PIC16f877 simulate spi code!

[kerden]

spi_init pic 16f877

hi,
pic16f877 has an inner spi, but i want to simulate to communicate EEPROM 93LC46B(64 *16bit not the same as 93lc46A).my code as follow.but it don't out the data. what's the matter?
thank you.

//--------------------------------------
PIC chip and 93LC46B;
//==================================

#include"pic.h"

#define uchar unsigned char
#define uint unsigned int

#define CS RB1
#define SCK RB2
#define SDI RB4
#define SDO RB5

#define NOP() asm("nop")
#define SomeNOP(); NOP(); NOP(); NOP(); NOP();

void spi_init();
void spi_lck();
void spi_start_bit();
void spi_ewen();
void spi_ewds();
void spi_send_8bit(uchar send_data);
void  write93LC46(uchar write_add,uint write_data);
uint  read93LC46(uchar read_add);

void spi_lck()
{
	SCK = 1;
	SomeNOP();
	SCK = 0;	
}

void spi_start_bit()
{
	CS = 1;
	SDO = 1;//start with 1
	spi_lck();
}

void spi_ewen()
{
	uchar i = 8;
	uchar output = 0x30;//0011xxxxx
	
	spi_start_bit();
	while (i--)
	{
		SDO = (bit)(output & 0x80); 
		spi_lck();
		output <<= 1;	
	}
	CS = 0;	
}

void spi_ewds()
{
	uchar i = 8;
	
	spi_start_bit();
	SDO = 0;
	while(i--)
	{
		spi_lck();
	}
	CS = 0;	
}

void spi_send_8bit(uchar send_data)
{
	uchar i = 8;	
	while(i--)
	{
		SDO = (bit)(send_data & 0x80); 
		spi_lck();
		send_data <<= 1;
	}
}

void  write93LC46(uchar write_add,uint write_data)
{
	uchar comd_add = 0x40;
	uchar i = 16;
	
	spi_ewen();
	spi_start_bit();
		
	write_add &= 0x3f;////6 bit address，01XXXXXX and 2bit Opcode
	comd_add |= write_add;
	spi_send_8bit(comd_add);

	while(i--)
	{
		SDO = (bit)(write_data & 0x8000); 
                                //64 x 16 bit organization (93LC46B) should write two byte

		spi_lck();
		write_data <<= 1;
	}
	while(!RB4);//wait write complete
	CS = 0;
	
}

uint  read93LC46(uchar read_add)
{
	uchar comd_add = 0x80;
	uchar i = 16;
	uint read_data;
	
	spi_ewen();
	spi_start_bit();	
	
	read_add &= 0x3f;//6 bit address，10XXXXXX
	comd_add |= read_add;
	spi_send_8bit(comd_add);
	
	read_data = 0x0000;//64 x 16 bit organization (93LC46B) should  send two byte

	while(i--)
	{
		spi_lck();
		read_data |= (uint)SDI;
		if(i != 0)//the lass time don't run
		{
			read_data <<= 1;
		}	
	}
	CS = 0;
	return read_data;
}

void spi_init()
{
	TRISB = 0x10;//SDI "1"，SDO/SCK/CS "0"
	PORTB = 0;//CS = 0,SCK = 0;
	RBPU = 0;		
}


main()
{
	uint data;
	spi_init();
	write93LC46(0x05,0x5555);
	data = read93LC46(0x05);
	while(1);
}