How to make simplest possible autorange Capacitance meter

1#include <U8g2lib.h>
2#include <Capacitor.h>
3
4U8G2_ST7565_ERC12864_1_4W_SW_SPI u8g2 ( U8G2_R0, /* scl=*/  13 , /* si=*/  11 , /* cs=*/  10 , /* rs=*/  9 , /* rse=*/  8 ) ;
5
6Capacitor cap1(7,A2);
7
8int X1,C; //resistance value
9byte  f_ic, xp;
10char R1_str[3];
11char R_str[4];
12float tau1;   
13unsigned long T1, T2, tau;
14
15void setup() {
16  Serial.begin(9600);
17   u8g2.begin();
18   u8g2.setContrast(35);
19}
20
21   
22    void loop() {
23 // Serial.println(cap1.Measure());  // Measure the capacitance (in pF), print to Serial Monitor
24 // delay(1000);                     // Wait for 1 second, then repeat
25  Pomiar_C();
26}  
27
28
29void Pomiar_C(){
30  Cyfry();
31  char C_str[4];
32  sprintf(C_str,"%d", X1);
33  u8g2.firstPage();
34  do {
35
36  u8g2.drawFrame(0,0,128,64);  
37  u8g2.drawRFrame(2,2,124,60,3);
38    
39     u8g2.setFont(u8g2_font_10x20_tr);
40     u8g2.drawStr(20, 18, "Capacity:");        
41     if (f_ic > 6) { 
42        u8g2.setFont(u8g2_font_fub25_t_symbol);
43        u8g2.drawGlyph(80,52,956);               //symbol u
44     }   
45     u8g2.setFont(u8g2_font_fub25_tr);
46     u8g2.drawStr(xp, 52, C_str);
47     if (f_ic < 7) {u8g2.drawStr(76, 52, "n");}
48     if (f_ic < 4) {u8g2.drawStr(76, 52, "p");}
49     u8g2.drawStr(100, 52, "F"); 
50     if (f_ic == 1 or f_ic == 4 or f_ic == 7) {
51         u8g2.drawStr(28, 52, "."); 
52         u8g2.drawStr(40, 52, R1_str); 
53     }    
54  } while ( u8g2.nextPage() );
55  delay(500);
56}
57
58void Cyfry(){
59//  if (P1 == LOW) {tau1 = tau/2.329;}    
60//  if (P2 == LOW) {tau1 = tau/350;}
61 // if (P3 == LOW) {tau1 = cap1.Measure();}
62
63 tau1 = cap1.Measure();
64  //obliczenie ilości cyfr wartości
65  if (tau1 >= 1 && tau1 <10) {                  
66     X1 = tau1;
67     int X2 = 10 * (tau1 - X1);
68  sprintf(R1_str,"%d", X2);
69     f_ic = 1;
70     xp = 10;     
71  }
72  if (tau1 >= 10 && tau1 <100) {            
73     X1 = tau1;
74     f_ic = 2;
75     xp = 32;
76  }
77  if (tau1 >= 100 && tau1 <1000) {         
78     X1 = tau1;
79     f_ic = 3;
80     xp = 10;
81  }
82  if (tau1/1000 >= 1 && tau1/1000 <10) {        
83     X1 = int(tau1/1000);
84     f_ic = 4;
85     xp = 10;
86     int X2 = 10 * (tau1/1000 - X1);
87   sprintf(R1_str,"%d", X2);
88  }
89  if (tau1/10000 >= 1 && tau1/10000 <10) {      
90     X1 = int(tau1/1000);
91     f_ic = 5;
92     xp = 32;
93  }
94  if (tau1/100000 >= 1 && tau1/100000 <10) {    
95     X1 = int(tau1/1000);
96     f_ic = 6;
97     xp = 10;
98  }
99  if (tau1/1000000 >= 1 && tau1/1000000 <10) {  
100     X1 = int(tau1/1000000);
101     f_ic = 7;
102     xp = 10;
103     
104     int X2 = 10 * (tau1/1000000 - X1);
105   sprintf(R1_str,"%d", X2);
106  }
107   if (tau1/10000000 >= 1 && tau1/10000000 <10) {  
108     X1 = int(tau1/1000000);
109     f_ic = 8;
110     xp = 30;
111   }
112}