S390: Optimize memrchr.
[glibc.git] / stdio-common / _itowa.c
blobdedf4b7a9d156fd6a9e2a5faed32047274e58d95
1 /* Internal function for converting integers to ASCII.
2 Copyright (C) 1994-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Torbjorn Granlund <tege@matematik.su.se>
5 and Ulrich Drepper <drepper@gnu.org>.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <http://www.gnu.org/licenses/>. */
21 #include <gmp-mparam.h>
22 #include <gmp.h>
23 #include <limits.h>
24 #include <stdlib/gmp-impl.h>
25 #include <stdlib/longlong.h>
27 #include <_itowa.h>
30 /* Canonize environment. For some architectures not all values might
31 be defined in the GMP header files. */
32 #ifndef UMUL_TIME
33 # define UMUL_TIME 1
34 #endif
35 #ifndef UDIV_TIME
36 # define UDIV_TIME 3
37 #endif
39 /* Control memory layout. */
40 #ifdef PACK
41 # undef PACK
42 # define PACK __attribute__ ((packed))
43 #else
44 # define PACK
45 #endif
48 /* Declare local types. */
49 struct base_table_t
51 #if (UDIV_TIME > 2 * UMUL_TIME)
52 mp_limb_t base_multiplier;
53 #endif
54 char flag;
55 char post_shift;
56 #if BITS_PER_MP_LIMB == 32
57 struct
59 char normalization_steps;
60 char ndigits;
61 mp_limb_t base PACK;
62 #if UDIV_TIME > 2 * UMUL_TIME
63 mp_limb_t base_ninv PACK;
64 #endif
65 } big;
66 #endif
69 /* To reduce the memory needed we include some fields of the tables
70 only conditionally. */
71 #if UDIV_TIME > 2 * UMUL_TIME
72 # define SEL1(X) X,
73 # define SEL2(X) ,X
74 #else
75 # define SEL1(X)
76 # define SEL2(X)
77 #endif
79 /* Factor table for the different bases. */
80 extern const struct base_table_t _itoa_base_table[] attribute_hidden;
82 /* Lower-case digits. */
83 extern const wchar_t _itowa_lower_digits[] attribute_hidden;
84 /* Upper-case digits. */
85 extern const wchar_t _itowa_upper_digits[] attribute_hidden;
88 #if _ITOA_NEEDED
89 wchar_t *
90 _itowa (value, buflim, base, upper_case)
91 unsigned long long int value;
92 wchar_t *buflim;
93 unsigned int base;
94 int upper_case;
96 const wchar_t *digits = (upper_case
97 ? _itowa_upper_digits : _itowa_lower_digits);
98 wchar_t *bp = buflim;
99 const struct base_table_t *brec = &_itoa_base_table[base - 2];
101 switch (base)
103 # define RUN_2N(BITS) \
104 do \
106 /* `unsigned long long int' always has 64 bits. */ \
107 mp_limb_t work_hi = value >> (64 - BITS_PER_MP_LIMB); \
109 if (BITS_PER_MP_LIMB == 32) \
111 if (work_hi != 0) \
113 mp_limb_t work_lo; \
114 int cnt; \
116 work_lo = value & 0xfffffffful; \
117 for (cnt = BITS_PER_MP_LIMB / BITS; cnt > 0; --cnt) \
119 *--bp = digits[work_lo & ((1ul << BITS) - 1)]; \
120 work_lo >>= BITS; \
122 if (BITS_PER_MP_LIMB % BITS != 0) \
124 work_lo \
125 |= ((work_hi \
126 & ((1 << (BITS - BITS_PER_MP_LIMB%BITS)) \
127 - 1)) \
128 << BITS_PER_MP_LIMB % BITS); \
129 work_hi >>= BITS - BITS_PER_MP_LIMB % BITS; \
130 if (work_hi == 0) \
131 work_hi = work_lo; \
132 else \
133 *--bp = digits[work_lo]; \
136 else \
137 work_hi = value & 0xfffffffful; \
139 do \
141 *--bp = digits[work_hi & ((1 << BITS) - 1)]; \
142 work_hi >>= BITS; \
144 while (work_hi != 0); \
146 while (0)
147 case 8:
148 RUN_2N (3);
149 break;
151 case 16:
152 RUN_2N (4);
153 break;
155 default:
157 # if BITS_PER_MP_LIMB == 64
158 mp_limb_t base_multiplier = brec->base_multiplier;
159 if (brec->flag)
160 while (value != 0)
162 mp_limb_t quo, rem, x;
163 mp_limb_t dummy __attribute__ ((unused));
165 umul_ppmm (x, dummy, value, base_multiplier);
166 quo = (x + ((value - x) >> 1)) >> (brec->post_shift - 1);
167 rem = value - quo * base;
168 *--bp = digits[rem];
169 value = quo;
171 else
172 while (value != 0)
174 mp_limb_t quo, rem, x;
175 mp_limb_t dummy __attribute__ ((unused));
177 umul_ppmm (x, dummy, value, base_multiplier);
178 quo = x >> brec->post_shift;
179 rem = value - quo * base;
180 *--bp = digits[rem];
181 value = quo;
183 # endif
184 # if BITS_PER_MP_LIMB == 32
185 mp_limb_t t[3];
186 int n;
188 /* First convert x0 to 1-3 words in base s->big.base.
189 Optimize for frequent cases of 32 bit numbers. */
190 if ((mp_limb_t) (value >> 32) >= 1)
192 # if UDIV_TIME > 2 * UMUL_TIME || UDIV_NEEDS_NORMALIZATION
193 int big_normalization_steps = brec->big.normalization_steps;
194 mp_limb_t big_base_norm
195 = brec->big.base << big_normalization_steps;
196 # endif
197 if ((mp_limb_t) (value >> 32) >= brec->big.base)
199 mp_limb_t x1hi, x1lo, r;
200 /* If you want to optimize this, take advantage of
201 that the quotient in the first udiv_qrnnd will
202 always be very small. It might be faster just to
203 subtract in a tight loop. */
205 # if UDIV_TIME > 2 * UMUL_TIME
206 mp_limb_t x, xh, xl;
208 if (big_normalization_steps == 0)
209 xh = 0;
210 else
211 xh = (mp_limb_t) (value >> (64 - big_normalization_steps));
212 xl = (mp_limb_t) (value >> (32 - big_normalization_steps));
213 udiv_qrnnd_preinv (x1hi, r, xh, xl, big_base_norm,
214 brec->big.base_ninv);
216 xl = ((mp_limb_t) value) << big_normalization_steps;
217 udiv_qrnnd_preinv (x1lo, x, r, xl, big_base_norm,
218 brec->big.base_ninv);
219 t[2] = x >> big_normalization_steps;
221 if (big_normalization_steps == 0)
222 xh = x1hi;
223 else
224 xh = ((x1hi << big_normalization_steps)
225 | (x1lo >> (32 - big_normalization_steps)));
226 xl = x1lo << big_normalization_steps;
227 udiv_qrnnd_preinv (t[0], x, xh, xl, big_base_norm,
228 brec->big.base_ninv);
229 t[1] = x >> big_normalization_steps;
230 # elif UDIV_NEEDS_NORMALIZATION
231 mp_limb_t x, xh, xl;
233 if (big_normalization_steps == 0)
234 xh = 0;
235 else
236 xh = (mp_limb_t) (value >> 64 - big_normalization_steps);
237 xl = (mp_limb_t) (value >> 32 - big_normalization_steps);
238 udiv_qrnnd (x1hi, r, xh, xl, big_base_norm);
240 xl = ((mp_limb_t) value) << big_normalization_steps;
241 udiv_qrnnd (x1lo, x, r, xl, big_base_norm);
242 t[2] = x >> big_normalization_steps;
244 if (big_normalization_steps == 0)
245 xh = x1hi;
246 else
247 xh = ((x1hi << big_normalization_steps)
248 | (x1lo >> 32 - big_normalization_steps));
249 xl = x1lo << big_normalization_steps;
250 udiv_qrnnd (t[0], x, xh, xl, big_base_norm);
251 t[1] = x >> big_normalization_steps;
252 # else
253 udiv_qrnnd (x1hi, r, 0, (mp_limb_t) (value >> 32),
254 brec->big.base);
255 udiv_qrnnd (x1lo, t[2], r, (mp_limb_t) value, brec->big.base);
256 udiv_qrnnd (t[0], t[1], x1hi, x1lo, brec->big.base);
257 # endif
258 n = 3;
260 else
262 # if UDIV_TIME > 2 * UMUL_TIME
263 mp_limb_t x;
265 value <<= brec->big.normalization_steps;
266 udiv_qrnnd_preinv (t[0], x, (mp_limb_t) (value >> 32),
267 (mp_limb_t) value, big_base_norm,
268 brec->big.base_ninv);
269 t[1] = x >> brec->big.normalization_steps;
270 # elif UDIV_NEEDS_NORMALIZATION
271 mp_limb_t x;
273 value <<= big_normalization_steps;
274 udiv_qrnnd (t[0], x, (mp_limb_t) (value >> 32),
275 (mp_limb_t) value, big_base_norm);
276 t[1] = x >> big_normalization_steps;
277 # else
278 udiv_qrnnd (t[0], t[1], (mp_limb_t) (value >> 32),
279 (mp_limb_t) value, brec->big.base);
280 # endif
281 n = 2;
284 else
286 t[0] = value;
287 n = 1;
290 /* Convert the 1-3 words in t[], word by word, to ASCII. */
293 mp_limb_t ti = t[--n];
294 int ndig_for_this_limb = 0;
296 # if UDIV_TIME > 2 * UMUL_TIME
297 mp_limb_t base_multiplier = brec->base_multiplier;
298 if (brec->flag)
299 while (ti != 0)
301 mp_limb_t quo, rem, x;
302 mp_limb_t dummy __attribute__ ((unused));
304 umul_ppmm (x, dummy, ti, base_multiplier);
305 quo = (x + ((ti - x) >> 1)) >> (brec->post_shift - 1);
306 rem = ti - quo * base;
307 *--bp = digits[rem];
308 ti = quo;
309 ++ndig_for_this_limb;
311 else
312 while (ti != 0)
314 mp_limb_t quo, rem, x;
315 mp_limb_t dummy __attribute__ ((unused));
317 umul_ppmm (x, dummy, ti, base_multiplier);
318 quo = x >> brec->post_shift;
319 rem = ti - quo * base;
320 *--bp = digits[rem];
321 ti = quo;
322 ++ndig_for_this_limb;
324 # else
325 while (ti != 0)
327 mp_limb_t quo, rem;
329 quo = ti / base;
330 rem = ti % base;
331 *--bp = digits[rem];
332 ti = quo;
333 ++ndig_for_this_limb;
335 # endif
336 /* If this wasn't the most significant word, pad with zeros. */
337 if (n != 0)
338 while (ndig_for_this_limb < brec->big.ndigits)
340 *--bp = '0';
341 ++ndig_for_this_limb;
344 while (n != 0);
345 # endif
347 break;
350 return bp;
352 #endif