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////////////////////////////////////////////////////////////////////////////////
//
#define TITLE "ecm - Encoder/decoder for Error Code Modeler format"
#define COPYR "Copyright (C) 2002-2011 Neill Corlett"
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////////////
//#include "common.h"
//#include "banner.h"
////////////////////////////////////////////////////////////////////////////////
//
// Sector types
//
// Mode 1
// -----------------------------------------------------
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
// 0000h 00 FF FF FF FF FF FF FF FF FF FF 00 [-ADDR-] 01
// 0010h [---DATA...
// ...
// 0800h ...DATA---]
// 0810h [---EDC---] 00 00 00 00 00 00 00 00 [---ECC...
// ...
// 0920h ...ECC---]
// -----------------------------------------------------
//
// Mode 2 (XA), form 1
// -----------------------------------------------------
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
// 0000h 00 FF FF FF FF FF FF FF FF FF FF 00 [-ADDR-] 02
// 0010h [--FLAGS--] [--FLAGS--] [---DATA...
// ...
// 0810h ...DATA---] [---EDC---] [---ECC...
// ...
// 0920h ...ECC---]
// -----------------------------------------------------
//
// Mode 2 (XA), form 2
// -----------------------------------------------------
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
// 0000h 00 FF FF FF FF FF FF FF FF FF FF 00 [-ADDR-] 02
// 0010h [--FLAGS--] [--FLAGS--] [---DATA...
// ...
// 0920h ...DATA---] [---EDC---]
// -----------------------------------------------------
//
// ADDR: Sector address, encoded as minutes:seconds:frames in BCD
// FLAGS: Used in Mode 2 (XA) sectors describing the type of sector; repeated
// twice for redundancy
// DATA: Area of the sector which contains the actual data itself
// EDC: Error Detection Code
// ECC: Error Correction Code
//
#define MAX(x, y) (((x) > (y)) ? (x) : (y))
#define ECM_HEADER_SIZE 4
u32 len_decoded_ecm_buffer=0; // same as decoded ECM file length or 2x size
u32 len_ecm_savetable=0; // same as sector count of decoded ECM file or 2x count
#ifdef ENABLE_ECM_FULL //setting this makes whole ECM to be decoded in-memory meaning buffer could eat up to 700 MB of memory
u32 decoded_ecm_sectors=1; // initially sector 1 is always decoded
#else
u32 decoded_ecm_sectors=0; // disabled
#endif
boolean ecm_file_detected = FALSE;
u32 prevsector;
FILE* decoded_ecm = NULL;
void *decoded_ecm_buffer;
// Function that is used to read CD normally
int (*cdimg_read_func_o)(FILE *f, unsigned int base, void *dest, int sector) = NULL;
typedef struct ECMFILELUT {
s32 sector;
s32 filepos;
} ECMFILELUT;
ECMFILELUT* ecm_savetable = NULL;
static const size_t ECM_SECTOR_SIZE[4] = {
1,
2352,
2336,
2336
};
////////////////////////////////////////////////////////////////////////////////
static uint32_t get32lsb(const uint8_t* src) {
return
(((uint32_t)(src[0])) << 0) |
(((uint32_t)(src[1])) << 8) |
(((uint32_t)(src[2])) << 16) |
(((uint32_t)(src[3])) << 24);
}
static void put32lsb(uint8_t* dest, uint32_t value) {
dest[0] = (uint8_t)(value );
dest[1] = (uint8_t)(value >> 8);
dest[2] = (uint8_t)(value >> 16);
dest[3] = (uint8_t)(value >> 24);
}
////////////////////////////////////////////////////////////////////////////////
//
// LUTs used for computing ECC/EDC
//
static uint8_t ecc_f_lut[256];
static uint8_t ecc_b_lut[256];
static uint32_t edc_lut [256];
static void eccedc_init(void) {
size_t i;
for(i = 0; i < 256; i++) {
uint32_t edc = i;
size_t j = (i << 1) ^ (i & 0x80 ? 0x11D : 0);
ecc_f_lut[i] = j;
ecc_b_lut[i ^ j] = i;
for(j = 0; j < 8; j++) {
edc = (edc >> 1) ^ (edc & 1 ? 0xD8018001 : 0);
}
edc_lut[i] = edc;
}
}
////////////////////////////////////////////////////////////////////////////////
//
// Compute EDC for a block
//
static uint32_t edc_compute(
uint32_t edc,
const uint8_t* src,
size_t size
) {
for(; size; size--) {
edc = (edc >> 8) ^ edc_lut[(edc ^ (*src++)) & 0xFF];
}
return edc;
}
//
// Write ECC block (either P or Q)
//
static void ecc_writepq(
const uint8_t* address,
const uint8_t* data,
size_t major_count,
size_t minor_count,
size_t major_mult,
size_t minor_inc,
uint8_t* ecc
) {
size_t size = major_count * minor_count;
size_t major;
for(major = 0; major < major_count; major++) {
size_t index = (major >> 1) * major_mult + (major & 1);
uint8_t ecc_a = 0;
uint8_t ecc_b = 0;
size_t minor;
for(minor = 0; minor < minor_count; minor++) {
uint8_t temp;
if(index < 4) {
temp = address[index];
} else {
temp = data[index - 4];
}
index += minor_inc;
if(index >= size) { index -= size; }
ecc_a ^= temp;
ecc_b ^= temp;
ecc_a = ecc_f_lut[ecc_a];
}
ecc_a = ecc_b_lut[ecc_f_lut[ecc_a] ^ ecc_b];
ecc[major ] = (ecc_a );
ecc[major + major_count] = (ecc_a ^ ecc_b);
}
}
//
// Write ECC P and Q codes for a sector
//
static void ecc_writesector(
const uint8_t *address,
const uint8_t *data,
uint8_t *ecc
) {
ecc_writepq(address, data, 86, 24, 2, 86, ecc); // P
ecc_writepq(address, data, 52, 43, 86, 88, ecc + 0xAC); // Q
}
////////////////////////////////////////////////////////////////////////////////
static const uint8_t zeroaddress[4] = {0, 0, 0, 0};
////////////////////////////////////////////////////////////////////////////////
//
// Reconstruct a sector based on type
//
static void reconstruct_sector(
uint8_t* sector, // must point to a full 2352-byte sector
int8_t type
) {
//
// Sync
//
sector[0x000] = 0x00;
sector[0x001] = 0xFF;
sector[0x002] = 0xFF;
sector[0x003] = 0xFF;
sector[0x004] = 0xFF;
sector[0x005] = 0xFF;
sector[0x006] = 0xFF;
sector[0x007] = 0xFF;
sector[0x008] = 0xFF;
sector[0x009] = 0xFF;
sector[0x00A] = 0xFF;
sector[0x00B] = 0x00;
switch(type) {
case 1:
//
// Mode
//
sector[0x00F] = 0x01;
//
// Reserved
//
sector[0x814] = 0x00;
sector[0x815] = 0x00;
sector[0x816] = 0x00;
sector[0x817] = 0x00;
sector[0x818] = 0x00;
sector[0x819] = 0x00;
sector[0x81A] = 0x00;
sector[0x81B] = 0x00;
break;
case 2:
case 3:
//
// Mode
//
sector[0x00F] = 0x02;
//
// Flags
//
sector[0x010] = sector[0x014];
sector[0x011] = sector[0x015];
sector[0x012] = sector[0x016];
sector[0x013] = sector[0x017];
break;
}
//
// Compute EDC
//
switch(type) {
case 1: put32lsb(sector+0x810, edc_compute(0, sector , 0x810)); break;
case 2: put32lsb(sector+0x818, edc_compute(0, sector+0x10, 0x808)); break;
case 3: put32lsb(sector+0x92C, edc_compute(0, sector+0x10, 0x91C)); break;
}
//
// Compute ECC
//
switch(type) {
case 1: ecc_writesector(sector+0xC , sector+0x10, sector+0x81C); break;
case 2: ecc_writesector(zeroaddress, sector+0x10, sector+0x81C); break;
}
//
// Done
//
}
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