Message 215690 - Python tracker (original) (raw)

What about using PyVarObject of mp_limb_t and mpn instead of mpz_t?

Addition:

• Check signs and allocate.
• Possibly compare absolute values.
• Call mpn_(add|sub)n and possibly mpn(add|sub)_1 if the integers have different sizes.
• Overhead for small integers: 1 Python->GMP, 1 if.

Subtraction:

• Same as addition

Multiplication:

• Check signs and allocate.
• Call mpn_mul.
• Overhead for small integers: 1 Python->GMP, 2 GMP->GMP, 3 if.

Division:

• Check signs and allocate.
• Call mpn_div_q.
• Overhead for small integers: 1 Python->GMP, 1 GMP->GMP, 1 if, maybe a 3 more ifs in mpn_divrem_1.

Pow:

• Create mpz_t values using MPZ_ROINIT_N(limbs, size) and call mpz_pow(m?). Copy from mpz_limbs_read(result).

• The overhead is after checking if both arguments are integers until going to the right function (mpn_mul -> mpn_mul_n -> mpn_mul_basecase).

Checks for adding integers < 1<<(GMP_NUMB_BITS-1), multiplying < 1<<(GMP_NUMB_BITS/2) and dividing < 1<<GMP_NUMB_BITS can be added.