driver-api/mtd/nand_ecc.rst

45 byte   0:  bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0   rp0 rp2 rp4 ... rp14
46 byte   1:  bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0   rp1 rp2 rp4 ... rp14
47 byte   2:  bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0   rp0 rp3 rp4 ... rp14
48 byte   3:  bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0   rp1 rp3 rp4 ... rp14
49 byte   4:  bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0   rp0 rp2 rp5 ... rp14
98 - rp14 covers 128 bytes then skips 128
108 ECC 1   rp15  rp14  rp13  rp12  rp11  rp10  rp09  rp08
159       rp14 = bit7 ^ bit6 ^ bit5 ^ bit4 ^ bit3 ^ bit2 ^ bit1 ^ bit0 ^ rp14;
218       unsigned char rp8, rp9, rp10, rp11, rp12, rp13, rp14, rp15;
225       rp12 = 0; rp13 = 0; rp14 = 0; rp15 = 0;
238           if (i & 0x80) rp15 ^= cur; else rp14 ^= cur;
251           (parity[rp14] << 6) |
329       unsigned long rp8, rp9, rp10, rp11, rp12, rp13, rp14, rp15;
336       rp12 = 0; rp13 = 0; rp14 = 0; rp15 = 0;
347           if (i & 0x20) rp15 ^= cur; else rp14 ^= cur;
365       rp14 ^= (rp14 >> 16); rp14 ^= (rp14 >> 8); rp14 &= 0xff;
385           (parity[rp14] << 6) |
416 If we look at e.g. rp14 and rp15 we see that we either xor our data with
417 rp14 or with rp15. However we also have par which goes over all data.
418 This means there is no need to calculate rp14 as it can be calculated from
419 rp15 through rp14 = par ^ rp15, because par = rp14 ^ rp15;
421 rp14).  That is why some places refer to inverse parity.
438           if (i & 0x20) rp15 ^= cur; else rp14 ^= cur;
456           rp14  = par ^ rp15;
491         if (i & 0x2) rp15 ^= cur; else rp14 ^= cur;
519 The same holds for rp6/7, rp8/9, rp10/11 rp12/13 and rp14/15.
576         if ((i & 0x2) == 0) rp14 ^= tmppar;
581 to rp12 and rp14.
651         if ((i & 0x2) == 0) rp14 ^= tmppar;