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-rw-r--r--src/util.c125
1 files changed, 18 insertions, 107 deletions
diff --git a/src/util.c b/src/util.c
index 58591590d..e9c7cccb0 100644
--- a/src/util.c
+++ b/src/util.c
@@ -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;
}
/*