Pic microcontroller control clock chip DS1302 program

#include <pic.h> // Includes internal resources of the microcontroller
__CONFIG(0x1832);
// Chip configuration word: watchdog off, power-on delay on, power-down detection off, low-voltage programming off, encryption, 4M crystal HS oscillation

#define i_o RB4 // Define data port for DS1302
#define sclk RB0 // Define clock port for DS1302
#define rst RB5 // Define reset port for DS1302

// unsigned char time_rx;
unsigned char time_rx @ 0x30; // Define receiving register
static volatile bit time_rx7 @(unsigned)&time_rx * 8 + 7; // Highest bit of receive register
// static volatile bit temp0 @(unsigned)&temp * 8 + 0;

void port_init(); // Declare pin initialization function
void ds1302_init(); // Declare DS1302 initialization function
void set_time(); // Declare set time function
void get_time(); // Declare read time function
void display(); // Declare display function
void time_write_1(unsigned char time_tx); // Declare byte write function
unsigned char time_read_1(); // Declare byte read function
void delay(); // Declare delay function

// Define the time to be set: seconds, minutes, hours, day, month, week, year, control bits
const char table[] = {0x00, 0x58, 0x12, 0x08, 0x03, 0x06, 0x06, 0x00};
// Define the storage table for reading time and date
char table1[7];
// Define display code for digits 0-9
const char table2[] = {0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90};

//---------------------------------------------
// Main function
void main()
{
port_init(); // Call pin initialization function
ds1302_init(); // Call DS1302 initialization function
set_time(); // Call set time function
while(1)
{
get_time(); // Call get time function
display(); // Call display function
}
}

//---------------------------------------------
// DS1302 initialization function
void ds1302_init()
{
sclk = 0; // Pull down clock signal
rst = 0; // Reset DS1302
rst = 1; // Enable DS1302
time_write_1(0x8e); // Send control command
time_write_1(0); // Allow writing to DS1302
rst = 0; // Reset
}

//---------------------------------------------
// Set time function
void set_time()
{
int i; // Define loop variable
rst = 1; // Enable DS1302
time_write_1(0xbe); // Clock multi-byte write command
for(i=0; i<8; i++) // Write 8 bytes of data continuously
{
time_write_1(table[i]); // Call write one byte function
}
rst = 0; // Reset
}

//---------------------------------------------
// Read time function
void get_time()
{
int i; // Define loop variable
rst = 1; // Enable DS1302
time_write_1(0xbf); // Send multi-byte read command
for(i=0; i<7; i++) // Read 7 bytes of data continuously
{
table1[i] = time_read_1(); // Call read one byte function
}
rst = 0; // Reset DS1302
}

//--------------------------------------------
// Write one byte function
void time_write_1(unsigned char time_tx)
{
int j; // Define loop variable
for(j=0; j<8; j++) // Write 8 bits continuously
{
i_o = 0; // Set data to 0
sclk = 0; // Pull down clock signal
if(time_tx & 0x01) // Determine if the data bit is 0 or 1
{
i_o = 1; // Data bit to send is 1
}
time_tx = time_tx >> 1; // Shift data to the right by 1 bit
sclk = 1; // Pull up clock signal
}
sclk = 0; // After writing a byte, pull down clock signal
}

//---------------------------------------------
// Read one byte function
unsigned char time_read_1()
{
int j; // Define loop variable
TRISB4 = 1; // Set data port direction to input
for(j=0; j<8; j++) // Read 8 bits continuously
{
sclk = 0; // Pull down clock signal
time_rx = time_rx >> 1; // Shift receive register right by 1 bit
time_rx7 = i_o; // Put received data into highest bit of receive register
sclk = 1; // Pull up clock signal
}
TRISB4 = 0; // Restore data port direction to output
sclk = 0; // Pull down clock signal
return(time_rx); // Return read data
}

//--------------------------------------------
// Pin definition function
void port_init()
{
TRISA = 0x00; // Set A port as full output
TRISD = 0x00; // Set D port as full output
ADCON1 = 0x06; // Set A port as normal I/O
TRISB = 0x02; // Set RB1 as input, others as output
OPTION = 0x00; // Enable weak pull-up on B port
PORTA = 0xFF;
PORTD = 0xFF; // Turn off all displays initially
}

//-------------------------------------------
// Display function
void display()
{
int i; // Define table lookup variable
if(RB1 == 0) // Check if RB1 is pressed; if so, display date instead of time
{
table1[0] = table1[3];
table1[1] = table1[4];
table1[2] = table1[6];
}
i = table1[0] & 0x0f; // Get seconds digit
PORTD = table2[i]; // Send to D port for display
PORTA = 0x1f; // Light up the second digit
delay(); // Delay for brightness
i = table1[0] & 0xf0; // Get tens of seconds
i = i >> 4; // Shift right by 4 bits
PORTD = table2[i]; // Send to D port for display
PORTA = 0x2f; // Light up the tens of seconds
delay(); // Delay for brightness

i = table1[1] & 0x0f; // Get minute digit
PORTD = table2[i] & 0x7f; // Send to D port with decimal point
PORTA = 0x37; // Light up the minute digit
delay(); // Delay for brightness
i = table1[1] & 0xf0; // Get tens of minutes
i = i >> 4; // Shift right by 4 bits
PORTD = table2[i]; // Send to D port for display
PORTA = 0x3b; // Light up the tens of minutes
delay(); // Delay for brightness

i = table1[2] & 0x0f; // Get hour digit
PORTD = table2[i] & 0x7f; // Send to D port with decimal point
PORTA = 0x3d; // Light up the hour digit
delay(); // Delay for brightness
i = table1[2] & 0xf0; // Get tens of hours
i = i >> 4; // Shift right by 4 bits
PORTD = table2[i]; // Send to D port for display
PORTA = 0x3e; // Light up the tens of hours
delay(); // Delay for brightness
}

//------------------------------------------------ ------------------
// Delay program
void delay() // Delay function
{
int i; // Define shaping variable
for(i = 0x64; i--;); // Delay loop
}

// Set initial time and date: seconds (00), minutes (58), hour (12), day (08), month (03), year (06)
// The six-digit digital display shows the time and date. By default, it shows time. The decimal point helps distinguish between minutes and hours.