ADS7804 AD conversion program

#include 
#include 
#define uint unsigned int 
#define uchar unsigned char 
#define N 128 /*define sampling length, such as 128 points*/ 

sbit BYTE=P1^0; 
sbit RC=P1^1; 
sbit BUSY=P1^2; /*Define special bits*/ 
int xdata array[128]; /*Define a signed integer of length N in the external memory*/ 
int ADS7804(void); 

int ADS7804(void) 
{ 
uint ul,uh;int u; 
RC=0; /*Low level, enter conversion mode*/ 
ul=XBYTE[0xffff]; /*Generate read pulse, start A/D conversion*/ 
while(BUSY==0); /*Wait for conversion to complete*/ 
RC=1;BYTE=0; /*Enter read mode, select low byte*/ 
ul=XBYTE[0xffff]; /*Read the low 8 bits of the conversion result*/ 
BYTE=1; /*Select the high byte*/ 
uh=XBYTE[0xffff]&0x0f; /*Read the high 4 bits of the conversion result*/ 
u=uh*256+ul; /*Get a 12-bit conversion result*/ 
if(u>=0x0800) 
u=u|0xf000; /*If it is a negative value, sign extension*/ 
return(u); /*Return the conversion result*/ 
} 

void DAQ(uint interval) 
{ 
uchar th,tl; 
uint i; 
interval=interval-5; /*Subtract the time 5μs for clearing TF0 and loading the initial value of the count*/ 
th=255-(interval/256); 
tl=255-(interval%256); /*Calculate the initial value of the count*/ 
TMOD=0x01; /*Timer 0, mode 1 */ 
TH0=th; TL0=tl; /*Load the initial value of the count*/ 
TR0=1; /*Start timing*/ 
for(i=0;i{  
do{}while(!TF0); /*Query and wait for TF0 reset*/ 
TF0=0; /*Clear overflow flag*/ 
TH0=th; TL0=tl; /*Load initial count value*/ 
array[i]=ADS7804(); /*Sampling, storage*/ 
} 
TR0=0; /*Stop timing*/ 
}