diff options
author | mrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2017-12-04 02:35:40 +0000 |
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committer | mrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2017-12-04 02:35:40 +0000 |
commit | 9b09cc8a37ca80c7126bfc4ffc39ce9dddcdb1d8 (patch) | |
tree | 077a5bcc275ca50f1588428b384e742f8366f43a /bignum.c | |
parent | 58b3f3654634e86a3d89c74294b8356008ae8597 (diff) |
bignum.c, numeric.c: add Integer#pow(b, m)
This commit is based on the pull-request #1320 created by Makoto Kishimoto.
[Feature #12508] [Feature #11003] [close GH-1320]
* bignum.c (rb_int_powm): Added for Integer#pow(b, m).
* internal.h (rb_int_powm): Declared to refer in numeric.c.
* bignum.c (bary_powm_gmp): Added for Integer#pow(b, m) using GMP.
* bignum.c (int_pow_tmp1): Added for implementing Integer#pow(b, m).
* bignum.c (int_pow_tmp2, int_pow_tmp3): ditto.
* internal.h (rb_num_positive_int_p): Moved from numeric.c for sharing
the definition with bignum.c.
* internal.h (rb_num_negative_int_p, rb_num_compare_with_zero): ditto.
* numeric.c(negative_int_p): Moved to internal.h for sharing the
definition with bignum.c.
* numeric.c (positive_int_p, compare_with_zero): ditto.
* numeric.c (rb_int_odd_p): Exported (renamed from int_odd_p).
* internal.h (rb_int_odd_p): ditto.
* internal.h (HALF_LONG_MSB): Added.
* numeric.c (SQRT_LONG_MAX): Redefined by using HALF_LONG_MSB.
* test/ruby/test_numeric.rb (test_pow): Added for Integer#pow(b, m).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61003 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 216 |
1 files changed, 216 insertions, 0 deletions
@@ -6877,6 +6877,222 @@ rb_big_isqrt(VALUE n) return x; } +#ifdef USE_GMP +static void +bary_powm_gmp(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn, const BDIGIT *mds, size_t mn) +{ + const size_t nails = (sizeof(BDIGIT)-SIZEOF_BDIGIT)*CHAR_BIT; + mpz_t z, x, y, m; + size_t count; + mpz_init(x); + mpz_init(y); + mpz_init(m); + mpz_init(z); + mpz_import(x, xn, -1, sizeof(BDIGIT), 0, nails, xds); + mpz_import(y, yn, -1, sizeof(BDIGIT), 0, nails, yds); + mpz_import(m, mn, -1, sizeof(BDIGIT), 0, nails, mds); + mpz_powm(z, x, y, m); + mpz_export(zds, &count, -1, sizeof(BDIGIT), 0, nails, z); + BDIGITS_ZERO(zds+count, zn-count); + mpz_clear(x); + mpz_clear(y); + mpz_clear(m); + mpz_clear(z); +} +#endif + +static VALUE +int_pow_tmp3(VALUE x, VALUE y, VALUE m, int nega_flg) +{ +#ifdef USE_GMP + VALUE z; + size_t xn, yn, mn, zn; + + if (FIXNUM_P(x)) { + x = rb_int2big(FIX2LONG(x)); + } + if (FIXNUM_P(y)) { + y = rb_int2big(FIX2LONG(y)); + } + assert(RB_BIGNUM_TYPE_P(m)); + xn = BIGNUM_LEN(x); + yn = BIGNUM_LEN(y); + mn = BIGNUM_LEN(m); + zn = mn; + z = bignew(zn, 1); + bary_powm_gmp(BDIGITS(z), zn, BDIGITS(x), xn, BDIGITS(y), yn, BDIGITS(m), mn); + if (nega_flg & BIGNUM_POSITIVE_P(z)) { + z = rb_funcall(z, '-', 1, m); + } + RB_GC_GUARD(x); + RB_GC_GUARD(y); + RB_GC_GUARD(m); + return rb_big_norm(z); +#else + VALUE tmp = LONG2FIX(1L); + long yy; + + for (/*NOP*/; ! FIXNUM_P(y); y = rb_funcall(y, rb_intern(">>"), 1, LONG2FIX(1L))) { + if (RTEST(rb_funcall(y, rb_intern("odd?"), 0))) { + tmp = rb_funcall(tmp, '*', 1, x); + tmp = rb_int_modulo(tmp, m); + } + x = rb_funcall(x, '*', 1, x); + x = rb_int_modulo(x, m); + } + for (yy = FIX2LONG(y); yy; yy >>= 1L) { + if (yy & 1L) { + tmp = rb_funcall(tmp, '*', 1, x); + tmp = rb_int_modulo(tmp, m); + } + x = rb_funcall(x, '*', 1, x); + x = rb_int_modulo(x, m); + } + + if (nega_flg && RTEST(rb_funcall(tmp, rb_intern("positive?"), 0))) { + tmp = rb_funcall(tmp, '-', 1, m); + } + return tmp; +#endif +} + +/* + * Integer#pow + */ + +static VALUE +int_pow_tmp1(VALUE x, VALUE y, long mm, int nega_flg) +{ + long xx = FIX2LONG(x); + long tmp = 1L; + long yy; + + for (/*NOP*/; ! FIXNUM_P(y); y = rb_funcall(y, idGTGT, 1, LONG2FIX(1L))) { + if (RTEST(rb_int_odd_p(y))) { + tmp = (tmp * xx) % mm; + } + xx = (xx * xx) % mm; + } + for (yy = FIX2LONG(y); yy; yy >>= 1L) { + if (yy & 1L) { + tmp = (tmp * xx) % mm; + } + xx = (xx * xx) % mm; + } + + if (nega_flg && tmp) { + tmp -= mm; + } + return LONG2FIX(tmp); +} + +static VALUE +int_pow_tmp2(VALUE x, VALUE y, long mm, int nega_flg) +{ + long tmp = 1L; + long yy; +#ifdef DLONG + DLONG const mmm = mm; + long xx = FIX2LONG(x); + + for (/*NOP*/; ! FIXNUM_P(y); y = rb_funcall(y, idGTGT, 1, LONG2FIX(1L))) { + if (RTEST(rb_int_odd_p(y))) { + tmp = ((DLONG)tmp * (DLONG)xx) % mmm; + } + xx = ((DLONG)xx * (DLONG)xx) % mmm; + } + for (yy = FIX2LONG(y); yy; yy >>= 1L) { + if (yy & 1L) { + tmp = ((DLONG)tmp * (DLONG)xx) % mmm; + } + xx = ((DLONG)xx * (DLONG)xx) % mmm; + } +#else + VALUE const m = LONG2FIX(mm); + VALUE tmp2 = LONG2FIX(tmp); + + for (/*NOP*/; ! FIXNUM_P(y); y = rb_funcall(y, idGTGT, 1, LONG2FIX(1L))) { + if (RTEST(rb_int_odd_p(y))) { + tmp2 = rb_fix_mul_fix(tmp2, x); + tmp2 = rb_int_modulo(tmp2, m); + } + x = rb_fix_mul_fix(x, x); + x = rb_int_modulo(x, m); + } + for (yy = FIX2LONG(y); yy; yy >>= 1L) { + if (yy & 1L) { + tmp2 = rb_fix_mul_fix(tmp2, x); + tmp2 = rb_int_modulo(tmp2, m); + } + x = rb_fix_mul_fix(x, x); + x = rb_int_modulo(x, m); + } + + tmp = FIX2LONG(tmp2); +#endif + if (nega_flg && tmp) { + tmp -= mm; + } + return LONG2FIX(tmp); +} + +/* + * Document-method: Integer#pow + * call-seq: + * integer.pow(integer) -> integer + * integer.pow(integer, integer) -> integer + * + * Returns (modular) exponentiation as: + * + * a.pow(b) #=> same as a**b + * a.pow(b, m) #=> same as (a**b) % m, but doesn't make huge values as temporary + */ +VALUE +rb_int_powm(int const argc, VALUE * const argv, VALUE const num) +{ + rb_check_arity(argc, 1, 2); + + if (argc == 1) { + return rb_funcall(num, rb_intern("**"), 1, argv[0]); + } + else { + VALUE const a = num; + VALUE const b = argv[0]; + VALUE m = argv[1]; + int nega_flg = 0; + if ( ! RB_INTEGER_TYPE_P(b)) { + rb_raise(rb_eTypeError, "Integer#pow() 2nd argument not allowed unless a 1st argument is integer"); + } + if (rb_num_negative_int_p(b)) { + rb_raise(rb_eRangeError, "Integer#pow() 1st argument cannot be negative when 2nd argument specified"); + } + if (!RB_INTEGER_TYPE_P(m)) { + rb_raise(rb_eTypeError, "Integer#pow() 2nd argument not allowed unless all arguments are integers"); + } + + if (rb_num_negative_int_p(m)) { + m = rb_funcall(m, idUMinus, 0); + nega_flg = 1; + } + + if (!rb_num_positive_int_p(m)) { + rb_num_zerodiv(); + } + if (FIXNUM_P(m)) { + long const half_val = (long)HALF_LONG_MSB; + long const mm = FIX2LONG(m); + if (mm <= half_val) { + return int_pow_tmp1(rb_int_modulo(a, m), b, mm, nega_flg); + } else { + return int_pow_tmp2(rb_int_modulo(a, m), b, mm, nega_flg); + } + } else if (RB_TYPE_P(m, T_BIGNUM)) { + return int_pow_tmp3(rb_int_modulo(a, m), b, m, nega_flg); + } + } + UNREACHABLE; +} + /* * Bignum objects hold integers outside the range of * Fixnum. Bignum objects are created |