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Implement centered-remainder with new integer lib
* libguile/integers.c (scm_integer_centered_remainder_ii) (scm_integer_centered_remainder_iz, scm_integer_centered_remainder_zi) (scm_integer_centered_remainder_zz): New internal functions. * libguile/integers.h: Declare internal functions. * libguile/numbers.c (scm_centered_remainder): Use the new functions. (scm_i_bigint_centered_remainder): Remove helper.
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3 changed files with 127 additions and 117 deletions
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@ -1119,3 +1119,115 @@ scm_integer_centered_quotient_zz (SCM x, SCM y)
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{
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return integer_centered_quotient_zz (scm_bignum (x), scm_bignum (y));
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}
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static SCM
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integer_centered_remainder_zz (struct scm_bignum *x, struct scm_bignum *y)
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{
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mpz_t r, min_r, zx, zy;
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mpz_init (r);
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mpz_init (min_r);
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alias_bignum_to_mpz (x, zx);
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alias_bignum_to_mpz (y, zy);
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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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/* min_r will eventually become -abs(y)/2 */
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mpz_tdiv_q_2exp (min_r, zy, 1);
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/* Arrange for r to initially be non-positive, because that simplifies
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the test to see if it is within the needed bounds. */
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if (mpz_sgn (zy) > 0)
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{
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mpz_cdiv_r (r, zx, zy);
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mpz_neg (min_r, min_r);
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if (mpz_cmp (r, min_r) < 0)
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mpz_add (r, r, zy);
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}
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else
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{
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mpz_fdiv_r (r, zx, zy);
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if (mpz_cmp (r, min_r) < 0)
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mpz_sub (r, r, zy);
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}
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scm_remember_upto_here_2 (x, y);
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mpz_clear (min_r);
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return take_mpz (r);
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}
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SCM
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scm_integer_centered_remainder_ii (scm_t_inum x, scm_t_inum y)
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{
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if (y == 0)
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scm_num_overflow ("centered-remainder");
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scm_t_inum r = x % y;
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if (x > 0)
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{
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if (y > 0)
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{
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if (r >= (y + 1) / 2)
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r -= y;
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}
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else
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{
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if (r >= (1 - y) / 2)
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r += y;
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}
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}
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else
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{
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if (y > 0)
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{
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if (r < -y / 2)
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r += y;
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}
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else
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{
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if (r < y / 2)
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r -= y;
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}
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}
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return SCM_I_MAKINUM (r);
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}
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SCM
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scm_integer_centered_remainder_iz (scm_t_inum x, SCM y)
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{
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return integer_centered_remainder_zz (long_to_bignum (x),
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scm_bignum (y));
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}
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SCM
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scm_integer_centered_remainder_zi (SCM x, scm_t_inum y)
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{
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mpz_t zx;
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alias_bignum_to_mpz (scm_bignum (x), zx);
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if (y == 0)
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scm_num_overflow ("centered-remainder");
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scm_t_inum r;
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/* Arrange for r to initially be non-positive, because that simplifies
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the test to see if it is within the needed bounds. */
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if (y > 0)
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{
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r = - mpz_cdiv_ui (zx, y);
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if (r < -y / 2)
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r += y;
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}
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else
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{
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r = - mpz_cdiv_ui (zx, -y);
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if (r < y / 2)
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r -= y;
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}
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scm_remember_upto_here_1 (x);
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return SCM_I_MAKINUM (r);
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}
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SCM
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scm_integer_centered_remainder_zz (SCM x, SCM y)
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{
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return integer_centered_remainder_zz (scm_bignum (x), scm_bignum (y));
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}
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@ -91,6 +91,11 @@ SCM_INTERNAL SCM scm_integer_centered_quotient_iz (scm_t_inum x, SCM y);
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SCM_INTERNAL SCM scm_integer_centered_quotient_zi (SCM x, scm_t_inum y);
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SCM_INTERNAL SCM scm_integer_centered_quotient_zz (SCM x, SCM y);
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SCM_INTERNAL SCM scm_integer_centered_remainder_ii (scm_t_inum x, scm_t_inum y);
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SCM_INTERNAL SCM scm_integer_centered_remainder_iz (scm_t_inum x, SCM y);
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SCM_INTERNAL SCM scm_integer_centered_remainder_zi (SCM x, scm_t_inum y);
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SCM_INTERNAL SCM scm_integer_centered_remainder_zz (SCM x, SCM y);
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#endif /* SCM_INTEGERS_H */
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@ -2208,7 +2208,6 @@ scm_i_exact_rational_centered_quotient (SCM x, SCM y)
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}
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static SCM scm_i_inexact_centered_remainder (double x, double y);
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static SCM scm_i_bigint_centered_remainder (SCM x, SCM y);
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static SCM scm_i_exact_rational_centered_remainder (SCM x, SCM y);
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SCM_PRIMITIVE_GENERIC (scm_centered_remainder, "centered-remainder", 2, 0, 0,
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@ -2227,54 +2226,16 @@ SCM_PRIMITIVE_GENERIC (scm_centered_remainder, "centered-remainder", 2, 0, 0,
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"@end lisp")
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#define FUNC_NAME s_scm_centered_remainder
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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_centered_remainder);
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else
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{
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scm_t_inum rr = xx % yy;
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if (SCM_LIKELY (xx > 0))
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{
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if (SCM_LIKELY (yy > 0))
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{
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if (rr >= (yy + 1) / 2)
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rr -= yy;
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}
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else
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{
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if (rr >= (1 - yy) / 2)
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rr += yy;
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}
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}
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else
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{
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if (SCM_LIKELY (yy > 0))
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{
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if (rr < -yy / 2)
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rr += yy;
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}
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else
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{
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if (rr < yy / 2)
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rr -= yy;
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}
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}
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return 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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return scm_integer_centered_remainder_ii (SCM_I_INUM (x),
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SCM_I_INUM (y));
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else if (SCM_BIGP (y))
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{
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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_centered_remainder */
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return scm_i_bigint_centered_remainder (scm_i_long2big (xx), y);
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}
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return scm_integer_centered_remainder_iz (SCM_I_INUM (x), y);
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else if (SCM_REALP (y))
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return scm_i_inexact_centered_remainder (xx, SCM_REAL_VALUE (y));
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return scm_i_inexact_centered_remainder (SCM_I_INUM (x),
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SCM_REAL_VALUE (y));
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else if (SCM_FRACTIONP (y))
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return scm_i_exact_rational_centered_remainder (x, y);
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else
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@ -2283,36 +2244,10 @@ SCM_PRIMITIVE_GENERIC (scm_centered_remainder, "centered-remainder", 2, 0, 0,
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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_centered_remainder);
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else
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{
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scm_t_inum rr;
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/* Arrange for rr to initially be non-positive,
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because that simplifies the test to see
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if it is within the needed bounds. */
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if (yy > 0)
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{
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rr = - mpz_cdiv_ui (SCM_I_BIG_MPZ (x), yy);
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scm_remember_upto_here_1 (x);
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if (rr < -yy / 2)
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rr += yy;
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}
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else
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{
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rr = - mpz_cdiv_ui (SCM_I_BIG_MPZ (x), -yy);
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scm_remember_upto_here_1 (x);
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if (rr < yy / 2)
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rr -= yy;
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}
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return 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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return scm_integer_centered_remainder_zi (x, SCM_I_INUM (y));
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else if (SCM_BIGP (y))
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return scm_i_bigint_centered_remainder (x, y);
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return scm_integer_centered_remainder_zz (x, y);
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else if (SCM_REALP (y))
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return scm_i_inexact_centered_remainder
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(scm_i_big2dbl (x), SCM_REAL_VALUE (y));
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@ -2372,48 +2307,6 @@ scm_i_inexact_centered_remainder (double x, double y)
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return scm_i_from_double (x - q * y);
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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 SCM
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scm_i_bigint_centered_remainder (SCM x, SCM y)
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{
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SCM r, min_r;
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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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r = scm_i_mkbig ();
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/* min_r will eventually become -abs(y)/2 */
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min_r = scm_i_mkbig ();
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mpz_tdiv_q_2exp (SCM_I_BIG_MPZ (min_r),
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SCM_I_BIG_MPZ (y), 1);
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/* Arrange for rr to initially be non-positive,
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because that simplifies the test to see
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if it is within the needed bounds. */
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if (mpz_sgn (SCM_I_BIG_MPZ (y)) > 0)
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{
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mpz_cdiv_r (SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y));
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mpz_neg (SCM_I_BIG_MPZ (min_r), SCM_I_BIG_MPZ (min_r));
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if (mpz_cmp (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (min_r)) < 0)
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mpz_add (SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (y));
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}
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else
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{
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mpz_fdiv_r (SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y));
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if (mpz_cmp (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (min_r)) < 0)
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mpz_sub (SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (r),
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SCM_I_BIG_MPZ (y));
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}
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scm_remember_upto_here_2 (x, y);
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return scm_i_normbig (r);
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}
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static SCM
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scm_i_exact_rational_centered_remainder (SCM x, SCM y)
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{
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