diff options
Diffstat (limited to 'py/misc.h')
| -rw-r--r-- | py/misc.h | 105 |
1 files changed, 98 insertions, 7 deletions
@@ -33,10 +33,15 @@ #include <stdbool.h> #include <stdint.h> #include <stddef.h> +#include <limits.h> typedef unsigned char byte; typedef unsigned int uint; +#ifndef __has_builtin +#define __has_builtin(x) (0) +#endif + /** generic ops *************************************************/ #ifndef MIN @@ -374,26 +379,23 @@ static inline bool mp_check(bool value) { static inline uint32_t mp_popcount(uint32_t x) { return __popcnt(x); } -#else +#else // _MSC_VER #define mp_clz(x) __builtin_clz(x) #define mp_clzl(x) __builtin_clzl(x) #define mp_clzll(x) __builtin_clzll(x) #define mp_ctz(x) __builtin_ctz(x) #define mp_check(x) (x) -#if defined __has_builtin #if __has_builtin(__builtin_popcount) #define mp_popcount(x) __builtin_popcount(x) -#endif -#endif -#if !defined(mp_popcount) +#else static inline uint32_t mp_popcount(uint32_t x) { x = x - ((x >> 1) & 0x55555555); x = (x & 0x33333333) + ((x >> 2) & 0x33333333); x = (x + (x >> 4)) & 0x0F0F0F0F; return (x * 0x01010101) >> 24; } -#endif -#endif +#endif // __has_builtin(__builtin_popcount) +#endif // _MSC_VER #define MP_FIT_UNSIGNED(bits, value) (((value) & (~0U << (bits))) == 0) #define MP_FIT_SIGNED(bits, value) \ @@ -426,4 +428,93 @@ static inline uint32_t mp_clz_mpi(mp_int_t x) { #endif } +// Overflow-checked operations for long long + +// Integer overflow builtins were added to GCC 5, but __has_builtin only in GCC 10 +// +// Note that the builtins has a defined result when overflow occurs, whereas the custom +// functions below don't update the result if an overflow would occur (to avoid UB). +#define MP_GCC_HAS_BUILTIN_OVERFLOW (__GNUC__ >= 5) + +#if __has_builtin(__builtin_umulll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW +#define mp_mul_ull_overflow __builtin_umulll_overflow +#else +inline static bool mp_mul_ull_overflow(unsigned long long int x, unsigned long long int y, unsigned long long int *res) { + if (y > 0 && x > (ULLONG_MAX / y)) { + return true; // overflow + } + *res = x * y; + return false; +} +#endif + +#if __has_builtin(__builtin_smulll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW +#define mp_mul_ll_overflow __builtin_smulll_overflow +#else +inline static bool mp_mul_ll_overflow(long long int x, long long int y, long long int *res) { + bool overflow; + + // Check for multiply overflow; see CERT INT32-C + if (x > 0) { // x is positive + if (y > 0) { // x and y are positive + overflow = (x > (LLONG_MAX / y)); + } else { // x positive, y nonpositive + overflow = (y < (LLONG_MIN / x)); + } // x positive, y nonpositive + } else { // x is nonpositive + if (y > 0) { // x is nonpositive, y is positive + overflow = (x < (LLONG_MIN / y)); + } else { // x and y are nonpositive + overflow = (x != 0 && y < (LLONG_MAX / x)); + } // End if x and y are nonpositive + } // End if x is nonpositive + + if (!overflow) { + *res = x * y; + } + + return overflow; +} +#endif + +#if __has_builtin(__builtin_saddll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW +#define mp_add_ll_overflow __builtin_saddll_overflow +#else +inline static bool mp_add_ll_overflow(long long int lhs, long long int rhs, long long int *res) { + bool overflow; + + if (rhs > 0) { + overflow = (lhs > LLONG_MAX - rhs); + } else { + overflow = (lhs < LLONG_MIN - rhs); + } + + if (!overflow) { + *res = lhs + rhs; + } + + return overflow; +} +#endif + +#if __has_builtin(__builtin_ssubll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW +#define mp_sub_ll_overflow __builtin_ssubll_overflow +#else +inline static bool mp_sub_ll_overflow(long long int lhs, long long int rhs, long long int *res) { + bool overflow; + + if (rhs > 0) { + overflow = (lhs < LLONG_MIN + rhs); + } else { + overflow = (lhs > LLONG_MAX + rhs); + } + + if (!overflow) { + *res = lhs - rhs; + } + + return overflow; +} +#endif + #endif // MICROPY_INCLUDED_PY_MISC_H |