CDImage/ECM: Use EDC/ECC functions from libchdr
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Stenzek
parent
fe8dada392
commit
ac139d96f1
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@ -10,157 +10,13 @@
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#include "common/log.h"
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#include "common/path.h"
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#include "libchdr/cdrom.h"
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#include <array>
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#include <map>
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Log_SetChannel(CDImageEcm);
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// unecm.c by Neill Corlett (c) 2002, GPL licensed
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/* LUTs used for computing ECC/EDC */
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static constexpr std::array<u8, 256> ComputeECCFLUT()
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{
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std::array<u8, 256> ecc_lut{};
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for (u32 i = 0; i < 256; i++)
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{
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u32 j = (i << 1) ^ (i & 0x80 ? 0x11D : 0);
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ecc_lut[i] = static_cast<u8>(j);
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}
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return ecc_lut;
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}
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static constexpr std::array<u8, 256> ComputeECCBLUT()
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{
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std::array<u8, 256> ecc_lut{};
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for (u32 i = 0; i < 256; i++)
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{
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u32 j = (i << 1) ^ (i & 0x80 ? 0x11D : 0);
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ecc_lut[i ^ j] = static_cast<u8>(i);
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}
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return ecc_lut;
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}
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static constexpr std::array<u32, 256> ComputeEDCLUT()
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{
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std::array<u32, 256> edc_lut{};
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for (u32 i = 0; i < 256; i++)
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{
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u32 edc = i;
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for (u32 k = 0; k < 8; k++)
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edc = (edc >> 1) ^ (edc & 1 ? 0xD8018001 : 0);
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edc_lut[i] = edc;
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}
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return edc_lut;
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}
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static constexpr std::array<u8, 256> ecc_f_lut = ComputeECCFLUT();
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static constexpr std::array<u8, 256> ecc_b_lut = ComputeECCBLUT();
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static constexpr std::array<u32, 256> edc_lut = ComputeEDCLUT();
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/***************************************************************************/
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/*
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** Compute EDC for a block
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*/
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static u32 edc_partial_computeblock(u32 edc, const u8* src, u16 size)
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{
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while (size--)
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edc = (edc >> 8) ^ edc_lut[(edc ^ (*src++)) & 0xFF];
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return edc;
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}
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static void edc_computeblock(const u8* src, u16 size, u8* dest)
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{
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u32 edc = edc_partial_computeblock(0, src, size);
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dest[0] = (edc >> 0) & 0xFF;
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dest[1] = (edc >> 8) & 0xFF;
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dest[2] = (edc >> 16) & 0xFF;
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dest[3] = (edc >> 24) & 0xFF;
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}
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/***************************************************************************/
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/*
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** Compute ECC for a block (can do either P or Q)
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*/
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static void ecc_computeblock(u8* src, u32 major_count, u32 minor_count, u32 major_mult, u32 minor_inc, u8* dest)
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{
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u32 size = major_count * minor_count;
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u32 major, minor;
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for (major = 0; major < major_count; major++)
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{
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u32 index = (major >> 1) * major_mult + (major & 1);
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u8 ecc_a = 0;
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u8 ecc_b = 0;
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for (minor = 0; minor < minor_count; minor++)
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{
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u8 temp = src[index];
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index += minor_inc;
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if (index >= size)
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index -= size;
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ecc_a ^= temp;
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ecc_b ^= temp;
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ecc_a = ecc_f_lut[ecc_a];
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}
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ecc_a = ecc_b_lut[ecc_f_lut[ecc_a] ^ ecc_b];
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dest[major] = ecc_a;
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dest[major + major_count] = ecc_a ^ ecc_b;
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}
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}
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/*
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** Generate ECC P and Q codes for a block
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*/
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static void ecc_generate(u8* sector, int zeroaddress)
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{
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u8 address[4], i;
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/* Save the address and zero it out */
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if (zeroaddress)
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for (i = 0; i < 4; i++)
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{
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address[i] = sector[12 + i];
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sector[12 + i] = 0;
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}
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/* Compute ECC P code */
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ecc_computeblock(sector + 0xC, 86, 24, 2, 86, sector + 0x81C);
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/* Compute ECC Q code */
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ecc_computeblock(sector + 0xC, 52, 43, 86, 88, sector + 0x8C8);
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/* Restore the address */
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if (zeroaddress)
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for (i = 0; i < 4; i++)
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sector[12 + i] = address[i];
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}
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/***************************************************************************/
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/*
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** Generate ECC/EDC information for a sector (must be 2352 = 0x930 bytes)
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** Returns 0 on success
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*/
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static void eccedc_generate(u8* sector, int type)
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{
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switch (type)
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{
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case 1: /* Mode 1 */
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/* Compute EDC */
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edc_computeblock(sector + 0x00, 0x810, sector + 0x810);
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/* Write out zero bytes */
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for (u32 i = 0; i < 8; i++)
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sector[0x814 + i] = 0;
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/* Generate ECC P/Q codes */
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ecc_generate(sector, 0);
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break;
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case 2: /* Mode 2 form 1 */
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/* Compute EDC */
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edc_computeblock(sector + 0x10, 0x808, sector + 0x818);
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/* Generate ECC P/Q codes */
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ecc_generate(sector, 1);
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break;
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case 3: /* Mode 2 form 2 */
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/* Compute EDC */
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edc_computeblock(sector + 0x10, 0x91C, sector + 0x92C);
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break;
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}
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}
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namespace {
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class CDImageEcm : public CDImage
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@ -459,7 +315,8 @@ bool CDImageEcm::ReadChunks(u32 disc_offset, u32 size)
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if (std::fread(sector + 0x00C, 0x003, 1, m_fp) != 1 || std::fread(sector + 0x010, 0x800, 1, m_fp) != 1)
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return false;
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eccedc_generate(sector, 1);
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edc_set(§or[2064], edc_compute(sector, 2064));
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ecc_generate(sector);
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skip = 0;
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}
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break;
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@ -475,7 +332,8 @@ bool CDImageEcm::ReadChunks(u32 disc_offset, u32 size)
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sector[0x12] = sector[0x16];
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sector[0x13] = sector[0x17];
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eccedc_generate(sector, 2);
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edc_set(§or[2072], edc_compute(§or[16], 2056));
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ecc_generate(sector);
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skip = 0x10;
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}
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break;
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@ -491,7 +349,7 @@ bool CDImageEcm::ReadChunks(u32 disc_offset, u32 size)
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sector[0x12] = sector[0x16];
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sector[0x13] = sector[0x17];
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eccedc_generate(sector, 3);
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edc_set(§or[2348], edc_compute(§or[16], 2332));
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skip = 0x10;
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}
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break;
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