Open source ADC read function

/*

* Based on MikroElectronika ADC on LCD example

* Uses self written ADC_Read function

*/

unsigned char ch;
unsigned int adc_rd;
char *text;
long tlong;

sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;

unsigned adc_read2(char channel)
{

switch (channel) {
case 0: {
ADCON0.CHS0 = 0;
ADCON0.CHS1 = 0;
ADCON0.CHS2 = 0;
ADCON0.CHS3 = 0;
}
case 1: {
ADCON0.CHS0 = 1;
ADCON0.CHS1 = 0;
ADCON0.CHS2 = 0;
ADCON0.CHS3 = 0;
}
case 2: {
ADCON0.CHS0 = 0;
ADCON0.CHS1 = 1;
ADCON0.CHS2 = 0;
ADCON0.CHS3 = 0;
}
case 3: {
ADCON0.CHS0 = 1;
ADCON0.CHS1 = 1;
ADCON0.CHS2 = 0;
ADCON0.CHS3 = 0;
}
case 4: {
ADCON0.CHS0 = 0;
ADCON0.CHS1 = 0;
ADCON0.CHS2 = 1;
ADCON0.CHS3 = 0;
}

}

ADCON0.GO_DONE = 1; // start conversion
while (ADCON0.GO_DONE); // wait for conversion
return (ADRESH << 8) + ADRESL; // return value
}

void main() {
INTCON = 0; // disable all interrupts
ANSEL = 0x04; // Configure AN2 pin as analog input
TRISA = 0x04;
ANSELH = 0; // Configure other AN pins as digital I/O

ADCON1.VCFG0 = 0; // set internal
ADCON1.VCFG1 = 0;
ADCON0.ADCS0 = 1; // use Vdd as reference
ADCON0.ADCS1 = 0; // use Vcc as reference
ADCON1.ADFM = 1; // result is right Justified
ADCON0.ADON = 1; // enable A/D converter

Lcd_Init();
LCD_Cmd(_LCD_CURSOR_OFF); // send command to LCD (cursor off)
LCD_Cmd(_LCD_CLEAR); // send command to LCD (clear LCD)

text = "mikroElektronika"; // assign text to string
LCD_Out(1,1,text); // print string a on LCD, 1st row, 1st column
text = "LCD example"; // assign text to string
LCD_Out(2,1,text); // print string a on LCD, 2nd row, 1st column

ADCON1 = 0x82; // configure VDD as Vref, and analog channels
TRISA = 0xFF; // designate PORTA as input
Delay_ms(2000);
text = "voltage:"; // assign text to string
while (1) {
// let's use our open source function
    adc_rd = ADC_read2(2); // get ADC value from 2nd channel
    LCD_Out(2,1,text); // print string a on LCD, 2nd row, 1st column

    tlong = (long)adc_rd * 5000; // covert adc reading to milivolts
    tlong = tlong / 1023; // 0..1023 -> 0-5000mV

    ch = tlong / 1000; // extract volts digit
    LCD_Chr(2,9,48+ch); // write ASCII digit at 2nd row, 9th column
    LCD_Chr_CP('.');

    ch = (tlong / 100) % 10; // extract 0.1 volts digit
    LCD_Chr_CP(48+ch); // write ASCII digit at cursor point

    ch = (tlong / 10) % 10; // extract 0.01 volts digit
    LCD_Chr_CP(48+ch); // write ASCII digit at cursor point

    ch = tlong % 10; // extract 0.001 volts digit
    LCD_Chr_CP(48+ch); // write ASCII digit at cursor point
    LCD_Chr_CP('V');

    Delay_ms(1);
}
}