// Program to generate a  column parity table for yaffs_ecc.c// Generate a column parity byte for a byte.// This byte is already aligned for the ecc.// The output byte has the form:// bit 7: p4// bit 6: p4'// bit 5: p2// bit 4: p2'// bit 3: p1// bit 2: p1'// bit 1: unused.// bit 0 of the output byte holds the line parity.unsigned char entry(unsigned char x){	unsigned char b0, b1, b2, b3, b4, b5, b6, b7;	unsigned char p4, p2, p1, p4p, p2p, p1p;	unsigned char linep;	unsigned char result;		b0 = (x & 0x01) ? 1 : 0;	b1 = (x & 0x02) ? 1 : 0;	b2 = (x & 0x04) ? 1 : 0;	b3 = (x & 0x08) ? 1 : 0;	b4 = (x & 0x10) ? 1 : 0;	b5 = (x & 0x20) ? 1 : 0;	b6 = (x & 0x40) ? 1 : 0;	b7 = (x & 0x80) ? 1 : 0;		p4 = b7 ^ b6 ^ b5 ^ b4;     p4p = b3 ^ b2 ^ b1 ^ b0;	p2 = b7 ^ b6 ^ b3 ^ b2;     p2p = b5 ^ b4 ^ b1 ^ b0;	p1 = b7 ^ b5 ^ b3 ^ b1;     p1p = b6 ^ b4 ^ b2 ^ b0;		linep = p1 ^ p1p;		result = 0;	if(p4)    result |= 0x80;	if(p4p)   result |= 0x40;	if(p2)    result |= 0x20;	if(p2p)   result |= 0x10;	if(p1)    result |= 0x08;	if(p1p)   result |= 0x04;	if(linep) result |= 0x01;		//result >>= 2;	//if(linep) result |= 0x40;		return result;	}int main(int argc, char *argv[]){	unsigned i;		printf("const unsigned char column_parity_table[] = {");	for(i = 0; i < 256; i++)	{		if((i & 0xf) == 0) printf("\n");		printf("0x%02x, ",entry((unsigned char) i));	}	printf("\n};\n");}