36 lines · c
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 number4** of bytes written is returned.5**6** A variable-length integer consists of the lower 7 bits of each byte7** for all bytes that have the 8th bit set and one byte with the 8th8** bit clear. Except, if we get to the 9th byte, it stores the full9** 8 bits and is the last byte.10*/11SQLITE_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