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md32_common.h

/* crypto/md32_common.h */
/* ====================================================================
 * Copyright (c) 1999-2002 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

/*
 * This is a generic 32 bit "collector" for message digest algorithms.
 * Whenever needed it collects input character stream into chunks of
 * 32 bit values and invokes a block function that performs actual hash
 * calculations.
 *
 * Porting guide.
 *
 * Obligatory macros:
 *
 * DATA_ORDER_IS_BIG_ENDIAN or DATA_ORDER_IS_LITTLE_ENDIAN
 *    this macro defines byte order of input stream.
 * HASH_CBLOCK
 *    size of a unit chunk HASH_BLOCK operates on.
 * HASH_LONG
 *    has to be at lest 32 bit wide, if it's wider, then
 *    HASH_LONG_LOG2 *has to* be defined along
 * HASH_CTX
 *    context structure that at least contains following
 *    members:
 *          typedef struct {
 *                ...
 *                HASH_LONG   Nl,Nh;
 *                HASH_LONG   data[HASH_LBLOCK];
 *                unsigned int      num;
 *                ...
 *                } HASH_CTX;
 * HASH_UPDATE
 *    name of "Update" function, implemented here.
 * HASH_TRANSFORM
 *    name of "Transform" function, implemented here.
 * HASH_FINAL
 *    name of "Final" function, implemented here.
 * HASH_BLOCK_HOST_ORDER
 *    name of "block" function treating *aligned* input message
 *    in host byte order, implemented externally.
 * HASH_BLOCK_DATA_ORDER
 *    name of "block" function treating *unaligned* input message
 *    in original (data) byte order, implemented externally (it
 *    actually is optional if data and host are of the same
 *    "endianess").
 * HASH_MAKE_STRING
 *    macro convering context variables to an ASCII hash string.
 *
 * Optional macros:
 *
 * B_ENDIAN or L_ENDIAN
 *    defines host byte-order.
 * HASH_LONG_LOG2
 *    defaults to 2 if not states otherwise.
 * HASH_LBLOCK
 *    assumed to be HASH_CBLOCK/4 if not stated otherwise.
 * HASH_BLOCK_DATA_ORDER_ALIGNED
 *    alternative "block" function capable of treating
 *    aligned input message in original (data) order,
 *    implemented externally.
 *
 * MD5 example:
 *
 *    #define DATA_ORDER_IS_LITTLE_ENDIAN
 *
 *    #define HASH_LONG       MD5_LONG
 *    #define HASH_LONG_LOG2        MD5_LONG_LOG2
 *    #define HASH_CTX        MD5_CTX
 *    #define HASH_CBLOCK           MD5_CBLOCK
 *    #define HASH_LBLOCK           MD5_LBLOCK
 *    #define HASH_UPDATE           MD5_Update
 *    #define HASH_TRANSFORM        MD5_Transform
 *    #define HASH_FINAL            MD5_Final
 *    #define HASH_BLOCK_HOST_ORDER md5_block_host_order
 *    #define HASH_BLOCK_DATA_ORDER md5_block_data_order
 *
 *                            <appro@fy.chalmers.se>
 */

#if !defined(DATA_ORDER_IS_BIG_ENDIAN) && !defined(DATA_ORDER_IS_LITTLE_ENDIAN)
#error "DATA_ORDER must be defined!"
#endif

#ifndef HASH_CBLOCK
#error "HASH_CBLOCK must be defined!"
#endif
#ifndef HASH_LONG
#error "HASH_LONG must be defined!"
#endif
#ifndef HASH_CTX
#error "HASH_CTX must be defined!"
#endif

#ifndef HASH_UPDATE
#error "HASH_UPDATE must be defined!"
#endif
#ifndef HASH_TRANSFORM
#error "HASH_TRANSFORM must be defined!"
#endif
#ifndef HASH_FINAL
#error "HASH_FINAL must be defined!"
#endif

#ifndef HASH_BLOCK_HOST_ORDER
#error "HASH_BLOCK_HOST_ORDER must be defined!"
#endif

#if 0
/*
 * Moved below as it's required only if HASH_BLOCK_DATA_ORDER_ALIGNED
 * isn't defined.
 */
#ifndef HASH_BLOCK_DATA_ORDER
#error "HASH_BLOCK_DATA_ORDER must be defined!"
#endif
#endif

#ifndef HASH_LBLOCK
#define HASH_LBLOCK     (HASH_CBLOCK/4)
#endif

#ifndef HASH_LONG_LOG2
#define HASH_LONG_LOG2  2
#endif

/*
 * Engage compiler specific rotate intrinsic function if available.
 */
#undef ROTATE
#ifndef PEDANTIC
# if defined(_MSC_VER) || defined(__ICC)
#  define ROTATE(a,n)   _lrotl(a,n)
# elif defined(__MWERKS__)
#  if defined(__POWERPC__)
#   define ROTATE(a,n)  __rlwinm(a,n,0,31)
#  elif defined(__MC68K__)
    /* Motorola specific tweak. <appro@fy.chalmers.se> */
#   define ROTATE(a,n)  ( n<24 ? __rol(a,n) : __ror(a,32-n) )
#  else
#   define ROTATE(a,n)  __rol(a,n)
#  endif
# elif defined(__GNUC__) && __GNUC__>=2 && !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM)
  /*
   * Some GNU C inline assembler templates. Note that these are
   * rotates by *constant* number of bits! But that's exactly
   * what we need here...
   *                          <appro@fy.chalmers.se>
   */
#  if defined(__i386) || defined(__i386__) || defined(__x86_64) || defined(__x86_64__)
#   define ROTATE(a,n)  ({ register unsigned int ret; \
                        asm (             \
                        "roll %1,%0"            \
                        : "=r"(ret)       \
                        : "I"(n), "0"(a)  \
                        : "cc");          \
                     ret;                       \
                  })
#  elif defined(__powerpc) || defined(__ppc__) || defined(__powerpc64__)
#   define ROTATE(a,n)  ({ register unsigned int ret; \
                        asm (             \
                        "rlwinm %0,%1,%2,0,31"  \
                        : "=r"(ret)       \
                        : "r"(a), "I"(n));      \
                     ret;                       \
                  })
#  endif
# endif
#endif /* PEDANTIC */

#if HASH_LONG_LOG2==2   /* Engage only if sizeof(HASH_LONG)== 4 */
/* A nice byte order reversal from Wei Dai <weidai@eskimo.com> */
#ifdef ROTATE
/* 5 instructions with rotate instruction, else 9 */
#define REVERSE_FETCH32(a,l)  (                             \
            l=*(const HASH_LONG *)(a),                      \
            ((ROTATE(l,8)&0x00FF00FF)|(ROTATE((l&0x00FF00FF),24)))      \
                        )
#else
/* 6 instructions with rotate instruction, else 8 */
#define REVERSE_FETCH32(a,l)  (                       \
            l=*(const HASH_LONG *)(a),                \
            l=(((l>>8)&0x00FF00FF)|((l&0x00FF00FF)<<8)),    \
            ROTATE(l,16)                              \
                        )
/*
 * Originally the middle line started with l=(((l&0xFF00FF00)>>8)|...
 * It's rewritten as above for two reasons:
 *    - RISCs aren't good at long constants and have to explicitely
 *      compose 'em with several (well, usually 2) instructions in a
 *      register before performing the actual operation and (as you
 *      already realized:-) having same constant should inspire the
 *      compiler to permanently allocate the only register for it;
 *    - most modern CPUs have two ALUs, but usually only one has
 *      circuitry for shifts:-( this minor tweak inspires compiler
 *      to schedule shift instructions in a better way...
 *
 *                      <appro@fy.chalmers.se>
 */
#endif
#endif

#ifndef ROTATE
#define ROTATE(a,n)     (((a)<<(n))|(((a)&0xffffffff)>>(32-(n))))
#endif

/*
 * Make some obvious choices. E.g., HASH_BLOCK_DATA_ORDER_ALIGNED
 * and HASH_BLOCK_HOST_ORDER ought to be the same if input data
 * and host are of the same "endianess". It's possible to mask
 * this with blank #define HASH_BLOCK_DATA_ORDER though...
 *
 *                      <appro@fy.chalmers.se>
 */
#if defined(B_ENDIAN)
#  if defined(DATA_ORDER_IS_BIG_ENDIAN)
#    if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED) && HASH_LONG_LOG2==2
#      define HASH_BLOCK_DATA_ORDER_ALIGNED     HASH_BLOCK_HOST_ORDER
#    endif
#  endif
#elif defined(L_ENDIAN)
#  if defined(DATA_ORDER_IS_LITTLE_ENDIAN)
#    if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED) && HASH_LONG_LOG2==2
#      define HASH_BLOCK_DATA_ORDER_ALIGNED     HASH_BLOCK_HOST_ORDER
#    endif
#  endif
#endif

#if !defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
#ifndef HASH_BLOCK_DATA_ORDER
#error "HASH_BLOCK_DATA_ORDER must be defined!"
#endif
#endif

#if defined(DATA_ORDER_IS_BIG_ENDIAN)

#ifndef PEDANTIC
# if defined(__GNUC__) && __GNUC__>=2 && !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM)
#  if ((defined(__i386) || defined(__i386__)) && !defined(I386_ONLY)) || \
      (defined(__x86_64) || defined(__x86_64__))
    /*
     * This gives ~30-40% performance improvement in SHA-256 compiled
     * with gcc [on P4]. Well, first macro to be frank. We can pull
     * this trick on x86* platforms only, because these CPUs can fetch
     * unaligned data without raising an exception.
     */
#   define HOST_c2l(c,l)      ({ unsigned int r=*((const unsigned int *)(c)); \
                           asm ("bswapl %0":"=r"(r):"0"(r));      \
                           (c)+=4; (l)=r;             })
#   define HOST_l2c(l,c)      ({ unsigned int r=(l);              \
                           asm ("bswapl %0":"=r"(r):"0"(r));      \
                           *((unsigned int *)(c))=r; (c)+=4; r;   })
#  endif
# endif
#endif

#ifndef HOST_c2l
#define HOST_c2l(c,l)   (l =(((unsigned long)(*((c)++)))<<24),          \
                   l|=(((unsigned long)(*((c)++)))<<16),          \
                   l|=(((unsigned long)(*((c)++)))<< 8),          \
                   l|=(((unsigned long)(*((c)++)))    ),          \
                   l)
#endif
#define HOST_p_c2l(c,l,n)     {                             \
                  switch (n) {                              \
                  case 0: l =((unsigned long)(*((c)++)))<<24;     \
                  case 1: l|=((unsigned long)(*((c)++)))<<16;     \
                  case 2: l|=((unsigned long)(*((c)++)))<< 8;     \
                  case 3: l|=((unsigned long)(*((c)++)));         \
                        } }
#define HOST_p_c2l_p(c,l,sc,len) {                          \
                  switch (sc) {                             \
                  case 0: l =((unsigned long)(*((c)++)))<<24;     \
                        if (--len == 0) break;              \
                  case 1: l|=((unsigned long)(*((c)++)))<<16;     \
                        if (--len == 0) break;              \
                  case 2: l|=((unsigned long)(*((c)++)))<< 8;     \
                        } }
/* NOTE the pointer is not incremented at the end of this */
#define HOST_c2l_p(c,l,n)     {                             \
                  l=0; (c)+=n;                              \
                  switch (n) {                              \
                  case 3: l =((unsigned long)(*(--(c))))<< 8;     \
                  case 2: l|=((unsigned long)(*(--(c))))<<16;     \
                  case 1: l|=((unsigned long)(*(--(c))))<<24;     \
                        } }
#ifndef HOST_l2c
#define HOST_l2c(l,c)   (*((c)++)=(unsigned char)(((l)>>24)&0xff),      \
                   *((c)++)=(unsigned char)(((l)>>16)&0xff),      \
                   *((c)++)=(unsigned char)(((l)>> 8)&0xff),      \
                   *((c)++)=(unsigned char)(((l)    )&0xff),      \
                   l)
#endif

#elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)

#if defined(__i386) || defined(__i386__) || defined(__x86_64) || defined(__x86_64__)
# ifndef B_ENDIAN
   /* See comment in DATA_ORDER_IS_BIG_ENDIAN section. */
#  define HOST_c2l(c,l) ((l)=*((const unsigned int *)(c)), (c)+=4, l)
#  define HOST_l2c(l,c) (*((unsigned int *)(c))=(l), (c)+=4, l)
# endif
#endif

#ifndef HOST_c2l
#define HOST_c2l(c,l)   (l =(((unsigned long)(*((c)++)))    ),          \
                   l|=(((unsigned long)(*((c)++)))<< 8),          \
                   l|=(((unsigned long)(*((c)++)))<<16),          \
                   l|=(((unsigned long)(*((c)++)))<<24),          \
                   l)
#endif
#define HOST_p_c2l(c,l,n)     {                             \
                  switch (n) {                              \
                  case 0: l =((unsigned long)(*((c)++)));         \
                  case 1: l|=((unsigned long)(*((c)++)))<< 8;     \
                  case 2: l|=((unsigned long)(*((c)++)))<<16;     \
                  case 3: l|=((unsigned long)(*((c)++)))<<24;     \
                        } }
#define HOST_p_c2l_p(c,l,sc,len) {                          \
                  switch (sc) {                             \
                  case 0: l =((unsigned long)(*((c)++)));         \
                        if (--len == 0) break;              \
                  case 1: l|=((unsigned long)(*((c)++)))<< 8;     \
                        if (--len == 0) break;              \
                  case 2: l|=((unsigned long)(*((c)++)))<<16;     \
                        } }
/* NOTE the pointer is not incremented at the end of this */
#define HOST_c2l_p(c,l,n)     {                             \
                  l=0; (c)+=n;                              \
                  switch (n) {                              \
                  case 3: l =((unsigned long)(*(--(c))))<<16;     \
                  case 2: l|=((unsigned long)(*(--(c))))<< 8;     \
                  case 1: l|=((unsigned long)(*(--(c))));         \
                        } }
#ifndef HOST_l2c
#define HOST_l2c(l,c)   (*((c)++)=(unsigned char)(((l)    )&0xff),      \
                   *((c)++)=(unsigned char)(((l)>> 8)&0xff),      \
                   *((c)++)=(unsigned char)(((l)>>16)&0xff),      \
                   *((c)++)=(unsigned char)(((l)>>24)&0xff),      \
                   l)
#endif

#endif

/*
 * Time for some action:-)
 */

int HASH_UPDATE (HASH_CTX *c, const void *data_, size_t len)
      {
      const unsigned char *data=data_;
      register HASH_LONG * p;
      register HASH_LONG l;
      size_t sw,sc,ew,ec;

      if (len==0) return 1;

      l=(c->Nl+(((HASH_LONG)len)<<3))&0xffffffffUL;
      /* 95-05-24 eay Fixed a bug with the overflow handling, thanks to
       * Wei Dai <weidai@eskimo.com> for pointing it out. */
      if (l < c->Nl) /* overflow */
            c->Nh++;
      c->Nh+=(len>>29); /* might cause compiler warning on 16-bit */
      c->Nl=l;

      if (c->num != 0)
            {
            p=c->data;
            sw=c->num>>2;
            sc=c->num&0x03;

            if ((c->num+len) >= HASH_CBLOCK)
                  {
                  l=p[sw]; HOST_p_c2l(data,l,sc); p[sw++]=l;
                  for (; sw<HASH_LBLOCK; sw++)
                        {
                        HOST_c2l(data,l); p[sw]=l;
                        }
                  HASH_BLOCK_HOST_ORDER (c,p,1);
                  len-=(HASH_CBLOCK-c->num);
                  c->num=0;
                  /* drop through and do the rest */
                  }
            else
                  {
                  c->num+=(unsigned int)len;
                  if ((sc+len) < 4) /* ugly, add char's to a word */
                        {
                        l=p[sw]; HOST_p_c2l_p(data,l,sc,len); p[sw]=l;
                        }
                  else
                        {
                        ew=(c->num>>2);
                        ec=(c->num&0x03);
                        if (sc)
                              l=p[sw];
                        HOST_p_c2l(data,l,sc);
                        p[sw++]=l;
                        for (; sw < ew; sw++)
                              {
                              HOST_c2l(data,l); p[sw]=l;
                              }
                        if (ec)
                              {
                              HOST_c2l_p(data,l,ec); p[sw]=l;
                              }
                        }
                  return 1;
                  }
            }

      sw=len/HASH_CBLOCK;
      if (sw > 0)
            {
#if defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
            /*
             * Note that HASH_BLOCK_DATA_ORDER_ALIGNED gets defined
             * only if sizeof(HASH_LONG)==4.
             */
            if ((((size_t)data)%4) == 0)
                  {
                  /* data is properly aligned so that we can cast it: */
                  HASH_BLOCK_DATA_ORDER_ALIGNED (c,(const HASH_LONG *)data,sw);
                  sw*=HASH_CBLOCK;
                  data+=sw;
                  len-=sw;
                  }
            else
#if !defined(HASH_BLOCK_DATA_ORDER)
                  while (sw--)
                        {
                        memcpy (p=c->data,data,HASH_CBLOCK);
                        HASH_BLOCK_DATA_ORDER_ALIGNED(c,p,1);
                        data+=HASH_CBLOCK;
                        len-=HASH_CBLOCK;
                        }
#endif
#endif
#if defined(HASH_BLOCK_DATA_ORDER)
                  {
                  HASH_BLOCK_DATA_ORDER(c,data,sw);
                  sw*=HASH_CBLOCK;
                  data+=sw;
                  len-=sw;
                  }
#endif
            }

      if (len!=0)
            {
            p = c->data;
            c->num = len;
            ew=len>>2;  /* words to copy */
            ec=len&0x03;
            for (; ew; ew--,p++)
                  {
                  HOST_c2l(data,l); *p=l;
                  }
            HOST_c2l_p(data,l,ec);
            *p=l;
            }
      return 1;
      }


void HASH_TRANSFORM (HASH_CTX *c, const unsigned char *data)
      {
#if defined(HASH_BLOCK_DATA_ORDER_ALIGNED)
      if ((((size_t)data)%4) == 0)
            /* data is properly aligned so that we can cast it: */
            HASH_BLOCK_DATA_ORDER_ALIGNED (c,(const HASH_LONG *)data,1);
      else
#if !defined(HASH_BLOCK_DATA_ORDER)
            {
            memcpy (c->data,data,HASH_CBLOCK);
            HASH_BLOCK_DATA_ORDER_ALIGNED (c,c->data,1);
            }
#endif
#endif
#if defined(HASH_BLOCK_DATA_ORDER)
      HASH_BLOCK_DATA_ORDER (c,data,1);
#endif
      }


int HASH_FINAL (unsigned char *md, HASH_CTX *c)
      {
      register HASH_LONG *p;
      register unsigned long l;
      register int i,j;
      static const unsigned char end[4]={0x80,0x00,0x00,0x00};
      const unsigned char *cp=end;

      /* c->num should definitly have room for at least one more byte. */
      p=c->data;
      i=c->num>>2;
      j=c->num&0x03;

#if 0
      /* purify often complains about the following line as an
       * Uninitialized Memory Read.  While this can be true, the
       * following p_c2l macro will reset l when that case is true.
       * This is because j&0x03 contains the number of 'valid' bytes
       * already in p[i].  If and only if j&0x03 == 0, the UMR will
       * occur but this is also the only time p_c2l will do
       * l= *(cp++) instead of l|= *(cp++)
       * Many thanks to Alex Tang <altitude@cic.net> for pickup this
       * 'potential bug' */
#ifdef PURIFY
      if (j==0) p[i]=0; /* Yeah, but that's not the way to fix it:-) */
#endif
      l=p[i];
#else
      l = (j==0) ? 0 : p[i];
#endif
      HOST_p_c2l(cp,l,j); p[i++]=l; /* i is the next 'undefined word' */

      if (i>(HASH_LBLOCK-2)) /* save room for Nl and Nh */
            {
            if (i<HASH_LBLOCK) p[i]=0;
            HASH_BLOCK_HOST_ORDER (c,p,1);
            i=0;
            }
      for (; i<(HASH_LBLOCK-2); i++)
            p[i]=0;

#if   defined(DATA_ORDER_IS_BIG_ENDIAN)
      p[HASH_LBLOCK-2]=c->Nh;
      p[HASH_LBLOCK-1]=c->Nl;
#elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)
      p[HASH_LBLOCK-2]=c->Nl;
      p[HASH_LBLOCK-1]=c->Nh;
#endif
      HASH_BLOCK_HOST_ORDER (c,p,1);

#ifndef HASH_MAKE_STRING
#error "HASH_MAKE_STRING must be defined!"
#else
      HASH_MAKE_STRING(c,md);
#endif

      c->num=0;
      /* clear stuff, HASH_BLOCK may be leaving some stuff on the stack
       * but I'm not worried :-)
      OPENSSL_cleanse((void *)c,sizeof(HASH_CTX));
       */
      return 1;
      }

#ifndef MD32_REG_T
#define MD32_REG_T long
/*
 * This comment was originaly written for MD5, which is why it
 * discusses A-D. But it basically applies to all 32-bit digests,
 * which is why it was moved to common header file.
 *
 * In case you wonder why A-D are declared as long and not
 * as MD5_LONG. Doing so results in slight performance
 * boost on LP64 architectures. The catch is we don't
 * really care if 32 MSBs of a 64-bit register get polluted
 * with eventual overflows as we *save* only 32 LSBs in
 * *either* case. Now declaring 'em long excuses the compiler
 * from keeping 32 MSBs zeroed resulting in 13% performance
 * improvement under SPARC Solaris7/64 and 5% under AlphaLinux.
 * Well, to be honest it should say that this *prevents* 
 * performance degradation.
 *                      <appro@fy.chalmers.se>
 * Apparently there're LP64 compilers that generate better
 * code if A-D are declared int. Most notably GCC-x86_64
 * generates better code.
 *                      <appro@fy.chalmers.se>
 */
#endif

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