1 /*
2 ** Write a 64-bit variable-length integer to memory starting at p[0].
3 ** The length of data write will be between 1 and 9 bytes. The number
4 ** of bytes written is returned.
5 **
6 ** A variable-length integer consists of the lower 7 bits of each byte
7 ** for all bytes that have the 8th bit set and one byte with the 8th
8 ** bit clear. Except, if we get to the 9th byte, it stores the full
9 ** 8 bits and is the last byte.
10 */
sqlite3PutVarint(unsigned char * p,u64 v)11 SQLITE_PRIVATE int sqlite3PutVarint(unsigned char *p, u64 v){
12 int i, j, n;
13 u8 buf[10];
14 if( v & (((u64)0xff000000)<<32) ){
15 p[8] = v;
16 v >>= 8;
17 for(i=7; i>=0; i--){
18 p[i] = (v & 0x7f) | 0x80;
19 v >>= 7;
20 }
21 return 9;
22 }
23 n = 0;
24 do{
25 buf[n++] = (v & 0x7f) | 0x80;
26 v >>= 7;
27 }while( v!=0 );
28 buf[0] &= 0x7f;
29 assert( n<=9 );
30 for(i=0, j=n-1; j>=0; j--, i++){
31 p[i] = buf[j];
32 }
33 return n;
34 }
35
36