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Diffstat (limited to 'internal/fixnum.h')
| -rw-r--r-- | internal/fixnum.h | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/internal/fixnum.h b/internal/fixnum.h new file mode 100644 index 0000000000..b78e31460e --- /dev/null +++ b/internal/fixnum.h @@ -0,0 +1,185 @@ +#ifndef INTERNAL_FIXNUM_H /*-*-C-*-vi:se ft=c:*/ +#define INTERNAL_FIXNUM_H +/** + * @author Ruby developers <ruby-core@ruby-lang.org> + * @copyright This file is a part of the programming language Ruby. + * Permission is hereby granted, to either redistribute and/or + * modify this file, provided that the conditions mentioned in the + * file COPYING are met. Consult the file for details. + * @brief Internal header for Fixnums. + */ +#include "ruby/internal/config.h" /* for HAVE_LONG_LONG */ +#include <limits.h> /* for CHAR_BIT */ +#include "internal/bits.h" /* for MUL_OVERFLOW_FIXNUM_P */ +#include "internal/compilers.h" /* for __has_builtin */ +#include "ruby/internal/stdbool.h" /* for bool */ +#include "ruby/intern.h" /* for rb_big_mul */ +#include "ruby/ruby.h" /* for RB_FIXABLE */ + +#if HAVE_LONG_LONG && SIZEOF_LONG * 2 <= SIZEOF_LONG_LONG +# define DLONG LONG_LONG +# define DL2NUM(x) LL2NUM(x) +#elif defined(HAVE_INT128_T) && !(defined(__OpenBSD__) && defined(__mips64__)) +# define DLONG int128_t +# define DL2NUM(x) (RB_FIXABLE(x) ? LONG2FIX(x) : rb_int128t2big(x)) +VALUE rb_int128t2big(int128_t n); /* in bignum.c */ +#endif + +static inline long rb_overflowed_fix_to_int(long x); +static inline VALUE rb_fix_plus_fix(VALUE x, VALUE y); +static inline VALUE rb_fix_minus_fix(VALUE x, VALUE y); +static inline VALUE rb_fix_mul_fix(VALUE x, VALUE y); +static inline void rb_fix_divmod_fix(VALUE x, VALUE y, VALUE *divp, VALUE *modp); +static inline VALUE rb_fix_div_fix(VALUE x, VALUE y); +static inline VALUE rb_fix_mod_fix(VALUE x, VALUE y); +static inline bool FIXNUM_POSITIVE_P(VALUE num); +static inline bool FIXNUM_NEGATIVE_P(VALUE num); +static inline bool FIXNUM_ZERO_P(VALUE num); + +static inline long +rb_overflowed_fix_to_int(long x) +{ + return (long)((unsigned long)(x >> 1) ^ (1LU << (SIZEOF_LONG * CHAR_BIT - 1))); +} + +static inline VALUE +rb_fix_plus_fix(VALUE x, VALUE y) +{ +#if !__has_builtin(__builtin_add_overflow) + long lz = FIX2LONG(x) + FIX2LONG(y); + return LONG2NUM(lz); +#else + long lz; + /* NOTE + * (1) `LONG2FIX(FIX2LONG(x)+FIX2LONG(y))` + + = `((lx*2+1)/2 + (ly*2+1)/2)*2+1` + + = `lx*2 + ly*2 + 1` + + = `(lx*2+1) + (ly*2+1) - 1` + + = `x + y - 1` + * (2) Fixnum's LSB is always 1. + * It means you can always run `x - 1` without overflow. + * (3) Of course `z = x + (y-1)` may overflow. + * At that time true value is + * * positive: 0b0 1xxx...1, and z = 0b1xxx...1 + * * negative: 0b1 0xxx...1, and z = 0b0xxx...1 + * To convert this true value to long, + * (a) Use arithmetic shift + * * positive: 0b11xxx... + * * negative: 0b00xxx... + * (b) invert MSB + * * positive: 0b01xxx... + * * negative: 0b10xxx... + */ + if (__builtin_add_overflow((long)x, (long)y-1, &lz)) { + return rb_int2big(rb_overflowed_fix_to_int(lz)); + } + else { + return (VALUE)lz; + } +#endif +} + +static inline VALUE +rb_fix_minus_fix(VALUE x, VALUE y) +{ +#if !__has_builtin(__builtin_sub_overflow) + long lz = FIX2LONG(x) - FIX2LONG(y); + return LONG2NUM(lz); +#else + long lz; + if (__builtin_sub_overflow((long)x, (long)y-1, &lz)) { + return rb_int2big(rb_overflowed_fix_to_int(lz)); + } + else { + return (VALUE)lz; + } +#endif +} + +/* arguments must be Fixnum */ +static inline VALUE +rb_fix_mul_fix(VALUE x, VALUE y) +{ + long lx = FIX2LONG(x); + long ly = FIX2LONG(y); +#ifdef DLONG + return DL2NUM((DLONG)lx * (DLONG)ly); +#else + if (MUL_OVERFLOW_FIXNUM_P(lx, ly)) { + return rb_big_mul(rb_int2big(lx), rb_int2big(ly)); + } + else { + return LONG2FIX(lx * ly); + } +#endif +} + +/* + * This behaves different from C99 for negative arguments. + * Note that div may overflow fixnum. + */ +static inline void +rb_fix_divmod_fix(VALUE a, VALUE b, VALUE *divp, VALUE *modp) +{ + /* assume / and % comply C99. + * ldiv(3) won't be inlined by GCC and clang. + * I expect / and % are compiled as single idiv. + */ + long x = FIX2LONG(a); + long y = FIX2LONG(b); + long div, mod; + if (x == FIXNUM_MIN && y == -1) { + if (divp) *divp = LONG2NUM(-FIXNUM_MIN); + if (modp) *modp = LONG2FIX(0); + return; + } + div = x / y; + mod = x % y; + if (y > 0 ? mod < 0 : mod > 0) { + mod += y; + div -= 1; + } + if (divp) *divp = LONG2FIX(div); + if (modp) *modp = LONG2FIX(mod); +} + +/* div() for Ruby + * This behaves different from C99 for negative arguments. + */ +static inline VALUE +rb_fix_div_fix(VALUE x, VALUE y) +{ + VALUE div; + rb_fix_divmod_fix(x, y, &div, NULL); + return div; +} + +/* mod() for Ruby + * This behaves different from C99 for negative arguments. + */ +static inline VALUE +rb_fix_mod_fix(VALUE x, VALUE y) +{ + VALUE mod; + rb_fix_divmod_fix(x, y, NULL, &mod); + return mod; +} + +static inline bool +FIXNUM_POSITIVE_P(VALUE num) +{ + return (SIGNED_VALUE)num > (SIGNED_VALUE)INT2FIX(0); +} + +static inline bool +FIXNUM_NEGATIVE_P(VALUE num) +{ + return (SIGNED_VALUE)num < 0; +} + +static inline bool +FIXNUM_ZERO_P(VALUE num) +{ + return num == INT2FIX(0); +} +#endif /* INTERNAL_FIXNUM_H */ |