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CD-ROM: Fix CRC and parity checking for XA Mode 2 Form 1 sectors.

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This commit is contained in:
OBattler
2025-07-24 16:49:01 +02:00
parent 91d2af521d
commit fb00027eff
3 changed files with 33 additions and 36 deletions
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19
src/cdrom/cdrom.c
View File

@@ -295,7 +295,7 @@ msf_to_bcd(int *m, int *s, int *f)
void
cdrom_compute_ecc_block(cdrom_t *dev, uint8_t *parity, const uint8_t *data,
uint32_t major_count, uint32_t minor_count,
uint32_t major_mult, uint32_t minor_inc)
uint32_t major_mult, uint32_t minor_inc, int m2f1)
{
uint32_t size = major_count * minor_count;
@@ -308,6 +308,9 @@ cdrom_compute_ecc_block(cdrom_t *dev, uint8_t *parity, const uint8_t *data,
for (uint32_t minor = 0; minor < minor_count; ++minor) {
uint8_t temp = data[index];
if (m2f1 && (index < 4))
temp = 0x00;
index += minor_inc;
if (index >= size)
@@ -323,14 +326,14 @@ cdrom_compute_ecc_block(cdrom_t *dev, uint8_t *parity, const uint8_t *data,
}
}
extern void
cdrom_generate_ecc_data(cdrom_t *dev, const uint8_t *data)
static void
cdrom_generate_ecc_data(cdrom_t *dev, const uint8_t *data, int m2f1)
{
/* Compute ECC P code. */
cdrom_compute_ecc_block(dev, dev->p_parity, data, 86, 24, 2, 86);
cdrom_compute_ecc_block(dev, dev->p_parity, data, 86, 24, 2, 86, m2f1);
/* Compute ECC Q code. */
cdrom_compute_ecc_block(dev, dev->q_parity, data, 52, 43, 86, 88);
cdrom_compute_ecc_block(dev, dev->q_parity, data, 52, 43, 86, 88, m2f1);
}
static int
@@ -338,8 +341,9 @@ cdrom_is_sector_good(cdrom_t *dev, const uint8_t *b, const uint8_t mode2, const
{
int ret = 1;
if (!mode2 || (form != 1)) {
if (mode2 && (form == 1)) {
const uint32_t crc = cdrom_crc32(0xffffffff, b, 2072) ^ 0xffffffff;
const uint32_t crc = cdrom_crc32(0xffffffff, &(b[16]), 2056) ^ 0xffffffff;
ret = ret && (crc == (*(uint32_t *) &(b[2072])));
} else if (!mode2) {
@@ -348,10 +352,11 @@ cdrom_is_sector_good(cdrom_t *dev, const uint8_t *b, const uint8_t mode2, const
ret = ret && (crc == (*(uint32_t *) &(b[2064])));
}
cdrom_generate_ecc_data(dev, &(b[12]));
cdrom_generate_ecc_data(dev, &(b[12]), mode2 && (form == 1));
ret = ret && !memcmp(dev->p_parity, &(b[2076]), 172);
ret = ret && !memcmp(dev->q_parity, &(b[2248]), 104);
}
return ret;
}

28
src/cdrom/cdrom_image.c
View File

@@ -19,7 +19,6 @@
#define __STDC_FORMAT_MACROS
#include <ctype.h>
#include <inttypes.h>
// #define ENABLE_IMAGE_LOG 1
#ifdef ENABLE_IMAGE_LOG
#include <stdarg.h>
#endif
@@ -2045,7 +2044,7 @@ image_load_mds(cd_image_t *img, const char *mdsfile)
ci->file = tf;
} else {
ci->start = (mds_trk_block.pm * 60 * 75) + (mds_trk_block.ps * 75) + mds_trk_block.pf;
ci->type = INDEX_ZERO;
ci->type = INDEX_NONE;
ci->file_start = 0;
ci->file_length = 0;
ci->file = NULL;
@@ -2309,28 +2308,21 @@ image_read_sector(const void *local, uint8_t *buffer,
if ((ret > 0) && (trk->attr & 0x04) && ((idx->type < INDEX_NORMAL) || !track_is_raw)) {
uint32_t crc;
if ((trk->mode == 2) && (trk->form == 1))
crc = cdrom_crc32(0xffffffff, buf, 2072) ^ 0xffffffff;
else
if ((trk->mode == 2) && (trk->form == 1)) {
crc = cdrom_crc32(0xffffffff, &(buf[16]), 2056) ^ 0xffffffff;
memcpy(&(buf[2072]), &crc, 4);
} else {
crc = cdrom_crc32(0xffffffff, buf, 2064) ^ 0xffffffff;
memcpy(&(buf[2064]), &crc, 4);
}
int m2f1 = (trk->mode == 2) && (trk->form == 1);
#if 0
/* Compute ECC P code. */
cdrom_compute_ecc_block(dev, dev->p_parity, &(buf[12]), 86, 24, 2, 86);
memcpy(&(buf[2076]), dev->p_parity, 172);
cdrom_compute_ecc_block(dev, &(buf[2076]), &(buf[12]), 86, 24, 2, 86, m2f1);
/* Compute ECC Q code. */
cdrom_compute_ecc_block(dev, dev->q_parity, &(buf[12]), 52, 43, 86, 88);
memcpy(&(buf[2248]), dev->q_parity, 104);
#else
/* Compute ECC P code. */
cdrom_compute_ecc_block(dev, &(buf[2076]), &(buf[12]), 86, 24, 2, 86);
/* Compute ECC Q code. */
cdrom_compute_ecc_block(dev, &(buf[2248]), &(buf[12]), 52, 43, 86, 88);
#endif
cdrom_compute_ecc_block(dev, &(buf[2248]), &(buf[12]), 52, 43, 86, 88, m2f1);
}
if ((ret > 0) && ((idx->type < INDEX_NORMAL) || (trk->subch_type != 0x08))) {

2
src/include/86box/cdrom.h
View File

@@ -459,7 +459,7 @@ extern void cdrom_reload(const uint8_t id);
extern void cdrom_compute_ecc_block(cdrom_t *dev, uint8_t *parity, const uint8_t *data,
uint32_t major_count, uint32_t minor_count,
uint32_t major_mult, uint32_t minor_inc);
uint32_t major_mult, uint32_t minor_inc, int m2f1);
extern unsigned long cdrom_crc32(unsigned long crc, const unsigned char *buf,
size_t len);