SDCC Ejemplo 4 ADC

typedef unsigned int word;
word at 0x2007 CONFIG = _HS_OSC & _WDT_OFF & _PWRTE_ON & _BODEN_ON & _LVP_OFF & _CPD_OFF & _WRT_OFF & _DEBUG_OFF & _CP_OFF;


int LeerADC(int);

void main() {
unsigned int aux;
ADCON1=0b00000001; // Vref+ AN3
TRISA=0b11111111;
TRISB=0b00000000;
while(1){
aux = LeerADC(1);
PORTB = aux;
}
}


int LeerADC (int c){
switch(c) {
case 1:
ADCON0=0b01000001; //RA0 AN0
break;
case 2:
ADCON0=0b01001001; //RA1 AN1
break;
case 3:
ADCON0=0b01010001; //RA2 AN2
break;
case 4:
ADCON0=0b01100001; //RA5 AN4
break;
}
GO=1;
while(GO==0);
return ADRESH;
}