Add the sqlite3Int64ToText() routine and use it to convert integers to text,

as it is much faster than the generic text formatter.

FossilOrigin-Name: 14eed318aa9e6e16d1aa13a9f34e3822aa135c39ba06c77df7743509fed6c95e

src/util.c

@@ -595,6 +595,30 @@ do_atof_calc:
 #pragma warning(default : 4756)
 #endif
 
+/*
+** Render an signed 64-bit integer as text.  Store the result in zOut[].
+**
+** The caller must ensure that zOut[] is at least 21 bytes in size.
+*/
+void sqlite3Int64ToText(i64 v, char *zOut){
+  int i;
+  u64 x;
+  char zTemp[22];
+  if( v<0 ){
+    x = (v==SMALLEST_INT64) ? ((u64)1)<<63 : -v;
+  }else{
+    x = v;
+  }
+  i = sizeof(zTemp)-2;
+  zTemp[sizeof(zTemp)-1] = 0;
+  do{
+    zTemp[i--] = (x%10) + '0';
+    x = x/10;
+  }while( x );
+  if( v<0 ) zTemp[i--] = '-';
+  memcpy(zOut, &zTemp[i+1], sizeof(zTemp)-1-i);
+}
+
 /*
 ** Compare the 19-character string zNum against the text representation
 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive