS_ANYINF(u) \ (((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0xffffffff7fffffff)) == DUK_U64_CONSTANT(0x000000007ff00000)) #define DUK__DBLUNION_IS_POSINF(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x000000007ff00000)) #define DUK__DBLUNION_IS_NEGINF(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x00000000fff00000)) #define DUK__DBLUNION_IS_ANYZERO(u) \ (((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0xffffffff7fffffff)) == DUK_U64_CONSTANT(0x0000000000000000)) #define DUK__DBLUNION_IS_POSZERO(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x0000000000000000)) #define DUK__DBLUNION_IS_NEGZERO(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x0000000080000000)) #else /* Macros for 64-bit ops + big/little endian doubles. */ #define DUK__DBLUNION_SET_NAN_FULL(u) do { \ (u)->ull[DUK_DBL_IDX_ULL0] = DUK_U64_CONSTANT(0x7ff8000000000000); \ } while (0) #define DUK__DBLUNION_IS_NAN_FULL(u) \ ((((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0x7ff0000000000000)) == DUK_U64_CONSTANT(0x7ff0000000000000)) && \ ((((u)->ull[DUK_DBL_IDX_ULL0]) & DUK_U64_CONSTANT(0x000fffffffffffff)) != 0)) #define DUK__DBLUNION_IS_NORMALIZED_NAN_FULL(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x7ff8000000000000)) #define DUK__DBLUNION_IS_ANYINF(u) \ (((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0x7fffffffffffffff)) == DUK_U64_CONSTANT(0x7ff0000000000000)) #define DUK__DBLUNION_IS_POSINF(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x7ff0000000000000)) #define DUK__DBLUNION_IS_NEGINF(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0xfff0000000000000)) #define DUK__DBLUNION_IS_ANYZERO(u) \ (((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0x7fffffffffffffff)) == DUK_U64_CONSTANT(0x0000000000000000)) #define DUK__DBLUNION_IS_POSZERO(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x0000000000000000)) #define DUK__DBLUNION_IS_NEGZERO(u) \ ((u)->ull[DUK_DBL_IDX_ULL0] == DUK_U64_CONSTANT(0x8000000000000000)) #endif #else /* DUK_USE_64BIT_OPS */ /* Macros for no 64-bit ops, any endianness. */ #define DUK__DBLUNION_SET_NAN_FULL(u) do { \ (u)->ui[DUK_DBL_IDX_UI0] = (duk_uint32_t) 0x7ff80000UL; \ (u)->ui[DUK_DBL_IDX_UI1] = (duk_uint32_t) 0x00000000UL; \ } while (0) #define DUK__DBLUNION_IS_NAN_FULL(u) \ ((((u)->ui[DUK_DBL_IDX_UI0] & 0x7ff00000UL) == 0x7ff00000UL) && \ (((u)->ui[DUK_DBL_IDX_UI0] & 0x000fffffUL) != 0 || \ (u)->ui[DUK_DBL_IDX_UI1] != 0)) #define DUK__DBLUNION_IS_NORMALIZED_NAN_FULL(u) \ (((u)->ui[DUK_DBL_IDX_UI0] == 0x7ff80000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_ANYINF(u) \ ((((u)->ui[DUK_DBL_IDX_UI0] & 0x7fffffffUL) == 0x7ff00000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_POSINF(u) \ (((u)->ui[DUK_DBL_IDX_UI0] == 0x7ff00000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_NEGINF(u) \ (((u)->ui[DUK_DBL_IDX_UI0] == 0xfff00000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_ANYZERO(u) \ ((((u)->ui[DUK_DBL_IDX_UI0] & 0x7fffffffUL) == 0x00000000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_POSZERO(u) \ (((u)->ui[DUK_DBL_IDX_UI0] == 0x00000000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #define DUK__DBLUNION_IS_NEGZERO(u) \ (((u)->ui[DUK_DBL_IDX_UI0] == 0x80000000UL) && \ ((u)->ui[DUK_DBL_IDX_UI1] == 0x00000000UL)) #endif /* DUK_USE_64BIT_OPS */ #define DUK__DBLUNION_SET_NAN_NOTFULL(u) do { \ (u)->us[DUK_DBL_IDX_US0] = 0x7ff8UL; \ } while (0) #define DUK__DBLUNION_IS_NAN_NOTFULL(u) \ /* E == 0x7ff, topmost four bits of F != 0 => assume NaN */ \ ((((u)->us[DUK_DBL_IDX_US0] & 0x7ff0UL) == 0x7ff0UL) && \ (((u)->us[DUK_DBL_IDX_US0] & 0x000fUL) != 0x0000UL)) #define DUK__DBLUNION_IS_NORMALIZED_NAN_NOTFULL(u) \ /* E == 0x7ff, F == 8 => normalized NaN */ \ ((u)->us[DUK_DBL_IDX_US0] == 0x7ff8UL) #define DUK__DBLUNION_NORMALIZE_NAN_CHECK_FULL(u) do { \ if (DUK__DBLUNION_IS_NAN_FULL((u))) { \ DUK__DBLUNION_SET_NAN_FULL((u)); \ } \ } while (0) #define DUK__DBLUNION_NORMALIZE_NAN_CHECK_NOTFULL(u) do { \ if (DUK__DBLUNION_IS_NAN_NOTFULL((u))) { \ DUK__DBLUNION_SET_NAN_NOTFULL((u)); \ } \ } while (0) /* Concrete macros for NaN handling used by the implementation internals. * Chosen so that they match the duk_tval representation: with a packed * duk_tval, ensure NaNs are properly normalized; with a non-packed duk_tval * these are essentially NOPs. */ #if defined(DUK_USE_PACKED_TVAL) #if defined(DUK_USE_FULL_TVAL) #define DUK_DBLUNION_NORMALIZE_NAN_CHECK(u) DUK__DBLUNION_NORMALIZE_NAN_CHECK_FULL((u)) #define DUK_DBLUNION_IS_NAN(u) DUK__DBLUNION_IS_NAN_FULL((u)) #define DUK_DBLUNION_IS_NORMALIZED_NAN(u) DUK__DBLUNION_IS_NORMALIZED_NAN_FULL((u)) #define DUK_DBLUNION_SET_NAN(d) DUK__DBLUNION_SET_NAN_FULL((d)) #else #define DUK_DBLUNION_NORMALIZE_NAN_CHECK(u) DUK__DBLUNION_NORMALIZE_NAN_CHECK_NOTFULL((u)) #define DUK_DBLUNION_IS_NAN(u) DUK__DBLUNION_IS_NAN_NOTFULL((u)) #define DUK_DBLUNION_IS_NORMALIZED_NAN(u) DUK__DBLUNION_IS_NORMALIZED_NAN_NOTFULL((u)) #define DUK_DBLUNION_SET_NAN(d) DUK__DBLUNION_SET_NAN_NOTFULL((d)) #endif #define DUK_DBLUNION_IS_NORMALIZED(u) \ (!DUK_DBLUNION_IS_NAN((u)) || /* either not a NaN */ \ DUK_DBLUNION_IS_NORMALIZED_NAN((u))) /* or is a normalized NaN */ #else /* DUK_USE_PACKED_TVAL */ #define DUK_DBLUNION_NORMALIZE_NAN_CHECK(u) /* nop: no need to normalize */ #define DUK_DBLUNION_IS_NAN(u) DUK__DBLUNION_IS_NAN_FULL((u)) /* (DUK_ISNAN((u)->d)) */ #define DUK_DBLUNION_IS_NORMALIZED_NAN(u) DUK__DBLUNION_IS_NAN_FULL((u)) /* (DUK_ISNAN((u)->d)) */ #define DUK_DBLUNION_IS_NORMALIZED(u) 1 /* all doubles are considered normalized */ #define DUK_DBLUNION_SET_NAN(u) do { \ /* in non-packed representation we don't care about which NaN is used */ \ (u)->d = DUK_DOUBLE_NAN; \ } while (0) #endif /* DUK_USE_PACKED_TVAL */ #define DUK_DBLUNION_IS_ANYINF(u) DUK__DBLUNION_IS_ANYINF((u)) #define DUK_DBLUNION_IS_POSINF(u) DUK__DBLUNION_IS_POSINF((u)) #define DUK_DBLUNION_IS_NEGINF(u) DUK__DBLUNION_IS_NEGINF((u)) #define DUK_DBLUNION_IS_ANYZERO(u) DUK__DBLUNION_IS_ANYZERO((u)) #define DUK_DBLUNION_IS_POSZERO(u) DUK__DBLUNION_IS_POSZERO((u)) #define DUK_DBLUNION_IS_NEGZERO(u) DUK__DBLUNION_IS_NEGZERO((u)) /* XXX: native 64-bit byteswaps when available */ /* 64-bit byteswap, same operation independent of target endianness. */ #define DUK_DBLUNION_BSWAP64(u) do { \ duk_uint32_t duk__bswaptmp1, duk__bswaptmp2; \ duk__bswaptmp1 = (u)->ui[0]; \ duk__bswaptmp2 = (u)->ui[1]; \ duk__bswaptmp1 = DUK_BSWAP32(duk__bswaptmp1); \ duk__bswaptmp2 = DUK_BSWAP32(duk__bswaptmp2); \ (u)->ui[0] = duk__bswaptmp2; \ (u)->ui[1] = duk__bswaptmp1; \ } while (0) /* Byteswap an IEEE double in the duk_double_union from host to network * order. For a big endian target this is a no-op. */ #if defined(DUK_USE_DOUBLE_LE) #define DUK_DBLUNION_DOUBLE_HTON(u) do { \ duk_uint32_t duk__bswaptmp1, duk__bswaptmp2; \ duk__bswaptmp1 = (u)->ui[0]; \ duk__bswaptmp2 = (u)->ui[1]; \ duk__bswaptmp1 = DUK_BSWAP32(duk__bswaptmp1); \ duk__bswaptmp2 = DUK_BSWAP32(duk__bswaptmp2); \ (u)->ui[0] = duk__bswaptmp2; \ (u)->ui[1] = duk__bswaptmp1; \ } while (0) #elif defined(DUK_USE_DOUBLE_ME) #define DUK_DBLUNION_DOUBLE_HTON(u) do { \ duk_uint32_t duk__bswaptmp1, duk__bswaptmp2; \ duk__bswaptmp1 = (u)->ui[0]; \ duk__bswaptmp2 = (u)->ui[1]; \ duk__bswaptmp1 = DUK_BSWAP32(duk__bswaptmp1); \ duk__bswaptmp2 = DUK_BSWAP32(duk__bswaptmp2); \ (u)->ui[0] = duk__bswaptmp1; \ (u)->ui[1] = duk__bswaptmp2; \ } while (0) #elif defined(DUK_USE_DOUBLE_BE) #define DUK_DBLUNION_DOUBLE_HTON(u) do { } while (0) #else #error internal error, double endianness insane #endif /* Reverse operation is the same. */ #define DUK_DBLUNION_DOUBLE_NTOH(u) DUK_DBLUNION_DOUBLE_HTON((u)) /* Some sign bit helpers. */ #if defined(DUK_USE_64BIT_OPS) #define DUK_DBLUNION_HAS_SIGNBIT(u) (((u)->ull[DUK_DBL_IDX_ULL0] & DUK_U64_CONSTANT(0x8000000000000000)) != 0) #define DUK_DBLUNION_GET_SIGNBIT(u) (((u)->ull[DUK_DBL_IDX_ULL0] >> 63U)) #else #define DUK_DBLUNION_HAS_SIGNBIT(u) (((u)->ui[DUK_DBL_IDX_UI0] & 0x80000000UL) != 0) #define DUK_DBLUNION_GET_SIGNBIT(u) (((u)->ui[DUK_DBL_IDX_UI0] >> 31U)) #endif #endif /* DUK_DBLUNION_H_INCLUDED */