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Simplification to sqlite3GetVarint32() to avoid confusing gcov.

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FossilOrigin-Name: 89862c51ad9715bedf5b029db484602e740f0db7404970d482ce503c1b9a0ed2
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drh
2023-10-19 13:35:22 +00:00
parent 11877c6ba4
commit 0588385799
3 changed files with 25 additions and 114 deletions
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125
src/util.c
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@@ -1367,121 +1367,32 @@ u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
** this function assumes the single-byte case has already been handled.
*/
u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
u32 a,b;
u64 v64;
u8 n;
/* The 1-byte case. Overwhelmingly the most common. Handled inline
** by the getVarin32() macro */
a = *p;
/* a: p0 (unmasked) */
#ifndef getVarint32
if (!(a&0x80))
{
/* Values between 0 and 127 */
*v = a;
return 1;
}
#endif
/* Assume that the single-byte case has already been handled by
** the getVarint32() macro */
assert( (p[0] & 0x80)!=0 );
/* The 2-byte case */
p++;
b = *p;
/* b: p1 (unmasked) */
if (!(b&0x80))
{
/* Values between 128 and 16383 */
a &= 0x7f;
a = a<<7;
*v = a | b;
if( (p[1] & 0x80)==0 ){
/* This is the two-byte case */
*v = ((p[0]&0x7f)<<7) | p[1];
return 2;
}
/* The 3-byte case */
p++;
a = a<<14;
a |= *p;
/* a: p0<<14 | p2 (unmasked) */
if (!(a&0x80))
{
/* Values between 16384 and 2097151 */
a &= (0x7f<<14)|(0x7f);
b &= 0x7f;
b = b<<7;
*v = a | b;
if( (p[2] & 0x80)==0 ){
/* This is the three-byte case */
*v = ((p[0]&0x7f)<<14) | ((p[1]&0x7f)<<7) | p[2];
return 3;
}
/* A 32-bit varint is used to store size information in btrees.
** Objects are rarely larger than 2MiB limit of a 3-byte varint.
** A 3-byte varint is sufficient, for example, to record the size
** of a 1048569-byte BLOB or string.
**
** We only unroll the first 1-, 2-, and 3- byte cases. The very
** rare larger cases can be handled by the slower 64-bit varint
** routine.
*/
#if 1
{
u64 v64;
u8 n;
n = sqlite3GetVarint(p-2, &v64);
assert( n>3 && n<=9 );
if( (v64 & SQLITE_MAX_U32)!=v64 ){
*v = 0xffffffff;
}else{
*v = (u32)v64;
}
return n;
}
#else
/* For following code (kept for historical record only) shows an
** unrolling for the 3- and 4-byte varint cases. This code is
** slightly faster, but it is also larger and much harder to test.
*/
p++;
b = b<<14;
b |= *p;
/* b: p1<<14 | p3 (unmasked) */
if (!(b&0x80))
{
/* Values between 2097152 and 268435455 */
b &= (0x7f<<14)|(0x7f);
a &= (0x7f<<14)|(0x7f);
a = a<<7;
*v = a | b;
return 4;
}
p++;
a = a<<14;
a |= *p;
/* a: p0<<28 | p2<<14 | p4 (unmasked) */
if (!(a&0x80))
{
/* Values between 268435456 and 34359738367 */
a &= SLOT_4_2_0;
b &= SLOT_4_2_0;
b = b<<7;
*v = a | b;
return 5;
}
/* We can only reach this point when reading a corrupt database
** file. In that case we are not in any hurry. Use the (relatively
** slow) general-purpose sqlite3GetVarint() routine to extract the
** value. */
{
u64 v64;
u8 n;
p -= 4;
n = sqlite3GetVarint(p, &v64);
assert( n>5 && n<=9 );
/* four or more bytes */
n = sqlite3GetVarint(p, &v64);
assert( n>3 && n<=9 );
if( (v64 & SQLITE_MAX_U32)!=v64 ){
*v = 0xffffffff;
}else{
*v = (u32)v64;
return n;
}
#endif
return n;
}
/*