1 |
matty |
32 |
/* crypto/bn/bn_div.c */ |
2 |
|
|
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
3 |
|
|
* All rights reserved. |
4 |
|
|
* |
5 |
|
|
* This package is an SSL implementation written |
6 |
|
|
* by Eric Young (eay@cryptsoft.com). |
7 |
|
|
* The implementation was written so as to conform with Netscapes SSL. |
8 |
|
|
* |
9 |
|
|
* This library is free for commercial and non-commercial use as long as |
10 |
|
|
* the following conditions are aheared to. The following conditions |
11 |
|
|
* apply to all code found in this distribution, be it the RC4, RSA, |
12 |
|
|
* lhash, DES, etc., code; not just the SSL code. The SSL documentation |
13 |
|
|
* included with this distribution is covered by the same copyright terms |
14 |
|
|
* except that the holder is Tim Hudson (tjh@cryptsoft.com). |
15 |
|
|
* |
16 |
|
|
* Copyright remains Eric Young's, and as such any Copyright notices in |
17 |
|
|
* the code are not to be removed. |
18 |
|
|
* If this package is used in a product, Eric Young should be given attribution |
19 |
|
|
* as the author of the parts of the library used. |
20 |
|
|
* This can be in the form of a textual message at program startup or |
21 |
|
|
* in documentation (online or textual) provided with the package. |
22 |
|
|
* |
23 |
|
|
* Redistribution and use in source and binary forms, with or without |
24 |
|
|
* modification, are permitted provided that the following conditions |
25 |
|
|
* are met: |
26 |
|
|
* 1. Redistributions of source code must retain the copyright |
27 |
|
|
* notice, this list of conditions and the following disclaimer. |
28 |
|
|
* 2. Redistributions in binary form must reproduce the above copyright |
29 |
|
|
* notice, this list of conditions and the following disclaimer in the |
30 |
|
|
* documentation and/or other materials provided with the distribution. |
31 |
|
|
* 3. All advertising materials mentioning features or use of this software |
32 |
|
|
* must display the following acknowledgement: |
33 |
|
|
* "This product includes cryptographic software written by |
34 |
|
|
* Eric Young (eay@cryptsoft.com)" |
35 |
|
|
* The word 'cryptographic' can be left out if the rouines from the library |
36 |
|
|
* being used are not cryptographic related :-). |
37 |
|
|
* 4. If you include any Windows specific code (or a derivative thereof) from |
38 |
|
|
* the apps directory (application code) you must include an acknowledgement: |
39 |
|
|
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
40 |
|
|
* |
41 |
|
|
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
42 |
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
43 |
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
44 |
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
45 |
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
46 |
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
47 |
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
48 |
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
49 |
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
50 |
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
51 |
|
|
* SUCH DAMAGE. |
52 |
|
|
* |
53 |
|
|
* The licence and distribution terms for any publically available version or |
54 |
|
|
* derivative of this code cannot be changed. i.e. this code cannot simply be |
55 |
|
|
* copied and put under another distribution licence |
56 |
|
|
* [including the GNU Public Licence.] |
57 |
|
|
*/ |
58 |
|
|
|
59 |
|
|
#include <stdio.h> |
60 |
|
|
#include "bn.h" |
61 |
|
|
#include "bn_lcl.h" |
62 |
|
|
|
63 |
|
|
/* The old slow way */ |
64 |
|
|
#if 0 |
65 |
|
|
int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, |
66 |
|
|
BN_CTX *ctx) |
67 |
|
|
{ |
68 |
|
|
int i,nm,nd; |
69 |
|
|
int ret = 0; |
70 |
|
|
BIGNUM *D; |
71 |
|
|
|
72 |
|
|
bn_check_top(m); |
73 |
|
|
bn_check_top(d); |
74 |
|
|
if (BN_is_zero(d)) |
75 |
|
|
{ |
76 |
|
|
BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO); |
77 |
|
|
return(0); |
78 |
|
|
} |
79 |
|
|
|
80 |
|
|
if (BN_ucmp(m,d) < 0) |
81 |
|
|
{ |
82 |
|
|
if (rem != NULL) |
83 |
|
|
{ if (BN_copy(rem,m) == NULL) return(0); } |
84 |
|
|
if (dv != NULL) BN_zero(dv); |
85 |
|
|
return(1); |
86 |
|
|
} |
87 |
|
|
|
88 |
|
|
BN_CTX_start(ctx); |
89 |
|
|
D = BN_CTX_get(ctx); |
90 |
|
|
if (dv == NULL) dv = BN_CTX_get(ctx); |
91 |
|
|
if (rem == NULL) rem = BN_CTX_get(ctx); |
92 |
|
|
if (D == NULL || dv == NULL || rem == NULL) |
93 |
|
|
goto end; |
94 |
|
|
|
95 |
|
|
nd=BN_num_bits(d); |
96 |
|
|
nm=BN_num_bits(m); |
97 |
|
|
if (BN_copy(D,d) == NULL) goto end; |
98 |
|
|
if (BN_copy(rem,m) == NULL) goto end; |
99 |
|
|
|
100 |
|
|
/* The next 2 are needed so we can do a dv->d[0]|=1 later |
101 |
|
|
* since BN_lshift1 will only work once there is a value :-) */ |
102 |
|
|
BN_zero(dv); |
103 |
|
|
bn_wexpand(dv,1); |
104 |
|
|
dv->top=1; |
105 |
|
|
|
106 |
|
|
if (!BN_lshift(D,D,nm-nd)) goto end; |
107 |
|
|
for (i=nm-nd; i>=0; i--) |
108 |
|
|
{ |
109 |
|
|
if (!BN_lshift1(dv,dv)) goto end; |
110 |
|
|
if (BN_ucmp(rem,D) >= 0) |
111 |
|
|
{ |
112 |
|
|
dv->d[0]|=1; |
113 |
|
|
if (!BN_usub(rem,rem,D)) goto end; |
114 |
|
|
} |
115 |
|
|
/* CAN IMPROVE (and have now :=) */ |
116 |
|
|
if (!BN_rshift1(D,D)) goto end; |
117 |
|
|
} |
118 |
|
|
rem->neg=BN_is_zero(rem)?0:m->neg; |
119 |
|
|
dv->neg=m->neg^d->neg; |
120 |
|
|
ret = 1; |
121 |
|
|
end: |
122 |
|
|
BN_CTX_end(ctx); |
123 |
|
|
return(ret); |
124 |
|
|
} |
125 |
|
|
|
126 |
|
|
#else |
127 |
|
|
|
128 |
|
|
#if !defined(NO_ASM) && !defined(NO_INLINE_ASM) && !defined(PEDANTIC) && !defined(BN_DIV3W) |
129 |
|
|
# if defined(__GNUC__) && __GNUC__>=2 |
130 |
matthewc |
195 |
# if defined(__i386) || defined (__i386__) |
131 |
matty |
32 |
/* |
132 |
|
|
* There were two reasons for implementing this template: |
133 |
|
|
* - GNU C generates a call to a function (__udivdi3 to be exact) |
134 |
|
|
* in reply to ((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0 (I fail to |
135 |
|
|
* understand why...); |
136 |
|
|
* - divl doesn't only calculate quotient, but also leaves |
137 |
|
|
* remainder in %edx which we can definitely use here:-) |
138 |
|
|
* |
139 |
|
|
* <appro@fy.chalmers.se> |
140 |
|
|
*/ |
141 |
|
|
# define bn_div_words(n0,n1,d0) \ |
142 |
|
|
({ asm volatile ( \ |
143 |
|
|
"divl %4" \ |
144 |
|
|
: "=a"(q), "=d"(rem) \ |
145 |
|
|
: "a"(n1), "d"(n0), "g"(d0) \ |
146 |
|
|
: "cc"); \ |
147 |
|
|
q; \ |
148 |
|
|
}) |
149 |
|
|
# define REMAINDER_IS_ALREADY_CALCULATED |
150 |
|
|
# endif /* __<cpu> */ |
151 |
|
|
# endif /* __GNUC__ */ |
152 |
|
|
#endif /* NO_ASM */ |
153 |
|
|
|
154 |
|
|
int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, |
155 |
|
|
BN_CTX *ctx) |
156 |
|
|
{ |
157 |
|
|
int norm_shift,i,j,loop; |
158 |
|
|
BIGNUM *tmp,wnum,*snum,*sdiv,*res; |
159 |
|
|
BN_ULONG *resp,*wnump; |
160 |
|
|
BN_ULONG d0,d1; |
161 |
|
|
int num_n,div_n; |
162 |
|
|
|
163 |
|
|
bn_check_top(num); |
164 |
|
|
bn_check_top(divisor); |
165 |
|
|
|
166 |
|
|
if (BN_is_zero(divisor)) |
167 |
|
|
{ |
168 |
|
|
BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO); |
169 |
|
|
return(0); |
170 |
|
|
} |
171 |
|
|
|
172 |
|
|
if (BN_ucmp(num,divisor) < 0) |
173 |
|
|
{ |
174 |
|
|
if (rm != NULL) |
175 |
|
|
{ if (BN_copy(rm,num) == NULL) return(0); } |
176 |
|
|
if (dv != NULL) BN_zero(dv); |
177 |
|
|
return(1); |
178 |
|
|
} |
179 |
|
|
|
180 |
|
|
BN_CTX_start(ctx); |
181 |
|
|
tmp=BN_CTX_get(ctx); |
182 |
|
|
snum=BN_CTX_get(ctx); |
183 |
|
|
sdiv=BN_CTX_get(ctx); |
184 |
|
|
if (dv == NULL) |
185 |
|
|
res=BN_CTX_get(ctx); |
186 |
|
|
else res=dv; |
187 |
|
|
if (sdiv==NULL || res == NULL) goto err; |
188 |
|
|
tmp->neg=0; |
189 |
|
|
|
190 |
|
|
/* First we normalise the numbers */ |
191 |
|
|
norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2); |
192 |
matthewc |
195 |
if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err; |
193 |
matty |
32 |
sdiv->neg=0; |
194 |
|
|
norm_shift+=BN_BITS2; |
195 |
matthewc |
195 |
if (!(BN_lshift(snum,num,norm_shift))) goto err; |
196 |
matty |
32 |
snum->neg=0; |
197 |
|
|
div_n=sdiv->top; |
198 |
|
|
num_n=snum->top; |
199 |
|
|
loop=num_n-div_n; |
200 |
|
|
|
201 |
|
|
/* Lets setup a 'window' into snum |
202 |
|
|
* This is the part that corresponds to the current |
203 |
|
|
* 'area' being divided */ |
204 |
|
|
BN_init(&wnum); |
205 |
|
|
wnum.d= &(snum->d[loop]); |
206 |
|
|
wnum.top= div_n; |
207 |
|
|
wnum.dmax= snum->dmax+1; /* a bit of a lie */ |
208 |
|
|
|
209 |
|
|
/* Get the top 2 words of sdiv */ |
210 |
|
|
/* i=sdiv->top; */ |
211 |
|
|
d0=sdiv->d[div_n-1]; |
212 |
|
|
d1=(div_n == 1)?0:sdiv->d[div_n-2]; |
213 |
|
|
|
214 |
|
|
/* pointer to the 'top' of snum */ |
215 |
|
|
wnump= &(snum->d[num_n-1]); |
216 |
|
|
|
217 |
|
|
/* Setup to 'res' */ |
218 |
|
|
res->neg= (num->neg^divisor->neg); |
219 |
|
|
if (!bn_wexpand(res,(loop+1))) goto err; |
220 |
|
|
res->top=loop; |
221 |
|
|
resp= &(res->d[loop-1]); |
222 |
|
|
|
223 |
|
|
/* space for temp */ |
224 |
|
|
if (!bn_wexpand(tmp,(div_n+1))) goto err; |
225 |
|
|
|
226 |
|
|
if (BN_ucmp(&wnum,sdiv) >= 0) |
227 |
|
|
{ |
228 |
|
|
if (!BN_usub(&wnum,&wnum,sdiv)) goto err; |
229 |
|
|
*resp=1; |
230 |
|
|
res->d[res->top-1]=1; |
231 |
|
|
} |
232 |
|
|
else |
233 |
|
|
res->top--; |
234 |
|
|
resp--; |
235 |
|
|
|
236 |
|
|
for (i=0; i<loop-1; i++) |
237 |
|
|
{ |
238 |
|
|
BN_ULONG q,l0; |
239 |
|
|
#if defined(BN_DIV3W) && !defined(NO_ASM) |
240 |
|
|
BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG); |
241 |
|
|
q=bn_div_3_words(wnump,d1,d0); |
242 |
|
|
#else |
243 |
|
|
BN_ULONG n0,n1,rem=0; |
244 |
|
|
|
245 |
|
|
n0=wnump[0]; |
246 |
|
|
n1=wnump[-1]; |
247 |
|
|
if (n0 == d0) |
248 |
|
|
q=BN_MASK2; |
249 |
|
|
else /* n0 < d0 */ |
250 |
|
|
{ |
251 |
|
|
#ifdef BN_LLONG |
252 |
|
|
BN_ULLONG t2; |
253 |
|
|
|
254 |
|
|
#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words) |
255 |
|
|
q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0); |
256 |
|
|
#else |
257 |
|
|
q=bn_div_words(n0,n1,d0); |
258 |
|
|
#endif |
259 |
|
|
|
260 |
|
|
#ifndef REMAINDER_IS_ALREADY_CALCULATED |
261 |
|
|
/* |
262 |
|
|
* rem doesn't have to be BN_ULLONG. The least we |
263 |
|
|
* know it's less that d0, isn't it? |
264 |
|
|
*/ |
265 |
|
|
rem=(n1-q*d0)&BN_MASK2; |
266 |
|
|
#endif |
267 |
|
|
t2=(BN_ULLONG)d1*q; |
268 |
|
|
|
269 |
|
|
for (;;) |
270 |
|
|
{ |
271 |
|
|
if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2])) |
272 |
|
|
break; |
273 |
|
|
q--; |
274 |
|
|
rem += d0; |
275 |
|
|
if (rem < d0) break; /* don't let rem overflow */ |
276 |
|
|
t2 -= d1; |
277 |
|
|
} |
278 |
|
|
#else /* !BN_LLONG */ |
279 |
|
|
BN_ULONG t2l,t2h,ql,qh; |
280 |
|
|
|
281 |
|
|
q=bn_div_words(n0,n1,d0); |
282 |
|
|
#ifndef REMAINDER_IS_ALREADY_CALCULATED |
283 |
|
|
rem=(n1-q*d0)&BN_MASK2; |
284 |
|
|
#endif |
285 |
|
|
|
286 |
|
|
#ifdef BN_UMULT_HIGH |
287 |
|
|
t2l = d1 * q; |
288 |
|
|
t2h = BN_UMULT_HIGH(d1,q); |
289 |
|
|
#else |
290 |
|
|
t2l=LBITS(d1); t2h=HBITS(d1); |
291 |
|
|
ql =LBITS(q); qh =HBITS(q); |
292 |
|
|
mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */ |
293 |
|
|
#endif |
294 |
|
|
|
295 |
|
|
for (;;) |
296 |
|
|
{ |
297 |
|
|
if ((t2h < rem) || |
298 |
|
|
((t2h == rem) && (t2l <= wnump[-2]))) |
299 |
|
|
break; |
300 |
|
|
q--; |
301 |
|
|
rem += d0; |
302 |
|
|
if (rem < d0) break; /* don't let rem overflow */ |
303 |
|
|
if (t2l < d1) t2h--; t2l -= d1; |
304 |
|
|
} |
305 |
|
|
#endif /* !BN_LLONG */ |
306 |
|
|
} |
307 |
|
|
#endif /* !BN_DIV3W */ |
308 |
|
|
|
309 |
|
|
l0=bn_mul_words(tmp->d,sdiv->d,div_n,q); |
310 |
|
|
wnum.d--; wnum.top++; |
311 |
|
|
tmp->d[div_n]=l0; |
312 |
|
|
for (j=div_n+1; j>0; j--) |
313 |
|
|
if (tmp->d[j-1]) break; |
314 |
|
|
tmp->top=j; |
315 |
|
|
|
316 |
|
|
j=wnum.top; |
317 |
matthewc |
195 |
if (!BN_sub(&wnum,&wnum,tmp)) goto err; |
318 |
matty |
32 |
|
319 |
|
|
snum->top=snum->top+wnum.top-j; |
320 |
|
|
|
321 |
|
|
if (wnum.neg) |
322 |
|
|
{ |
323 |
|
|
q--; |
324 |
|
|
j=wnum.top; |
325 |
matthewc |
195 |
if (!BN_add(&wnum,&wnum,sdiv)) goto err; |
326 |
matty |
32 |
snum->top+=wnum.top-j; |
327 |
|
|
} |
328 |
|
|
*(resp--)=q; |
329 |
|
|
wnump--; |
330 |
|
|
} |
331 |
|
|
if (rm != NULL) |
332 |
|
|
{ |
333 |
|
|
BN_rshift(rm,snum,norm_shift); |
334 |
|
|
rm->neg=num->neg; |
335 |
|
|
} |
336 |
|
|
BN_CTX_end(ctx); |
337 |
|
|
return(1); |
338 |
|
|
err: |
339 |
|
|
BN_CTX_end(ctx); |
340 |
|
|
return(0); |
341 |
|
|
} |
342 |
|
|
|
343 |
|
|
#endif |
344 |
|
|
|
345 |
|
|
/* rem != m */ |
346 |
|
|
int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) |
347 |
|
|
{ |
348 |
|
|
#if 0 /* The old slow way */ |
349 |
|
|
int i,nm,nd; |
350 |
|
|
BIGNUM *dv; |
351 |
|
|
|
352 |
|
|
if (BN_ucmp(m,d) < 0) |
353 |
|
|
return((BN_copy(rem,m) == NULL)?0:1); |
354 |
|
|
|
355 |
|
|
BN_CTX_start(ctx); |
356 |
|
|
dv=BN_CTX_get(ctx); |
357 |
|
|
|
358 |
|
|
if (!BN_copy(rem,m)) goto err; |
359 |
|
|
|
360 |
|
|
nm=BN_num_bits(rem); |
361 |
|
|
nd=BN_num_bits(d); |
362 |
|
|
if (!BN_lshift(dv,d,nm-nd)) goto err; |
363 |
|
|
for (i=nm-nd; i>=0; i--) |
364 |
|
|
{ |
365 |
|
|
if (BN_cmp(rem,dv) >= 0) |
366 |
|
|
{ |
367 |
|
|
if (!BN_sub(rem,rem,dv)) goto err; |
368 |
|
|
} |
369 |
|
|
if (!BN_rshift1(dv,dv)) goto err; |
370 |
|
|
} |
371 |
|
|
BN_CTX_end(ctx); |
372 |
|
|
return(1); |
373 |
|
|
err: |
374 |
|
|
BN_CTX_end(ctx); |
375 |
|
|
return(0); |
376 |
|
|
#else |
377 |
|
|
return(BN_div(NULL,rem,m,d,ctx)); |
378 |
|
|
#endif |
379 |
|
|
} |
380 |
|
|
|