5e62d405232a8bf12499e00c652f24bdde9e3657
[openssl.git] / crypto / md32_common.h
1 /* crypto/md32_common.h */
2 /* ====================================================================
3  * Copyright (c) 1999 The OpenSSL Project.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer. 
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in
14  *    the documentation and/or other materials provided with the
15  *    distribution.
16  *
17  * 3. All advertising materials mentioning features or use of this
18  *    software must display the following acknowledgment:
19  *    "This product includes software developed by the OpenSSL Project
20  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
21  *
22  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23  *    endorse or promote products derived from this software without
24  *    prior written permission. For written permission, please contact
25  *    licensing@OpenSSL.org.
26  *
27  * 5. Products derived from this software may not be called "OpenSSL"
28  *    nor may "OpenSSL" appear in their names without prior written
29  *    permission of the OpenSSL Project.
30  *
31  * 6. Redistributions of any form whatsoever must retain the following
32  *    acknowledgment:
33  *    "This product includes software developed by the OpenSSL Project
34  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
35  *
36  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
40  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47  * OF THE POSSIBILITY OF SUCH DAMAGE.
48  * ====================================================================
49  *
50  * This product includes cryptographic software written by Eric Young
51  * (eay@cryptsoft.com).  This product includes software written by Tim
52  * Hudson (tjh@cryptsoft.com).
53  *
54  */
55
56 /*
57  * This is a generic 32 bit "collector" for message digest algorithms.
58  * Whenever needed it collects input character stream into chunks of
59  * 32 bit values and invokes a block function that performs actual hash
60  * calculations.
61  *
62  * Porting guide.
63  *
64  * Obligatory macros:
65  *
66  * DATA_ORDER_IS_BIG_ENDIAN or DATA_ORDER_IS_LITTLE_ENDIAN
67  *      this macro defines byte order of input stream.
68  * HASH_CBLOCK
69  *      size of a unit chunk HASH_BLOCK operates on.
70  * HASH_LONG
71  *      has to be at lest 32 bit wide, if it's wider, then
72  *      HASH_LONG_LOG2 *has to* be defined along
73  * HASH_CTX
74  *      context structure that at least contains following
75  *      members:
76  *              typedef struct {
77  *                      ...
78  *                      HASH_LONG       Nl,Nh;
79  *                      HASH_LONG       data[HASH_LBLOCK];
80  *                      int             num;
81  *                      ...
82  *                      } HASH_CTX;
83  * HASH_UPDATE
84  *      name of "Update" function, implemented here.
85  * HASH_TRANSFORM
86  *      name of "Transform" function, implemented here.
87  * HASH_FINAL
88  *      name of "Final" function, implemented here.
89  * HASH_BLOCK_HOST_ORDER
90  *      name of "block" function treating *aligned* input message
91  *      in host byte order, implemented externally.
92  * HASH_BLOCK_DATA_ORDER
93  *      name of "block" function treating *unaligned* input message
94  *      in original (data) byte order, implemented externally (it
95  *      actually is optional if data and host are of the same
96  *      "endianess").
97  * HASH_MAKE_STRING
98  *      macro convering context variables to an ASCII hash string.
99  *
100  * Optional macros:
101  *
102  * B_ENDIAN or L_ENDIAN
103  *      defines host byte-order.
104  * HASH_LONG_LOG2
105  *      defaults to 2 if not states otherwise.
106  * HASH_LBLOCK
107  *      assumed to be HASH_CBLOCK/4 if not stated otherwise.
108  * HASH_BLOCK_DATA_ORDER_ALIGNED
109  *      alternative "block" function capable of treating
110  *      aligned input message in original (data) order,
111  *      implemented externally.
112  *
113  * MD5 example:
114  *
115  *      #define DATA_ORDER_IS_LITTLE_ENDIAN
116  *
117  *      #define HASH_LONG               MD5_LONG
118  *      #define HASH_LONG_LOG2          MD5_LONG_LOG2
119  *      #define HASH_CTX                MD5_CTX
120  *      #define HASH_CBLOCK             MD5_CBLOCK
121  *      #define HASH_LBLOCK             MD5_LBLOCK
122  *      #define HASH_UPDATE             MD5_Update
123  *      #define HASH_TRANSFORM          MD5_Transform
124  *      #define HASH_FINAL              MD5_Final
125  *      #define HASH_BLOCK_HOST_ORDER   md5_block_host_order
126  *      #define HASH_BLOCK_DATA_ORDER   md5_block_data_order
127  *
128  *                                      <appro@fy.chalmers.se>
129  */
130
131 #if !defined(DATA_ORDER_IS_BIG_ENDIAN) && !defined(DATA_ORDER_IS_LITTLE_ENDIAN)
132 #error "DATA_ORDER must be defined!"
133 #endif
134
135 #ifndef HASH_CBLOCK
136 #error "HASH_CBLOCK must be defined!"
137 #endif
138 #ifndef HASH_LONG
139 #error "HASH_LONG must be defined!"
140 #endif
141 #ifndef HASH_CTX
142 #error "HASH_CTX must be defined!"
143 #endif
144
145 #ifndef HASH_UPDATE
146 #error "HASH_UPDATE must be defined!"
147 #endif
148 #ifndef HASH_TRANSFORM
149 #error "HASH_TRANSFORM must be defined!"
150 #endif
151 #ifndef HASH_FINAL
152 #error "HASH_FINAL must be defined!"
153 #endif
154
155 #ifndef HASH_BLOCK_HOST_ORDER
156 #error "HASH_BLOCK_HOST_ORDER must be defined!"
157 #endif
158
159 #if 0
160 /*
161  * Moved below as it's required only if HASH_BLOCK_DATA_ORDER_ALIGNED
162  * isn't defined.
163  */
164 #ifndef HASH_BLOCK_DATA_ORDER
165 #error "HASH_BLOCK_DATA_ORDER must be defined!"
166 #endif
167 #endif
168
169 #ifndef HASH_LBLOCK
170 #define HASH_LBLOCK     (HASH_CBLOCK/4)
171 #endif
172
173 #ifndef HASH_LONG_LOG2
174 #define HASH_LONG_LOG2  2
175 #endif
176
177 /*
178  * Engage compiler specific rotate intrinsic function if available.
179  */
180 #undef ROTATE
181 #ifndef PEDANTIC
182 # if defined(_MSC_VER)
183 #  define ROTATE(a,n)   _lrotl(a,n)
184 # elif defined(__MWERKS__)
185 #  define ROTATE(a,n)   __rol(a,n)
186 # elif defined(__GNUC__) && __GNUC__>=2 && !defined(NO_ASM)
187   /*
188    * Some GNU C inline assembler templates. Note that these are
189    * rotates by *constant* number of bits! But that's exactly
190    * what we need here...
191    *
192    *                                    <appro@fy.chalmers.se>
193    */
194 #  if defined(__i386)
195 #   define ROTATE(a,n)  ({ register unsigned int ret;   \
196                                 asm volatile (          \
197                                 "roll %1,%0"            \
198                                 : "=r"(ret)             \
199                                 : "I"(n), "0"(a)        \
200                                 : "cc");                \
201                            ret;                         \
202                         })
203 #  elif defined(__powerpc)
204 #   define ROTATE(a,n)  ({ register unsigned int ret;   \
205                                 asm volatile (          \
206                                 "rlwinm %0,%1,%2,0,31"  \
207                                 : "=r"(ret)             \
208                                 : "r"(a), "I"(n));      \
209                            ret;                         \
210                         })
211 #  endif
212 # endif
213
214 /*
215  * Engage compiler specific "fetch in reverse byte order"
216  * intrinsic function if available.
217  */
218 # if defined(__GNUC__) && __GNUC__>=2 && !defined(NO_ASM)
219   /* some GNU C inline assembler templates by <appro@fy.chalmers.se> */
220 #  if defined(__i386) && !defined(I386_ONLY)
221 #   define BE_FETCH32(a)        ({ register unsigned int l=(a);\
222                                 asm volatile (          \
223                                 "bswapl %0"             \
224                                 : "=r"(l) : "0"(l));    \
225                           l;                            \
226                         })
227 #  elif defined(__powerpc)
228 #   define LE_FETCH32(a)        ({ register unsigned int l;     \
229                                 asm volatile (          \
230                                 "lwbrx %0,0,%1"         \
231                                 : "=r"(l)               \
232                                 : "r"(a));              \
233                            l;                           \
234                         })
235
236 #  elif defined(__sparc) && defined(ULTRASPARC)
237 #  define LE_FETCH32(a) ({ register unsigned int l;             \
238                                 asm volatile (                  \
239                                 "lda [%1]#ASI_PRIMARY_LITTLE,%0"\
240                                 : "=r"(l)                       \
241                                 : "r"(a));                      \
242                            l;                                   \
243                         })
244 #  endif
245 # endif
246 #endif /* PEDANTIC */
247
248 #if HASH_LONG_LOG2==2   /* Engage only if sizeof(HASH_LONG)== 4 */
249 /* A nice byte order reversal from Wei Dai <weidai@eskimo.com> */
250 #ifdef ROTATE
251 /* 5 instructions with rotate instruction, else 9 */
252 #define REVERSE_FETCH32(a,l)    (                                       \
253                 l=*(const HASH_LONG *)(a),                              \
254                 ((ROTATE(l,8)&0x00FF00FF)|(ROTATE((l&0x00FF00FF),24)))  \
255                                 )
256 #else
257 /* 6 instructions with rotate instruction, else 8 */
258 #define REVERSE_FETCH32(a,l)    (                               \
259                 l=*(const HASH_LONG *)(a),                      \
260                 l=(((l>>8)&0x00FF00FF)|((l&0x00FF00FF)<<8)),    \
261                 ROTATE(l,16)                                    \
262                                 )
263 /*
264  * Originally the middle line started with l=(((l&0xFF00FF00)>>8)|...
265  * It's rewritten as above for two reasons:
266  *      - RISCs aren't good at long constants and have to explicitely
267  *        compose 'em with several (well, usually 2) instructions in a
268  *        register before performing the actual operation and (as you
269  *        already realized:-) having same constant should inspire the
270  *        compiler to permanently allocate the only register for it;
271  *      - most modern CPUs have two ALUs, but usually only one has
272  *        circuitry for shifts:-( this minor tweak inspires compiler
273  *        to schedule shift instructions in a better way...
274  *
275  *                              <appro@fy.chalmers.se>
276  */
277 #endif
278 #endif
279
280 #ifndef ROTATE
281 #define ROTATE(a,n)     (((a)<<(n))|(((a)&0xffffffff)>>(32-(n))))
282 #endif
283
284 /*
285  * Make some obvious choices. E.g., HASH_BLOCK_DATA_ORDER_ALIGNED
286  * and HASH_BLOCK_HOST_ORDER ought to be the same if input data
287  * and host are of the same "endianess". It's possible to mask
288  * this with blank #define HASH_BLOCK_DATA_ORDER though...
289  *
290  *                              <appro@fy.chalmers.se>
291  */
292 #if defined(B_ENDIAN)
293 #  if defined(DATA_ORDER_IS_BIG_ENDIAN)
294 #    if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED) && HASH_LONG_LOG2==2
295 #      define HASH_BLOCK_DATA_ORDER_ALIGNED     HASH_BLOCK_HOST_ORDER
296 #    endif
297 #  elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)
298 #    ifndef HOST_FETCH32
299 #      ifdef LE_FETCH32
300 #        define HOST_FETCH32(p,l)       LE_FETCH32(p)
301 #      elif defined(REVERSE_FETCH32)
302 #        define HOST_FETCH32(p,l)       REVERSE_FETCH32(p,l)
303 #      endif
304 #    endif
305 #  endif
306 #elif defined(L_ENDIAN)
307 #  if defined(DATA_ORDER_IS_LITTLE_ENDIAN)
308 #    if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED) && HASH_LONG_LOG2==2
309 #      define HASH_BLOCK_DATA_ORDER_ALIGNED     HASH_BLOCK_HOST_ORDER
310 #    endif
311 #  elif defined(DATA_ORDER_IS_BIG_ENDIAN)
312 #    ifndef HOST_FETCH32
313 #      ifdef BE_FETCH32
314 #        define HOST_FETCH32(p,l)       BE_FETCH32(p)
315 #      elif defined(REVERSE_FETCH32)
316 #        define HOST_FETCH32(p,l)       REVERSE_FETCH32(p,l)
317 #      endif
318 #    endif
319 #  endif
320 #endif
321
322 #if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
323 #ifndef HASH_BLOCK_DATA_ORDER
324 #error "HASH_BLOCK_DATA_ORDER must be defined!"
325 #endif
326 #endif
327
328 #if defined(DATA_ORDER_IS_BIG_ENDIAN)
329
330 #define HOST_c2l(c,l)   (l =(((unsigned long)(*((c)++)))<<24),          \
331                          l|=(((unsigned long)(*((c)++)))<<16),          \
332                          l|=(((unsigned long)(*((c)++)))<< 8),          \
333                          l|=(((unsigned long)(*((c)++)))    ),          \
334                          l)
335 #define HOST_p_c2l(c,l,n)       {                                       \
336                         switch (n) {                                    \
337                         case 0: l =((unsigned long)(*((c)++)))<<24;     \
338                         case 1: l|=((unsigned long)(*((c)++)))<<16;     \
339                         case 2: l|=((unsigned long)(*((c)++)))<< 8;     \
340                         case 3: l|=((unsigned long)(*((c)++)));         \
341                                 } }
342 #define HOST_p_c2l_p(c,l,sc,len) {                                      \
343                         switch (sc) {                                   \
344                         case 0: l =((unsigned long)(*((c)++)))<<24;     \
345                                 if (--len == 0) break;                  \
346                         case 1: l|=((unsigned long)(*((c)++)))<<16;     \
347                                 if (--len == 0) break;                  \
348                         case 2: l|=((unsigned long)(*((c)++)))<< 8;     \
349                                 } }
350 /* NOTE the pointer is not incremented at the end of this */
351 #define HOST_c2l_p(c,l,n)       {                                       \
352                         l=0; (c)+=n;                                    \
353                         switch (n) {                                    \
354                         case 3: l =((unsigned long)(*(--(c))))<< 8;     \
355                         case 2: l|=((unsigned long)(*(--(c))))<<16;     \
356                         case 1: l|=((unsigned long)(*(--(c))))<<24;     \
357                                 } }
358 #define HOST_l2c(l,c)   (*((c)++)=(unsigned char)(((l)>>24)&0xff),      \
359                          *((c)++)=(unsigned char)(((l)>>16)&0xff),      \
360                          *((c)++)=(unsigned char)(((l)>> 8)&0xff),      \
361                          *((c)++)=(unsigned char)(((l)    )&0xff),      \
362                          l)
363
364 #elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)
365
366 #define HOST_c2l(c,l)   (l =(((unsigned long)(*((c)++)))    ),          \
367                          l|=(((unsigned long)(*((c)++)))<< 8),          \
368                          l|=(((unsigned long)(*((c)++)))<<16),          \
369                          l|=(((unsigned long)(*((c)++)))<<24),          \
370                          l)
371 #define HOST_p_c2l(c,l,n)       {                                       \
372                         switch (n) {                                    \
373                         case 0: l =((unsigned long)(*((c)++)));         \
374                         case 1: l|=((unsigned long)(*((c)++)))<< 8;     \
375                         case 2: l|=((unsigned long)(*((c)++)))<<16;     \
376                         case 3: l|=((unsigned long)(*((c)++)))<<24;     \
377                                 } }
378 #define HOST_p_c2l_p(c,l,sc,len) {                                      \
379                         switch (sc) {                                   \
380                         case 0: l =((unsigned long)(*((c)++)));         \
381                                 if (--len == 0) break;                  \
382                         case 1: l|=((unsigned long)(*((c)++)))<< 8;     \
383                                 if (--len == 0) break;                  \
384                         case 2: l|=((unsigned long)(*((c)++)))<<16;     \
385                                 } }
386 /* NOTE the pointer is not incremented at the end of this */
387 #define HOST_c2l_p(c,l,n)       {                                       \
388                         l=0; (c)+=n;                                    \
389                         switch (n) {                                    \
390                         case 3: l =((unsigned long)(*(--(c))))<<16;     \
391                         case 2: l|=((unsigned long)(*(--(c))))<< 8;     \
392                         case 1: l|=((unsigned long)(*(--(c))));         \
393                                 } }
394 #define HOST_l2c(l,c)   (*((c)++)=(unsigned char)(((l)    )&0xff),      \
395                          *((c)++)=(unsigned char)(((l)>> 8)&0xff),      \
396                          *((c)++)=(unsigned char)(((l)>>16)&0xff),      \
397                          *((c)++)=(unsigned char)(((l)>>24)&0xff),      \
398                          l)
399
400 #endif
401
402 /*
403  * Time for some action:-)
404  */
405
406 void HASH_UPDATE (HASH_CTX *c, const unsigned char *data, unsigned long len)
407         {
408         register HASH_LONG * p;
409         register unsigned long l;
410         int sw,sc,ew,ec;
411
412         if (len==0) return;
413
414         l=(c->Nl+(len<<3))&0xffffffffL;
415         /* 95-05-24 eay Fixed a bug with the overflow handling, thanks to
416          * Wei Dai <weidai@eskimo.com> for pointing it out. */
417         if (l < c->Nl) /* overflow */
418                 c->Nh++;
419         c->Nh+=(len>>29);
420         c->Nl=l;
421
422         if (c->num != 0)
423                 {
424                 p=c->data;
425                 sw=c->num>>2;
426                 sc=c->num&0x03;
427
428                 if ((c->num+len) >= HASH_CBLOCK)
429                         {
430                         l=p[sw]; HOST_p_c2l(data,l,sc); p[sw++]=l;
431                         for (; sw<HASH_LBLOCK; sw++)
432                                 {
433                                 HOST_c2l(data,l); p[sw]=l;
434                                 }
435                         HASH_BLOCK_HOST_ORDER (c,p,1);
436                         len-=(HASH_CBLOCK-c->num);
437                         c->num=0;
438                         /* drop through and do the rest */
439                         }
440                 else
441                         {
442                         c->num+=len;
443                         if ((sc+len) < 4) /* ugly, add char's to a word */
444                                 {
445                                 l=p[sw]; HOST_p_c2l_p(data,l,sc,len); p[sw]=l;
446                                 }
447                         else
448                                 {
449                                 ew=(c->num>>2);
450                                 ec=(c->num&0x03);
451                                 l=p[sw]; HOST_p_c2l(data,l,sc); p[sw++]=l;
452                                 for (; sw < ew; sw++)
453                                         {
454                                         HOST_c2l(data,l); p[sw]=l;
455                                         }
456                                 if (ec)
457                                         {
458                                         HOST_c2l_p(data,l,ec); p[sw]=l;
459                                         }
460                                 }
461                         return;
462                         }
463                 }
464
465         sw=len/HASH_CBLOCK;
466         if (sw > 0)
467                 {
468 #if defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
469                 /*
470                  * Note that HASH_BLOCK_DATA_ORDER_ALIGNED gets defined
471                  * only if sizeof(HASH_LONG)==4.
472                  */
473                 if ((((unsigned long)data)%4) == 0)
474                         {
475                         /* data is properly aligned so that we can cast it: */
476                         HASH_BLOCK_DATA_ORDER_ALIGNED (c,(HASH_LONG *)data,sw);
477                         sw*=HASH_CBLOCK;
478                         data+=sw;
479                         len-=sw;
480                         }
481                 else
482 #if !defined(HASH_BLOCK_DATA_ORDER)
483                         while (sw--)
484                                 {
485                                 memcpy (p=c->data,data,HASH_CBLOCK);
486                                 HASH_BLOCK_DATA_ORDER_ALIGNED(c,p,1);
487                                 data+=HASH_CBLOCK;
488                                 len-=HASH_CBLOCK;
489                                 }
490 #endif
491 #endif
492 #if defined(HASH_BLOCK_DATA_ORDER)
493                         {
494                         HASH_BLOCK_DATA_ORDER(c,data,sw);
495                         sw*=HASH_CBLOCK;
496                         data+=sw;
497                         len-=sw;
498                         }
499 #endif
500                 }
501
502         if (len!=0)
503                 {
504                 p = c->data;
505                 c->num = len;
506                 ew=len>>2;      /* words to copy */
507                 ec=len&0x03;
508                 for (; ew; ew--,p++)
509                         {
510                         HOST_c2l(data,l); *p=l;
511                         }
512                 HOST_c2l_p(data,l,ec);
513                 *p=l;
514                 }
515         }
516
517
518 void HASH_TRANSFORM (HASH_CTX *c, const unsigned char *data)
519         {
520 #if defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
521         if ((((unsigned long)data)%4) == 0)
522                 /* data is properly aligned so that we can cast it: */
523                 HASH_BLOCK_DATA_ORDER_ALIGNED (c,(HASH_LONG *)data,1);
524         else
525 #if !defined(HASH_BLOCK_DATA_ORDER)
526                 {
527                 memcpy (c->data,data,HASH_CBLOCK);
528                 HASH_BLOCK_DATA_ORDER_ALIGNED (c,c->data,1);
529                 }
530 #endif
531 #endif
532 #if defined(HASH_BLOCK_DATA_ORDER)
533         HASH_BLOCK_DATA_ORDER (c,data,1);
534 #endif
535         }
536
537
538 void HASH_FINAL (unsigned char *md, HASH_CTX *c)
539         {
540         register HASH_LONG *p;
541         register unsigned long l;
542         register int i,j;
543         static const unsigned char end[4]={0x80,0x00,0x00,0x00};
544         const unsigned char *cp=end;
545
546         /* c->num should definitly have room for at least one more byte. */
547         p=c->data;
548         i=c->num>>2;
549         j=c->num&0x03;
550
551 #if 0
552         /* purify often complains about the following line as an
553          * Uninitialized Memory Read.  While this can be true, the
554          * following p_c2l macro will reset l when that case is true.
555          * This is because j&0x03 contains the number of 'valid' bytes
556          * already in p[i].  If and only if j&0x03 == 0, the UMR will
557          * occur but this is also the only time p_c2l will do
558          * l= *(cp++) instead of l|= *(cp++)
559          * Many thanks to Alex Tang <altitude@cic.net> for pickup this
560          * 'potential bug' */
561 #ifdef PURIFY
562         if (j==0) p[i]=0; /* Yeah, but that's not the way to fix it:-) */
563 #endif
564         l=p[i];
565 #else
566         l = (j==0) ? 0 : p[i];
567 #endif
568         HOST_p_c2l(cp,l,j); p[i++]=l; /* i is the next 'undefined word' */
569
570         if (i>(HASH_LBLOCK-2)) /* save room for Nl and Nh */
571                 {
572                 if (i<HASH_LBLOCK) p[i]=0;
573                 HASH_BLOCK_HOST_ORDER (c,p,1);
574                 i=0;
575                 }
576         for (; i<(HASH_LBLOCK-2); i++)
577                 p[i]=0;
578
579 #if   defined(DATA_ORDER_IS_BIG_ENDIAN)
580         p[HASH_LBLOCK-2]=c->Nh;
581         p[HASH_LBLOCK-1]=c->Nl;
582 #elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)
583         p[HASH_LBLOCK-2]=c->Nl;
584         p[HASH_LBLOCK-1]=c->Nh;
585 #endif
586         HASH_BLOCK_HOST_ORDER (c,p,1);
587
588 #ifndef HASH_MAKE_STRING
589 #error "HASH_MAKE_STRING must be defined!"
590 #else
591         HASH_MAKE_STRING(c,md);
592 #endif
593
594         c->num=0;
595         /* clear stuff, HASH_BLOCK may be leaving some stuff on the stack
596          * but I'm not worried :-)
597         memset((void *)c,0,sizeof(HASH_CTX));
598          */
599         }