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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

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Overview
Comment:Make use of htonl() and __builtin_bswap32() for faster implementations of sqlite3Get4byte() and sqlite3Put4byte().
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SHA1: bc27ebd7f73e9fc8e00da6ec82632e439fcce812
User & Date: drh 2015-06-30 12:47:09
Context
2015-06-30
13:28
Remove the use of htonl() in the previous check-in due to linkage issues. Add the get2byteAligned() macro and use it for access to the cell offsets on btree pages for about a 1% performance gain. check-in: 79ff36b7 user: drh tags: bswap-functions
12:47
Make use of htonl() and __builtin_bswap32() for faster implementations of sqlite3Get4byte() and sqlite3Put4byte(). check-in: bc27ebd7 user: drh tags: bswap-functions
11:07
Change an unreachable branch into an assert() in sqlite3PagerAcquire() and optimize sqlite3PcacheOpenSavepoint() by factoring out rarely used code into a subroutine. check-in: b406b20e user: drh tags: trunk
Changes
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Changes to src/util.c.

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}


/*
** Read or write a four-byte big-endian integer value.
*/
u32 sqlite3Get4byte(const u8 *p){













  testcase( p[0]&0x80 );
  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];

}
void sqlite3Put4byte(unsigned char *p, u32 v){









  p[0] = (u8)(v>>24);
  p[1] = (u8)(v>>16);
  p[2] = (u8)(v>>8);
  p[3] = (u8)v;

}



/*
** Translate a single byte of Hex into an integer.
** This routine only works if h really is a valid hexadecimal







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}


/*
** Read or write a four-byte big-endian integer value.
*/
u32 sqlite3Get4byte(const u8 *p){
#if SQLITE_BYTEORDER==4321
  u32 x;
  memcpy(&x,p,4);
  return x;
#elif defined(_MSC_VER)
  u32 x;
  memcpy(&x,p,4);
  return htonl(x);
#elif SQLITE_BYTEORDER==1234 && defined(__GNUC__)
  u32 x;
  memcpy(&x,p,4);
  return __builtin_bswap32(x);
#else
  testcase( p[0]&0x80 );
  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
#endif
}
void sqlite3Put4byte(unsigned char *p, u32 v){
#if SQLITE_BYTEORDER==4321
  memcpy(p,&v,4);
#elif defined(_MSC_VER)
  u32 x = htonl(v);
  memcpy(&x,p,4);
#elif SQLITE_BYTEORDER==1234 && defined(__GNUC__)
  u32 x = __builtin_bswap32(v);
  memcpy(p,&x,4);
#else
  p[0] = (u8)(v>>24);
  p[1] = (u8)(v>>16);
  p[2] = (u8)(v>>8);
  p[3] = (u8)v;
#endif
}



/*
** Translate a single byte of Hex into an integer.
** This routine only works if h really is a valid hexadecimal