/*****************************************************************************/
/*                                                                           */
/* PROJECT : SAMSUNG ECC for 256byte                                         */
/* FILE    : SAMSUNG_ECC.c                                                   */
/* PURPOSE : This file implements core ECC algorithms adopted     */
/*           Hamming Error Correction and Detection Algorithm                */
/*                                                                           */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/*        COPYRIGHT 2000-2004, SAMSUNG ELECTRONICS CO., LTD.                 */
/*                      ALL RIGHTS RESERVED                                  */
/*                                                                           */
/*   Permission is hereby granted to licensees of Samsung Electronics        */
/*   Co., Ltd. products to use or abstract this computer program for the     */
/*   sole purpose of implementing a product based on Samsung                 */
/*   Electronics Co., Ltd. products. No other rights to reproduce, use,      */
/*   or disseminate this computer program, whether in part or in whole,      */
/*   are granted.                                                            */
/*                                                                           */
/*   Samsung Electronics Co., Ltd. makes no representation or warranties     */
/*   with respect to the performance of this computer program, and           */
/*   specifically disclaims any responsibility for any damages,              */
/*   special or consequential, connected with the use of this program.       */
/*                                                                           */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/* REVISION HISTORY                                                          */
/*                                                                           */
/*  13-NOV-2003 [Chang JongBaek] :  first writing                            */
/*  03-MAR-2004 [ Kim YoungGon ] :  Second writing                           */
/*  03-MAR-2004 [  Lee JaeBum  ] :  Third writing                            */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/* NOTES                                                                     */
/*                                                                           */
/* - Make ECC parity code of 256bytes is represented                         */
/*   And ECC compare & Correction code is also represented                   */
/*                                                                           */
/*****************************************************************************/
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/timeb.h>
#include <string.h>

/*****************************************************************************/
/* Address Types                                                             */
/*****************************************************************************/

typedef unsigned char *  address_t;   /* address (pointer) */
typedef unsigned long  address_value_t; /* address (for calculation) */

typedef unsigned long  ULONG; /* address (for calculation) */

typedef unsigned int        uint;
typedef unsigned char       uchar;

/*****************************************************************************/
/* Integer Types                                                             */
/*****************************************************************************/

typedef unsigned int  uint32_t;   /* unsigned 4 byte integer */
typedef signed int   int32_t;   /* signed 4 byte integer */
typedef unsigned short  uint16_t;   /* unsigned 2 byte integer */
typedef signed short  int16_t;   /* signed 2 byte integer */
typedef unsigned char  uint8_t;   /* unsigned 1 byte integer */
typedef signed char   int8_t;    /* signed 1 byte integer */
typedef unsigned int  UINT32;   /* unsigned 4 byte integer */
typedef unsigned char  UINT8;   /* unsigned 1 byte integer */
typedef signed int   INT32;   /* signed 4 byte integer */

typedef unsigned int  UINT;   /* unsigned 4 byte integer */
typedef signed int      INT;   /* signed   4 byte integer */
typedef unsigned short  USHORT;   /* unsigned 2 byte integer */
typedef signed short  SHORT;   /* signed   2 byte integer */
typedef unsigned char  UCHAR;   /* unsigned 1 byte integer */
typedef signed char      CHAR;   /* signed   1 byte integer */

UCHAR ecc_gen[3];

typedef enum {
 ECC_NO_ERROR   = 0,  /* no error */
 ECC_CORRECTABLE_ERROR = 1,  /* one bit data error */
 ECC_ECC_ERROR   = 2,  /* one bit ECC error */
 ECC_UNCORRECTABLE_ERROR = 3   /* uncorrectable error */
} eccdiff_t;

void     make_ecc_256(unsigned char*, unsigned char*);
eccdiff_t compare_ecc(unsigned char*, unsigned char*, unsigned char*, int, unsigned char);

/*****************************************************************************/
/*                                                                           */
/* NAME                                                                      */
/*  make_ecc_256                                                         */
/* DESCRIPTION                                                               */
/*  This function generates 3 byte ECC for 512 byte data.                */
/*      (Software ECC)                                                       */
/* PARAMETERS                                                                */
/*  ecc_buf   the location where ECC should be stored              */
/*  data_buf  given data                                           */
/* RETURN VALUES                                                             */
/*  none                                                                 */
/*                                                                           */
/*****************************************************************************/
void make_ecc_256(unsigned char* ecc_buf, unsigned char* data_buf)
{
 
    unsigned int i;
 unsigned int tmp;
 unsigned int uiparity = 0;
 unsigned int parityCol, ecc = 0;
 unsigned int parityCol4321 = 0, parityCol4343 = 0, parityCol4242 = 0, parityColTot = 0;
 unsigned int* Data = (unsigned int*)(data_buf);
 unsigned int Xorbit=0;

 for( i = 0; i < 8; i++)
 {
  parityCol = *Data++;
  tmp = *Data++; parityCol ^= tmp; parityCol4242 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4343 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4343 ^= tmp; parityCol4242 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4321 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4242 ^= tmp; parityCol4321 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4343 ^= tmp; parityCol4321 ^= tmp;
  tmp = *Data++; parityCol ^= tmp; parityCol4242 ^= tmp; parityCol4343 ^= tmp; parityCol4321 ^= tmp;

  parityColTot ^= parityCol;

  tmp = (parityCol >> 16) ^ parityCol;
  tmp = (tmp >> 8) ^ tmp;
  tmp = (tmp >> 4) ^ tmp;
  tmp = ((tmp >> 2) ^ tmp) & 0x03;
  if ((tmp == 0x01) || (tmp == 0x02))
  {
   uiparity ^= i;
   Xorbit ^= 0x01;
  }
 }

 tmp = (parityCol4321 >> 16) ^ parityCol4321;
 tmp = (tmp << 8) ^ tmp;
 tmp = (tmp >> 4) ^ tmp;
 tmp = (tmp >> 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x200; // p128

 tmp = (parityCol4343 >> 16) ^ parityCol4343;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp << 4) ^ tmp;
 tmp = (tmp << 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x80; // p64

 tmp = (parityCol4242 >> 16) ^ parityCol4242;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp << 4) ^ tmp;
 tmp = (tmp >> 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x20; // p32

 tmp = parityColTot & 0xFFFF0000;
 tmp = tmp >> 16;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp >> 4) ^ tmp;
 tmp = (tmp << 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x08; // p16

 tmp = parityColTot & 0xFF00FF00;
 tmp = (tmp >> 16) ^ tmp;
 tmp = (tmp >> 8);
 tmp = (tmp >> 4) ^ tmp;
 tmp = (tmp >> 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x02; // p8

 tmp = parityColTot & 0xF0F0F0F0 ;
 tmp = (tmp << 16) ^ tmp;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp << 2) ^ tmp;
 ecc |= ((tmp << 1) ^ tmp) & 0x800000; // p4

 tmp = parityColTot & 0xCCCCCCCC ;
 tmp = (tmp << 16) ^ tmp;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp << 4) ^ tmp;
 tmp = (tmp >> 2);
 ecc |= ((tmp << 1) ^ tmp) & 0x200000; // p2

 tmp = parityColTot & 0xAAAAAAAA ;
 tmp = (tmp << 16) ^ tmp;
 tmp = (tmp >> 8) ^ tmp;
 tmp = (tmp >> 4) ^ tmp;
 tmp = (tmp << 2) ^ tmp;
 ecc |= (tmp & 0x80000); // p1

 ecc |= (uiparity & 0x01) <<11; // parit256_1
 ecc |= (uiparity & 0x02) <<12; // parit512_1
 ecc |= (uiparity & 0x04) <<13; // parit1024_1

 if (Xorbit)
 {
  ecc |= (ecc ^ 0x00A8AAAA)>>1;
 }
 else
 {
  ecc |= (ecc >> 1);
 }

 ecc = ~ecc;
 *(ecc_buf + 2) = (unsigned char) (ecc >> 16);
 *(ecc_buf + 1) = (unsigned char) (ecc >> 8);
 *(ecc_buf + 0) = (unsigned char) (ecc);
}

/*****************************************************************************/
/*                                                                           */
/* NAME                                                                      */
/*  compare_ecc_256                                                      */
/* DESCRIPTION                                                               */
/*  This function compares two ECCs and indicates if there is an error.  */
/* PARAMETERS                                                                */
/*  ecc_data1  one ECC to be compared                               */
/*  ecc_data2  the other ECC to be compared                         */
/*  page_data  content of data page                                 */
/*  offset   where the error occurred                             */
/*  corrected  correct data                                         */
/* RETURN VALUES                                                             */
/*  Upon successful completion, compare_ecc returns SSR_SUCCESS.         */
/*      Otherwise, corresponding error code is returned.                     */
/*                                                                           */
/*****************************************************************************/
eccdiff_t compare_ecc_256(uint8_t *iEccdata1, uint8_t *iEccdata2,
          uint8_t *pPagedata, int32_t pOffset, uint8_t pCorrected)
{

 uint32_t  iCompecc = 0, iEccsum = 0;
    uint32_t  iFindbyte   = 0;
    uint32_t  iIndex;
    uint32_t  nT1 = 0, nT2 =0;
 uint8_t   iNewvalue;
    uint8_t   iFindbit    = 0;

    uint8_t   *pEcc1 = (uint8_t *)iEccdata1;
    uint8_t   *pEcc2 = (uint8_t *)iEccdata2;

 for ( iIndex = 0; iIndex <2; iIndex++)
    {
        nT1 ^= (((*pEcc1) >> iIndex) & 0x01);
        nT2 ^= (((*pEcc2) >> iIndex) & 0x01);
    }

    for (iIndex = 0; iIndex < 3; iIndex++)
        iCompecc |= ((~(*pEcc1++) ^ ~(*pEcc2++)) << iIndex * 8);
   
    for(iIndex = 0; iIndex < 24; iIndex++) {
        iEccsum += ((iCompecc >> iIndex) & 0x01);
    }
   
    switch (iEccsum) {
    case 0 :
  printf("RESULT : no error\n");
        return ECC_NO_ERROR;

 case 1 :
  printf("RESULT : ECC 1 bit error\n");
  return ECC_ECC_ERROR;

    case 11 :
        if (nT1 != nT2)
        {
            iFindbyte = (  ((iCompecc >> 15 & 1) << 7) + ((iCompecc >> 13 & 1) << 6)
                      + ((iCompecc >> 11 & 1) << 5) + ((iCompecc >> 9 & 1) << 4) + ((iCompecc >> 7 & 1) << 3)
                      + ((iCompecc >> 5 & 1) << 2) + ((iCompecc >> 3 & 1) << 1) + (iCompecc >> 1 & 1) );
            iFindbit =  (uint8_t)(((iCompecc >> 23 & 1) << 2) + ((iCompecc >> 21 & 1) << 1) + (iCompecc >> 19 & 1));
            iNewvalue = (uint8_t)(pPagedata[iFindbyte] ^ (1 << iFindbit));
            printf("iCompecc = %d\n",iCompecc);
            printf("RESULT : one bit error\r\n");
            printf("byte = %d, bit = %d\r\n", iFindbyte, iFindbit);
            printf("corrupted = %x, corrected = %x\r\n", pPagedata[iFindbyte], iNewvalue);
            if (pOffset != NULL) {
                pOffset = iFindbyte;
            }
            if (pCorrected != NULL) {
                pCorrected = iNewvalue;
            }
           
            return ECC_CORRECTABLE_ERROR;
        }
        else
            return ECC_UNCORRECTABLE_ERROR;

    default :
  printf("RESULT : unrecoverable error\n");
        return ECC_UNCORRECTABLE_ERROR;
    }  
}