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Implement round-divide with new integer lib
* libguile/integers.c (scm_integer_round_divide_ii) (scm_integer_round_divide_iz, scm_integer_round_divide_zi) (scm_integer_round_divide_zz): New internal functions. (integer_round_divide_zz): New helper. * libguile/integers.h: Declare internal functions. * libguile/numbers.c (scm_round_divide): Use the new functions. (scm_i_bigint_round_divide): Remove unused helper.
This commit is contained in:
Andy Wingo
parent
b114642640
commit
025c7c8045
3 changed files with 140 additions and 123 deletions
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@ -1619,3 +1619,126 @@ scm_integer_round_remainder_zz (SCM x, SCM y)
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{
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return integer_round_remainder_zz (scm_bignum (x), scm_bignum (y));
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}
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static void
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integer_round_divide_zz (struct scm_bignum *x, struct scm_bignum *y,
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SCM *qp, SCM *rp)
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{
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mpz_t q, r, r2, zx, zy;
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int cmp, needs_adjustment;
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/* Note that x might be small enough to fit into a fixnum, so we must
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not let it escape into the wild */
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mpz_init (q);
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mpz_init (r);
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mpz_init (r2);
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alias_bignum_to_mpz (x, zx);
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alias_bignum_to_mpz (y, zy);
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mpz_fdiv_qr (q, r, zx, zy);
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scm_remember_upto_here_1 (x);
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mpz_mul_2exp (r2, r, 1); /* r2 = 2*r */
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cmp = mpz_cmpabs (r2, zy);
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if (mpz_odd_p (q))
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needs_adjustment = (cmp >= 0);
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else
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needs_adjustment = (cmp > 0);
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if (needs_adjustment)
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{
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mpz_add_ui (q, q, 1);
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mpz_sub (r, r, zy);
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}
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scm_remember_upto_here_1 (y);
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mpz_clear (r2);
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*qp = take_mpz (q);
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*rp = take_mpz (r);
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}
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void
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scm_integer_round_divide_ii (scm_t_inum x, scm_t_inum y, SCM *qp, SCM *rp)
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{
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if (y == 0)
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scm_num_overflow ("round-divide");
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scm_t_inum q = x / y;
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scm_t_inum r = x % y;
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scm_t_inum ay = y;
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scm_t_inum r2 = 2 * r;
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if (y < 0)
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{
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ay = -ay;
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r2 = -r2;
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}
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if (q & 1L)
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{
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if (r2 >= ay)
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{ q++; r -= y; }
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else if (r2 <= -ay)
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{ q--; r += y; }
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}
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else
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{
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if (r2 > ay)
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{ q++; r -= y; }
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else if (r2 < -ay)
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{ q--; r += y; }
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}
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*qp = long_to_scm (q);
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*rp = SCM_I_MAKINUM (r);
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}
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void
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scm_integer_round_divide_iz (scm_t_inum x, SCM y, SCM *qp, SCM *rp)
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{
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integer_round_divide_zz (long_to_bignum (x), scm_bignum (y), qp, rp);
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}
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void
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scm_integer_round_divide_zi (SCM x, scm_t_inum y, SCM *qp, SCM *rp)
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{
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if (y == 0)
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scm_num_overflow ("round-divide");
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mpz_t q, zx;
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mpz_init (q);
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alias_bignum_to_mpz (scm_bignum (x), zx);
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scm_t_inum r;
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int needs_adjustment;
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if (y > 0)
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{
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r = mpz_fdiv_q_ui (q, zx, y);
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if (mpz_odd_p (q))
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needs_adjustment = (2*r >= y);
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else
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needs_adjustment = (2*r > y);
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}
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else
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{
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r = - mpz_cdiv_q_ui (q, zx, -y);
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mpz_neg (q, q);
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if (mpz_odd_p (q))
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needs_adjustment = (2*r <= y);
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else
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needs_adjustment = (2*r < y);
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}
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scm_remember_upto_here_1 (x);
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if (needs_adjustment)
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{
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mpz_add_ui (q, q, 1);
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r -= y;
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}
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*qp = take_mpz (q);
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*rp = SCM_I_MAKINUM (r);
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}
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void
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scm_integer_round_divide_zz (SCM x, SCM y, SCM *qp, SCM *rp)
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{
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integer_round_divide_zz (scm_bignum (x), scm_bignum (y), qp, rp);
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}
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@ -115,6 +115,15 @@ SCM_INTERNAL SCM scm_integer_round_remainder_iz (scm_t_inum x, SCM y);
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SCM_INTERNAL SCM scm_integer_round_remainder_zi (SCM x, scm_t_inum y);
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SCM_INTERNAL SCM scm_integer_round_remainder_zz (SCM x, SCM y);
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SCM_INTERNAL void scm_integer_round_divide_ii (scm_t_inum x, scm_t_inum y,
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SCM *qp, SCM *rp);
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SCM_INTERNAL void scm_integer_round_divide_iz (scm_t_inum x, SCM y,
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SCM *qp, SCM *rp);
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SCM_INTERNAL void scm_integer_round_divide_zi (SCM x, scm_t_inum y,
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SCM *qp, SCM *rp);
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SCM_INTERNAL void scm_integer_round_divide_zz (SCM x, SCM y,
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SCM *qp, SCM *rp);
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#endif /* SCM_INTEGERS_H */
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@ -2644,7 +2644,6 @@ scm_i_exact_rational_round_remainder (SCM x, SCM y)
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static void scm_i_inexact_round_divide (double x, double y, SCM *qp, SCM *rp);
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static void scm_i_bigint_round_divide (SCM x, SCM y, SCM *qp, SCM *rp);
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static void scm_i_exact_rational_round_divide (SCM x, SCM y, SCM *qp, SCM *rp);
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SCM_PRIMITIVE_GENERIC (scm_i_round_divide, "round/", 2, 0, 0,
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@ -2679,54 +2678,14 @@ SCM_PRIMITIVE_GENERIC (scm_i_round_divide, "round/", 2, 0, 0,
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void
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scm_round_divide (SCM x, SCM y, SCM *qp, SCM *rp)
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{
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if (SCM_LIKELY (SCM_I_INUMP (x)))
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if (SCM_I_INUMP (x))
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{
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scm_t_inum xx = SCM_I_INUM (x);
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if (SCM_LIKELY (SCM_I_INUMP (y)))
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{
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scm_t_inum yy = SCM_I_INUM (y);
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if (SCM_UNLIKELY (yy == 0))
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scm_num_overflow (s_scm_round_divide);
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else
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{
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scm_t_inum qq = xx / yy;
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scm_t_inum rr = xx % yy;
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scm_t_inum ay = yy;
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scm_t_inum r2 = 2 * rr;
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if (SCM_LIKELY (yy < 0))
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{
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ay = -ay;
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r2 = -r2;
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}
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if (qq & 1L)
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{
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if (r2 >= ay)
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{ qq++; rr -= yy; }
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else if (r2 <= -ay)
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{ qq--; rr += yy; }
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}
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else
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{
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if (r2 > ay)
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{ qq++; rr -= yy; }
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else if (r2 < -ay)
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{ qq--; rr += yy; }
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}
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if (SCM_LIKELY (SCM_FIXABLE (qq)))
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*qp = SCM_I_MAKINUM (qq);
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else
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*qp = scm_i_inum2big (qq);
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*rp = SCM_I_MAKINUM (rr);
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}
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}
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if (SCM_I_INUMP (y))
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scm_integer_round_divide_ii (SCM_I_INUM (x), SCM_I_INUM (y), qp, rp);
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else if (SCM_BIGP (y))
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/* Pass a denormalized bignum version of x (even though it
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can fit in a fixnum) to scm_i_bigint_round_divide */
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scm_i_bigint_round_divide (scm_i_long2big (SCM_I_INUM (x)), y, qp, rp);
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scm_integer_round_divide_iz (SCM_I_INUM (x), y, qp, rp);
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else if (SCM_REALP (y))
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scm_i_inexact_round_divide (xx, SCM_REAL_VALUE (y), qp, rp);
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scm_i_inexact_round_divide (SCM_I_INUM (x), SCM_REAL_VALUE (y), qp, rp);
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else if (SCM_FRACTIONP (y))
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scm_i_exact_rational_round_divide (x, y, qp, rp);
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else
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@ -2735,48 +2694,10 @@ scm_round_divide (SCM x, SCM y, SCM *qp, SCM *rp)
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}
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else if (SCM_BIGP (x))
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{
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if (SCM_LIKELY (SCM_I_INUMP (y)))
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{
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scm_t_inum yy = SCM_I_INUM (y);
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if (SCM_UNLIKELY (yy == 0))
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scm_num_overflow (s_scm_round_divide);
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else
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{
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SCM q = scm_i_mkbig ();
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scm_t_inum rr;
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int needs_adjustment;
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if (yy > 0)
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{
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rr = mpz_fdiv_q_ui (SCM_I_BIG_MPZ (q),
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SCM_I_BIG_MPZ (x), yy);
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if (mpz_odd_p (SCM_I_BIG_MPZ (q)))
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needs_adjustment = (2*rr >= yy);
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else
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needs_adjustment = (2*rr > yy);
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}
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else
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{
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rr = - mpz_cdiv_q_ui (SCM_I_BIG_MPZ (q),
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SCM_I_BIG_MPZ (x), -yy);
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mpz_neg (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q));
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if (mpz_odd_p (SCM_I_BIG_MPZ (q)))
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needs_adjustment = (2*rr <= yy);
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else
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needs_adjustment = (2*rr < yy);
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}
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scm_remember_upto_here_1 (x);
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if (needs_adjustment)
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{
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mpz_add_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q), 1);
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rr -= yy;
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}
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*qp = scm_i_normbig (q);
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*rp = SCM_I_MAKINUM (rr);
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}
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}
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if (SCM_I_INUMP (y))
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scm_integer_round_divide_zi (x, SCM_I_INUM (y), qp, rp);
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else if (SCM_BIGP (y))
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scm_i_bigint_round_divide (x, y, qp, rp);
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scm_integer_round_divide_zz (x, y, qp, rp);
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else if (SCM_REALP (y))
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scm_i_inexact_round_divide (scm_i_big2dbl (x), SCM_REAL_VALUE (y),
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qp, rp);
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@ -2826,42 +2747,6 @@ scm_i_inexact_round_divide (double x, double y, SCM *qp, SCM *rp)
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}
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}
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/* Assumes that both x and y are bigints, though
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x might be able to fit into a fixnum. */
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static void
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scm_i_bigint_round_divide (SCM x, SCM y, SCM *qp, SCM *rp)
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{
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SCM q, r, r2;
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int cmp, needs_adjustment;
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/* Note that x might be small enough to fit into a
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fixnum, so we must not let it escape into the wild */
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q = scm_i_mkbig ();
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r = scm_i_mkbig ();
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r2 = scm_i_mkbig ();
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mpz_fdiv_qr (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y));
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scm_remember_upto_here_1 (x);
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mpz_mul_2exp (SCM_I_BIG_MPZ (r2), SCM_I_BIG_MPZ (r), 1); /* r2 = 2*r */
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cmp = mpz_cmpabs (SCM_I_BIG_MPZ (r2), SCM_I_BIG_MPZ (y));
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if (mpz_odd_p (SCM_I_BIG_MPZ (q)))
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needs_adjustment = (cmp >= 0);
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else
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needs_adjustment = (cmp > 0);
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if (needs_adjustment)
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{
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mpz_add_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q), 1);
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mpz_sub (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (y));
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}
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scm_remember_upto_here_2 (r2, y);
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*qp = scm_i_normbig (q);
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*rp = scm_i_normbig (r);
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}
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static void
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scm_i_exact_rational_round_divide (SCM x, SCM y, SCM *qp, SCM *rp)
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{
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