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Diffstat (limited to 'ext/bcmath/libbcmath/src/recmul.c')
| -rw-r--r-- | ext/bcmath/libbcmath/src/recmul.c | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/ext/bcmath/libbcmath/src/recmul.c b/ext/bcmath/libbcmath/src/recmul.c new file mode 100644 index 0000000..c31d09d --- /dev/null +++ b/ext/bcmath/libbcmath/src/recmul.c @@ -0,0 +1,306 @@ +/* recmul.c: bcmath library file. */ +/* + Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc. + Copyright (C) 2000 Philip A. Nelson + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. (COPYING.LIB) + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, write to: + + The Free Software Foundation, Inc. + 59 Temple Place, Suite 330 + Boston, MA 02111-1307 USA. + + You may contact the author by: + e-mail: philnelson@acm.org + us-mail: Philip A. Nelson + Computer Science Department, 9062 + Western Washington University + Bellingham, WA 98226-9062 + +*************************************************************************/ + +#include <config.h> +#include <stdio.h> +#include <assert.h> +#include <stdlib.h> +#include <ctype.h> +#include <stdarg.h> +#include "bcmath.h" +#include "private.h" + +/* Recursive vs non-recursive multiply crossover ranges. */ +#if defined(MULDIGITS) +#include "muldigits.h" +#else +#define MUL_BASE_DIGITS 80 +#endif + +int mul_base_digits = MUL_BASE_DIGITS; +#define MUL_SMALL_DIGITS mul_base_digits/4 + +/* Multiply utility routines */ + +static bc_num +new_sub_num (length, scale, value) + int length, scale; + char *value; +{ + bc_num temp; + +#ifdef SANDER_0 + if (_bc_Free_list != NULL) { + temp = _bc_Free_list; + _bc_Free_list = temp->n_next; + } else { +#endif + temp = (bc_num) emalloc (sizeof(bc_struct)); +#ifdef SANDER_0 + if (temp == NULL) bc_out_of_memory (); + } +#endif + temp->n_sign = PLUS; + temp->n_len = length; + temp->n_scale = scale; + temp->n_refs = 1; + temp->n_ptr = NULL; + temp->n_value = value; + return temp; +} + +static void +_bc_simp_mul (bc_num n1, int n1len, bc_num n2, int n2len, bc_num *prod, + int full_scale) +{ + char *n1ptr, *n2ptr, *pvptr; + char *n1end, *n2end; /* To the end of n1 and n2. */ + int indx, sum, prodlen; + + prodlen = n1len+n2len+1; + + *prod = bc_new_num (prodlen, 0); + + n1end = (char *) (n1->n_value + n1len - 1); + n2end = (char *) (n2->n_value + n2len - 1); + pvptr = (char *) ((*prod)->n_value + prodlen - 1); + sum = 0; + + /* Here is the loop... */ + for (indx = 0; indx < prodlen-1; indx++) + { + n1ptr = (char *) (n1end - MAX(0, indx-n2len+1)); + n2ptr = (char *) (n2end - MIN(indx, n2len-1)); + while ((n1ptr >= n1->n_value) && (n2ptr <= n2end)) + sum += *n1ptr-- * *n2ptr++; + *pvptr-- = sum % BASE; + sum = sum / BASE; + } + *pvptr = sum; +} + + +/* A special adder/subtractor for the recursive divide and conquer + multiply algorithm. Note: if sub is called, accum must + be larger that what is being subtracted. Also, accum and val + must have n_scale = 0. (e.g. they must look like integers. *) */ +static void +_bc_shift_addsub (bc_num accum, bc_num val, int shift, int sub) +{ + signed char *accp, *valp; + int count, carry; + + count = val->n_len; + if (val->n_value[0] == 0) + count--; + assert (accum->n_len+accum->n_scale >= shift+count); + + /* Set up pointers and others */ + accp = (signed char *)(accum->n_value + + accum->n_len + accum->n_scale - shift - 1); + valp = (signed char *)(val->n_value + val->n_len - 1); + carry = 0; + + if (sub) { + /* Subtraction, carry is really borrow. */ + while (count--) { + *accp -= *valp-- + carry; + if (*accp < 0) { + carry = 1; + *accp-- += BASE; + } else { + carry = 0; + accp--; + } + } + while (carry) { + *accp -= carry; + if (*accp < 0) + *accp-- += BASE; + else + carry = 0; + } + } else { + /* Addition */ + while (count--) { + *accp += *valp-- + carry; + if (*accp > (BASE-1)) { + carry = 1; + *accp-- -= BASE; + } else { + carry = 0; + accp--; + } + } + while (carry) { + *accp += carry; + if (*accp > (BASE-1)) + *accp-- -= BASE; + else + carry = 0; + } + } +} + +/* Recursive divide and conquer multiply algorithm. + Based on + Let u = u0 + u1*(b^n) + Let v = v0 + v1*(b^n) + Then uv = (B^2n+B^n)*u1*v1 + B^n*(u1-u0)*(v0-v1) + (B^n+1)*u0*v0 + + B is the base of storage, number of digits in u1,u0 close to equal. +*/ +static void +_bc_rec_mul (bc_num u, int ulen, bc_num v, int vlen, bc_num *prod, + int full_scale TSRMLS_DC) +{ + bc_num u0, u1, v0, v1; + int u0len, v0len; + bc_num m1, m2, m3, d1, d2; + int n, prodlen, m1zero; + int d1len, d2len; + + /* Base case? */ + if ((ulen+vlen) < mul_base_digits + || ulen < MUL_SMALL_DIGITS + || vlen < MUL_SMALL_DIGITS ) { + _bc_simp_mul (u, ulen, v, vlen, prod, full_scale); + return; + } + + /* Calculate n -- the u and v split point in digits. */ + n = (MAX(ulen, vlen)+1) / 2; + + /* Split u and v. */ + if (ulen < n) { + u1 = bc_copy_num (BCG(_zero_)); + u0 = new_sub_num (ulen,0, u->n_value); + } else { + u1 = new_sub_num (ulen-n, 0, u->n_value); + u0 = new_sub_num (n, 0, u->n_value+ulen-n); + } + if (vlen < n) { + v1 = bc_copy_num (BCG(_zero_)); + v0 = new_sub_num (vlen,0, v->n_value); + } else { + v1 = new_sub_num (vlen-n, 0, v->n_value); + v0 = new_sub_num (n, 0, v->n_value+vlen-n); + } + _bc_rm_leading_zeros (u1); + _bc_rm_leading_zeros (u0); + u0len = u0->n_len; + _bc_rm_leading_zeros (v1); + _bc_rm_leading_zeros (v0); + v0len = v0->n_len; + + m1zero = bc_is_zero(u1 TSRMLS_CC) || bc_is_zero(v1 TSRMLS_CC); + + /* Calculate sub results ... */ + + bc_init_num(&d1 TSRMLS_CC); + bc_init_num(&d2 TSRMLS_CC); + bc_sub (u1, u0, &d1, 0); + d1len = d1->n_len; + bc_sub (v0, v1, &d2, 0); + d2len = d2->n_len; + + + /* Do recursive multiplies and shifted adds. */ + if (m1zero) + m1 = bc_copy_num (BCG(_zero_)); + else + _bc_rec_mul (u1, u1->n_len, v1, v1->n_len, &m1, 0 TSRMLS_CC); + + if (bc_is_zero(d1 TSRMLS_CC) || bc_is_zero(d2 TSRMLS_CC)) + m2 = bc_copy_num (BCG(_zero_)); + else + _bc_rec_mul (d1, d1len, d2, d2len, &m2, 0 TSRMLS_CC); + + if (bc_is_zero(u0 TSRMLS_CC) || bc_is_zero(v0 TSRMLS_CC)) + m3 = bc_copy_num (BCG(_zero_)); + else + _bc_rec_mul (u0, u0->n_len, v0, v0->n_len, &m3, 0 TSRMLS_CC); + + /* Initialize product */ + prodlen = ulen+vlen+1; + *prod = bc_new_num(prodlen, 0); + + if (!m1zero) { + _bc_shift_addsub (*prod, m1, 2*n, 0); + _bc_shift_addsub (*prod, m1, n, 0); + } + _bc_shift_addsub (*prod, m3, n, 0); + _bc_shift_addsub (*prod, m3, 0, 0); + _bc_shift_addsub (*prod, m2, n, d1->n_sign != d2->n_sign); + + /* Now clean up! */ + bc_free_num (&u1); + bc_free_num (&u0); + bc_free_num (&v1); + bc_free_num (&m1); + bc_free_num (&v0); + bc_free_num (&m2); + bc_free_num (&m3); + bc_free_num (&d1); + bc_free_num (&d2); +} + +/* The multiply routine. N2 times N1 is put int PROD with the scale of + the result being MIN(N2 scale+N1 scale, MAX (SCALE, N2 scale, N1 scale)). + */ + +void +bc_multiply (bc_num n1, bc_num n2, bc_num *prod, int scale TSRMLS_DC) +{ + bc_num pval; + int len1, len2; + int full_scale, prod_scale; + + /* Initialize things. */ + len1 = n1->n_len + n1->n_scale; + len2 = n2->n_len + n2->n_scale; + full_scale = n1->n_scale + n2->n_scale; + prod_scale = MIN(full_scale,MAX(scale,MAX(n1->n_scale,n2->n_scale))); + + /* Do the multiply */ + _bc_rec_mul (n1, len1, n2, len2, &pval, full_scale TSRMLS_CC); + + /* Assign to prod and clean up the number. */ + pval->n_sign = ( n1->n_sign == n2->n_sign ? PLUS : MINUS ); + pval->n_value = pval->n_ptr; + pval->n_len = len2 + len1 + 1 - full_scale; + pval->n_scale = prod_scale; + _bc_rm_leading_zeros (pval); + if (bc_is_zero (pval TSRMLS_CC)) + pval->n_sign = PLUS; + bc_free_num (prod); + *prod = pval; +} |