diff --git a/libguile/integers.c b/libguile/integers.c index cfc71a8c8..102278e44 100644 --- a/libguile/integers.c +++ b/libguile/integers.c @@ -1231,3 +1231,136 @@ scm_integer_centered_remainder_zz (SCM x, SCM y) { return integer_centered_remainder_zz (scm_bignum (x), scm_bignum (y)); } + +static void +integer_centered_divide_zz (struct scm_bignum *x, struct scm_bignum *y, + SCM *qp, SCM *rp) +{ + mpz_t q, r, min_r, zx, zy; + mpz_init (q); + mpz_init (r); + mpz_init (min_r); + alias_bignum_to_mpz (x, zx); + alias_bignum_to_mpz (y, zy); + + /* Note that x might be small enough to fit into a fixnum, so we must + not let it escape into the wild */ + + /* min_r will eventually become -abs(y/2) */ + mpz_tdiv_q_2exp (min_r, zy, 1); + + /* Arrange for rr to initially be non-positive, because that + simplifies the test to see if it is within the needed bounds. */ + if (mpz_sgn (zy) > 0) + { + mpz_cdiv_qr (q, r, zx, zy); + mpz_neg (min_r, min_r); + if (mpz_cmp (r, min_r) < 0) + { + mpz_sub_ui (q, q, 1); + mpz_add (r, r, zy); + } + } + else + { + mpz_fdiv_qr (q, r, zx, zy); + if (mpz_cmp (r, min_r) < 0) + { + mpz_add_ui (q, q, 1); + mpz_sub (r, r, zy); + } + } + scm_remember_upto_here_2 (x, y); + mpz_clear (min_r); + *qp = take_mpz (q); + *rp = take_mpz (r); +} + +void +scm_integer_centered_divide_ii (scm_t_inum x, scm_t_inum y, SCM *qp, SCM *rp) +{ + if (y == 0) + scm_num_overflow ("centered-divide"); + + scm_t_inum q = x / y; + scm_t_inum r = x % y; + if (x > 0) + { + if (y > 0) + { + if (r >= (y + 1) / 2) + { q++; r -= y; } + } + else + { + if (r >= (1 - y) / 2) + { q--; r += y; } + } + } + else + { + if (y > 0) + { + if (r < -y / 2) + { q--; r += y; } + } + else + { + if (r < y / 2) + { q++; r -= y; } + } + } + *qp = long_to_scm (q); + *rp = SCM_I_MAKINUM (r); +} + +void +scm_integer_centered_divide_iz (scm_t_inum x, SCM y, SCM *qp, SCM *rp) +{ + integer_centered_divide_zz (long_to_bignum (x), scm_bignum (y), qp, rp); +} + +void +scm_integer_centered_divide_zi (SCM x, scm_t_inum y, SCM *qp, SCM *rp) +{ + if (y == 0) + scm_num_overflow ("centered-divide"); + + mpz_t q, zx; + mpz_init (q); + alias_bignum_to_mpz (scm_bignum (x), zx); + scm_t_inum r; + + /* Arrange for r to initially be non-positive, because that + simplifies the test to see if it is within the needed bounds. */ + + if (y > 0) + { + r = - mpz_cdiv_q_ui (q, zx, y); + if (r < -y / 2) + { + mpz_sub_ui (q, q, 1); + r += y; + } + } + else + { + r = - mpz_cdiv_q_ui (q, zx, -y); + mpz_neg (q, q); + if (r < y / 2) + { + mpz_add_ui (q, q, 1); + r -= y; + } + } + scm_remember_upto_here_1 (x); + *qp = take_mpz (q); + *rp = SCM_I_MAKINUM (r); +} + +void +scm_integer_centered_divide_zz (SCM x, SCM y, SCM *qp, SCM *rp) +{ + integer_centered_divide_zz (scm_bignum (x), scm_bignum (y), qp, rp); +} + diff --git a/libguile/integers.h b/libguile/integers.h index 13c69e374..f941eefc6 100644 --- a/libguile/integers.h +++ b/libguile/integers.h @@ -96,6 +96,15 @@ SCM_INTERNAL SCM scm_integer_centered_remainder_iz (scm_t_inum x, SCM y); SCM_INTERNAL SCM scm_integer_centered_remainder_zi (SCM x, scm_t_inum y); SCM_INTERNAL SCM scm_integer_centered_remainder_zz (SCM x, SCM y); +SCM_INTERNAL void scm_integer_centered_divide_ii (scm_t_inum x, scm_t_inum y, + SCM *qp, SCM *rp); +SCM_INTERNAL void scm_integer_centered_divide_iz (scm_t_inum x, SCM y, + SCM *qp, SCM *rp); +SCM_INTERNAL void scm_integer_centered_divide_zi (SCM x, scm_t_inum y, + SCM *qp, SCM *rp); +SCM_INTERNAL void scm_integer_centered_divide_zz (SCM x, SCM y, + SCM *qp, SCM *rp); + #endif /* SCM_INTEGERS_H */ diff --git a/libguile/numbers.c b/libguile/numbers.c index 1c915b75a..284d17fd4 100644 --- a/libguile/numbers.c +++ b/libguile/numbers.c @@ -2320,7 +2320,6 @@ scm_i_exact_rational_centered_remainder (SCM x, SCM y) static void scm_i_inexact_centered_divide (double x, double y, SCM *qp, SCM *rp); -static void scm_i_bigint_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp); static void scm_i_exact_rational_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp); @@ -2352,57 +2351,15 @@ SCM_PRIMITIVE_GENERIC (scm_i_centered_divide, "centered/", 2, 0, 0, void scm_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp) { - if (SCM_LIKELY (SCM_I_INUMP (x))) + if (SCM_I_INUMP (x)) { - scm_t_inum xx = SCM_I_INUM (x); - if (SCM_LIKELY (SCM_I_INUMP (y))) - { - scm_t_inum yy = SCM_I_INUM (y); - if (SCM_UNLIKELY (yy == 0)) - scm_num_overflow (s_scm_centered_divide); - else - { - scm_t_inum qq = xx / yy; - scm_t_inum rr = xx % yy; - if (SCM_LIKELY (xx > 0)) - { - if (SCM_LIKELY (yy > 0)) - { - if (rr >= (yy + 1) / 2) - { qq++; rr -= yy; } - } - else - { - if (rr >= (1 - yy) / 2) - { qq--; rr += yy; } - } - } - else - { - if (SCM_LIKELY (yy > 0)) - { - if (rr < -yy / 2) - { qq--; rr += yy; } - } - else - { - if (rr < yy / 2) - { qq++; rr -= yy; } - } - } - if (SCM_LIKELY (SCM_FIXABLE (qq))) - *qp = SCM_I_MAKINUM (qq); - else - *qp = scm_i_inum2big (qq); - *rp = SCM_I_MAKINUM (rr); - } - } + if (SCM_I_INUMP (y)) + scm_integer_centered_divide_ii (SCM_I_INUM (x), SCM_I_INUM (y), qp, rp); else if (SCM_BIGP (y)) - /* Pass a denormalized bignum version of x (even though it - can fit in a fixnum) to scm_i_bigint_centered_divide */ - scm_i_bigint_centered_divide (scm_i_long2big (xx), y, qp, rp); + scm_integer_centered_divide_iz (SCM_I_INUM (x), y, qp, rp); else if (SCM_REALP (y)) - scm_i_inexact_centered_divide (xx, SCM_REAL_VALUE (y), qp, rp); + scm_i_inexact_centered_divide (SCM_I_INUM (x), SCM_REAL_VALUE (y), + qp, rp); else if (SCM_FRACTIONP (y)) scm_i_exact_rational_centered_divide (x, y, qp, rp); else @@ -2411,49 +2368,10 @@ scm_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp) } else if (SCM_BIGP (x)) { - if (SCM_LIKELY (SCM_I_INUMP (y))) - { - scm_t_inum yy = SCM_I_INUM (y); - if (SCM_UNLIKELY (yy == 0)) - scm_num_overflow (s_scm_centered_divide); - else - { - SCM q = scm_i_mkbig (); - scm_t_inum rr; - /* Arrange for rr to initially be non-positive, - because that simplifies the test to see - if it is within the needed bounds. */ - if (yy > 0) - { - rr = - mpz_cdiv_q_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (x), yy); - scm_remember_upto_here_1 (x); - if (rr < -yy / 2) - { - mpz_sub_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (q), 1); - rr += yy; - } - } - else - { - rr = - mpz_cdiv_q_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (x), -yy); - scm_remember_upto_here_1 (x); - mpz_neg (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q)); - if (rr < yy / 2) - { - mpz_add_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (q), 1); - rr -= yy; - } - } - *qp = scm_i_normbig (q); - *rp = SCM_I_MAKINUM (rr); - } - } + if (SCM_I_INUMP (y)) + scm_integer_centered_divide_zi (x, SCM_I_INUM (y), qp, rp); else if (SCM_BIGP (y)) - scm_i_bigint_centered_divide (x, y, qp, rp); + scm_integer_centered_divide_zz (x, y, qp, rp); else if (SCM_REALP (y)) scm_i_inexact_centered_divide (scm_i_big2dbl (x), SCM_REAL_VALUE (y), qp, rp); @@ -2507,58 +2425,6 @@ scm_i_inexact_centered_divide (double x, double y, SCM *qp, SCM *rp) *rp = scm_i_from_double (r); } -/* Assumes that both x and y are bigints, though - x might be able to fit into a fixnum. */ -static void -scm_i_bigint_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp) -{ - SCM q, r, min_r; - - /* Note that x might be small enough to fit into a - fixnum, so we must not let it escape into the wild */ - q = scm_i_mkbig (); - r = scm_i_mkbig (); - - /* min_r will eventually become -abs(y/2) */ - min_r = scm_i_mkbig (); - mpz_tdiv_q_2exp (SCM_I_BIG_MPZ (min_r), - SCM_I_BIG_MPZ (y), 1); - - /* Arrange for rr to initially be non-positive, - because that simplifies the test to see - if it is within the needed bounds. */ - if (mpz_sgn (SCM_I_BIG_MPZ (y)) > 0) - { - mpz_cdiv_qr (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y)); - mpz_neg (SCM_I_BIG_MPZ (min_r), SCM_I_BIG_MPZ (min_r)); - if (mpz_cmp (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (min_r)) < 0) - { - mpz_sub_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (q), 1); - mpz_add (SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (y)); - } - } - else - { - mpz_fdiv_qr (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y)); - if (mpz_cmp (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (min_r)) < 0) - { - mpz_add_ui (SCM_I_BIG_MPZ (q), - SCM_I_BIG_MPZ (q), 1); - mpz_sub (SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (r), - SCM_I_BIG_MPZ (y)); - } - } - scm_remember_upto_here_2 (x, y); - *qp = scm_i_normbig (q); - *rp = scm_i_normbig (r); -} - static void scm_i_exact_rational_centered_divide (SCM x, SCM y, SCM *qp, SCM *rp) {