b739a63eb4
One day, I could not resist the way it was written. I finally started to make the code clean. This changeset is the beginning of a series of housekeeping commits. It is a simple refactoring; split internal.h into files, so that we can divide and concur in the upcoming commits. No lines of codes are either added or removed, except the obvious file headers/footers. The generated binary is identical to the one before.
151 lines
3.8 KiB
C
151 lines
3.8 KiB
C
#ifndef INTERNAL_FIXNUM_H /* -*- C -*- */
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#define INTERNAL_FIXNUM_H
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/**
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* @file
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* @brief Internal header for Fixnums.
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* @author \@shyouhei
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* @copyright This file is a part of the programming language Ruby.
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* Permission is hereby granted, to either redistribute and/or
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* modify this file, provided that the conditions mentioned in the
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* file COPYING are met. Consult the file for details.
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*/
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#if HAVE_LONG_LONG && SIZEOF_LONG * 2 <= SIZEOF_LONG_LONG
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# define DLONG LONG_LONG
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# define DL2NUM(x) LL2NUM(x)
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#elif defined(HAVE_INT128_T)
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# define DLONG int128_t
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# define DL2NUM(x) (RB_FIXABLE(x) ? LONG2FIX(x) : rb_int128t2big(x))
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VALUE rb_int128t2big(int128_t n);
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#endif
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static inline long
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rb_overflowed_fix_to_int(long x)
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{
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return (long)((unsigned long)(x >> 1) ^ (1LU << (SIZEOF_LONG * CHAR_BIT - 1)));
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}
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static inline VALUE
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rb_fix_plus_fix(VALUE x, VALUE y)
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{
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#ifdef HAVE_BUILTIN___BUILTIN_ADD_OVERFLOW
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long lz;
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/* NOTE
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* (1) `LONG2FIX(FIX2LONG(x)+FIX2LONG(y))`
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+ = `((lx*2+1)/2 + (ly*2+1)/2)*2+1`
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+ = `lx*2 + ly*2 + 1`
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+ = `(lx*2+1) + (ly*2+1) - 1`
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+ = `x + y - 1`
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* (2) Fixnum's LSB is always 1.
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* It means you can always run `x - 1` without overflow.
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* (3) Of course `z = x + (y-1)` may overflow.
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* At that time true value is
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* * positive: 0b0 1xxx...1, and z = 0b1xxx...1
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* * nevative: 0b1 0xxx...1, and z = 0b0xxx...1
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* To convert this true value to long,
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* (a) Use arithmetic shift
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* * positive: 0b11xxx...
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* * negative: 0b00xxx...
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* (b) invert MSB
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* * positive: 0b01xxx...
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* * negative: 0b10xxx...
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*/
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if (__builtin_add_overflow((long)x, (long)y-1, &lz)) {
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return rb_int2big(rb_overflowed_fix_to_int(lz));
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}
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else {
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return (VALUE)lz;
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}
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#else
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long lz = FIX2LONG(x) + FIX2LONG(y);
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return LONG2NUM(lz);
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#endif
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}
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static inline VALUE
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rb_fix_minus_fix(VALUE x, VALUE y)
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{
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#ifdef HAVE_BUILTIN___BUILTIN_SUB_OVERFLOW
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long lz;
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if (__builtin_sub_overflow((long)x, (long)y-1, &lz)) {
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return rb_int2big(rb_overflowed_fix_to_int(lz));
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}
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else {
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return (VALUE)lz;
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}
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#else
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long lz = FIX2LONG(x) - FIX2LONG(y);
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return LONG2NUM(lz);
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#endif
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}
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/* arguments must be Fixnum */
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static inline VALUE
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rb_fix_mul_fix(VALUE x, VALUE y)
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{
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long lx = FIX2LONG(x);
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long ly = FIX2LONG(y);
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#ifdef DLONG
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return DL2NUM((DLONG)lx * (DLONG)ly);
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#else
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if (MUL_OVERFLOW_FIXNUM_P(lx, ly)) {
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return rb_big_mul(rb_int2big(lx), rb_int2big(ly));
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}
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else {
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return LONG2FIX(lx * ly);
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}
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#endif
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}
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/*
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* This behaves different from C99 for negative arguments.
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* Note that div may overflow fixnum.
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*/
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static inline void
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rb_fix_divmod_fix(VALUE a, VALUE b, VALUE *divp, VALUE *modp)
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{
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/* assume / and % comply C99.
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* ldiv(3) won't be inlined by GCC and clang.
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* I expect / and % are compiled as single idiv.
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*/
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long x = FIX2LONG(a);
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long y = FIX2LONG(b);
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long div, mod;
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if (x == FIXNUM_MIN && y == -1) {
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if (divp) *divp = LONG2NUM(-FIXNUM_MIN);
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if (modp) *modp = LONG2FIX(0);
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return;
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}
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div = x / y;
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mod = x % y;
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if (y > 0 ? mod < 0 : mod > 0) {
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mod += y;
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div -= 1;
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}
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if (divp) *divp = LONG2FIX(div);
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if (modp) *modp = LONG2FIX(mod);
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}
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/* div() for Ruby
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* This behaves different from C99 for negative arguments.
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*/
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static inline VALUE
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rb_fix_div_fix(VALUE x, VALUE y)
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{
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VALUE div;
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rb_fix_divmod_fix(x, y, &div, NULL);
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return div;
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}
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/* mod() for Ruby
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* This behaves different from C99 for negative arguments.
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*/
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static inline VALUE
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rb_fix_mod_fix(VALUE x, VALUE y)
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{
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VALUE mod;
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rb_fix_divmod_fix(x, y, NULL, &mod);
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return mod;
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}
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#endif /* INTERNAL_FIXNUM_H */
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