1 /* mpn_get_str -- Convert a MSIZE long limb vector pointed to by MPTR
2 to a printable string in STR in base BASE.
4 Copyright (C) 1991, 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
6 This file is part of the GNU MP Library.
8 The GNU MP Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Library General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or (at your
11 option) any later version.
13 The GNU MP Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
16 License for more details.
18 You should have received a copy of the GNU Library General Public License
19 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
20 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21 MA 02111-1307, USA. */
27 /* Convert the limb vector pointed to by MPTR and MSIZE long to a
28 char array, using base BASE for the result array. Store the
29 result in the character array STR. STR must point to an array with
30 space for the largest possible number represented by a MSIZE long
31 limb vector + 1 extra character.
33 The result is NOT in Ascii, to convert it to printable format, add
34 '0' or 'A' depending on the base and range.
36 Return the number of digits in the result string.
37 This may include some leading zeros.
39 The limb vector pointed to by MPTR is clobbered. */
42 mpn_get_str (str, base, mptr, msize)
49 #if UDIV_NEEDS_NORMALIZATION || UDIV_TIME > 2 * UMUL_TIME
50 int normalization_steps;
52 #if UDIV_TIME > 2 * UMUL_TIME
53 mp_limb_t big_base_inverted;
55 unsigned int dig_per_u;
57 register unsigned char *s;
59 big_base = __mp_bases[base].big_base;
63 /* Special case zero, as the code below doesn't handle it. */
70 if ((base & (base - 1)) == 0)
72 /* The base is a power of 2. Make conversion from most
75 register int bits_per_digit = big_base;
81 count_leading_zeros (x, n1);
83 /* BIT_POS should be R when input ends in least sign. nibble,
84 R + bits_per_digit * n when input ends in n:th least significant
90 bits = BITS_PER_MP_LIMB * msize - x;
91 x = bits % bits_per_digit;
93 bits += bits_per_digit - x;
94 bit_pos = bits - (msize - 1) * BITS_PER_MP_LIMB;
97 /* Fast loop for bit output. */
101 bit_pos -= bits_per_digit;
104 *s++ = (n1 >> bit_pos) & ((1 << bits_per_digit) - 1);
105 bit_pos -= bits_per_digit;
110 n0 = (n1 << -bit_pos) & ((1 << bits_per_digit) - 1);
112 bit_pos += BITS_PER_MP_LIMB;
113 *s++ = n0 | (n1 >> bit_pos);
122 /* General case. The base is not a power of 2. Make conversion
123 from least significant end. */
125 /* If udiv_qrnnd only handles divisors with the most significant bit
126 set, prepare BIG_BASE for being a divisor by shifting it to the
127 left exactly enough to set the most significant bit. */
128 #if UDIV_NEEDS_NORMALIZATION || UDIV_TIME > 2 * UMUL_TIME
129 count_leading_zeros (normalization_steps, big_base);
130 big_base <<= normalization_steps;
131 #if UDIV_TIME > 2 * UMUL_TIME
132 /* Get the fixed-point approximation to 1/(BIG_BASE << NORMALIZATION_STEPS). */
133 big_base_inverted = __mp_bases[base].big_base_inverted;
137 dig_per_u = __mp_bases[base].chars_per_limb;
138 out_len = ((size_t) msize * BITS_PER_MP_LIMB
139 * __mp_bases[base].chars_per_bit_exactly) + 1;
147 #if UDIV_NEEDS_NORMALIZATION || UDIV_TIME > 2 * UMUL_TIME
148 /* If we shifted BIG_BASE above, shift the dividend too, to get
149 the right quotient. We need to do this every loop,
150 since the intermediate quotients are OK, but the quotient from
151 one turn in the loop is going to be the dividend in the
152 next turn, and the dividend needs to be up-shifted. */
153 if (normalization_steps != 0)
155 n0 = mpn_lshift (mptr, mptr, msize, normalization_steps);
157 /* If the shifting gave a carry out limb, store it and
158 increase the length. */
167 /* Divide the number at TP with BIG_BASE to get a quotient and a
168 remainder. The remainder is our new digit in base BIG_BASE. */
183 #if UDIV_TIME > 2 * UMUL_TIME
184 udiv_qrnnd_preinv (mptr[i], n1, n1, n0, big_base, big_base_inverted);
186 udiv_qrnnd (mptr[i], n1, n1, n0, big_base);
190 #if UDIV_NEEDS_NORMALIZATION || UDIV_TIME > 2 * UMUL_TIME
191 /* If we shifted above (at previous UDIV_NEEDS_NORMALIZATION tests)
192 the remainder will be up-shifted here. Compensate. */
193 n1 >>= normalization_steps;
196 /* Convert N1 from BIG_BASE to a string of digits in BASE
197 using single precision operations. */
198 for (i = dig_per_u - 1; i >= 0; i--)
202 if (n1 == 0 && msize == 0)