calculation of 32 bit CRC(Cyclic Redundancy Code)in C

[khatavkar]

please help me!!
i have written a program to calculate 32 bit CRC(used for ETHERNET)..but its not working and giving correct output..
please let me know my mistakes..

output should be :E7 B0 51 93

/**************  program starts here *************************/
typedef unsigned long ul;
typedef unsigned char uchar;

uchar buffer_bytes[64] = {0x00,0x14,0x85,0x31,0x24,0x10,0x00,0x15,0x00,0x15,0x9f,0x07,0x08,0x06,0x00,0x01,0x08,0x00,0x06,0x04,0x00,0x02,0x00,0x15,0x00,0x15,0x9f,0x07,0xc0,0xa8,0x00,0x02,0x00,0x14,0x85,0x31,0x24,0x10,0xc0,0xa8,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
ul 	remainder ,temp;		//to get 32 bit number
unsigned short weld,joint;

unsigned char i,count = 0 ,str_length =64,  *ptr,j;


#define MSB 0x80000000;
#define POLY 0x04C11DB7	
#define printf printf_fast_f

void init_uart(void)
{
	ES = 0 ;                    //Disable serial interrupt.
	SCON = 0x50 ;				//mode 0,REN enabled
	BDRCON = 0x0E ;				//
	
	PCON &= 0x7F ;
	BRL = 224 ;
	BDRCON |= 0x10 ;	
}

void putchar(uchar send_this)
{
	uart_send_char(send_this);
}

void main(void)
{
	init_uart();

	ptr = &buffer_bytes[0];
	
	//----------------------------------------------------------------------------------------------------------/
	//			get 32 bit number out of the whole string 														/
	//----------------------------------------------------------------------------------------------------------/
	weld = (unsigned short)*ptr;																							   	
	ptr++;																									  						
	weld = ((weld << 8) & 0xff00) +  (unsigned short)*ptr;		//16 bit number higher											
	ptr++;
	joint =  (unsigned short)*ptr;
	ptr ++;
	
	joint = ((joint << 8) &0xff00) + (unsigned short) *ptr	;	//16 bit number lower
	ptr ++;														//pointer points the next byte after 4th byte
	remainder =  weld;
	remainder = (remainder << 16) & 0xffff0000  ;		
	remainder = remainder + joint;									//32 bit number
	
	
	//remainder = remainder ^ (ul) 0xFFFFFFFF;
//----------------------------------------------------------------------------------------------------

	//str_length = str_length  - 4;

	for(j = str_length; j>0 ; j--)					//str_length = no. of bytes in string
	{
		if((remainder & (ul)0xFF000000)==0x00000000)
		{
			remainder = remainder << 8;
			remainder = (remainder & (ul)0xFFFFFF00) | (ul)*ptr;
		}
		else
		{
			for(i=0; i<8 ; i++)
			{
			printf(" %lx\r\n",remainder);
				if((remainder & (ul)0x80000000) == (ul)0x80000000)		//if MSB is high then shift left by 1, get next bit 0
				{														
					remainder = remainder << 1;
					
					if((*ptr & 0x80) == 0x80)
					{
						remainder |= (ul)0x00000001;
					}
					else 
					{
						remainder |= (ul)0x00000000;
					}
					*ptr = *ptr << 1;							//XOR remainder with POLY
					printf("msg %lx\r\n",remainder);
					
					remainder = remainder ^ (ul)0x04C11DB7;
					printf("XOR abov msg wiD POLY\r\n");
				}
				else
				{
				
				//	while((remainder & (ul)0x80000000) == (ul)0x00000000)
				//	{
						remainder = remainder << 1;
						if((*ptr & 0x80) == 0x80)
						{
							remainder |= (ul)0x00000001;
						}
						else
						{ 
							remainder |= (ul)0x00000000;
						}
						*ptr = *ptr << 1;
				//		i++;
				//		if (i >= 8)break;
					//}
					
				}
			}
			ptr ++;
			//printf("ptr = %2x\r\n",*ptr);
		}
	}