void ext2_disk_read_block(uint32_t block_no, uint8_t *buf) {
if (!block_no) return;
spin_lock(&lock);
int oldest = -1;
uint32_t oldest_age = UINT32_MAX;
for (uint32_t i = 0; i < CACHEENTRIES; ++i) {
if (DC[i].block_no == block_no) {
DC[i].last_use = ext2_time();
memcpy(buf, &DC[i].block, BLOCKSIZE);
spin_unlock(&lock);
return;
}
if (DC[i].last_use < oldest_age) {
oldest = i;
oldest_age = DC[i].last_use;
}
}
for (uint32_t i = 0; i < BLOCKSIZE / SECTORSIZE; ++i) {
ide_read_sector(DISK_PORT, 0, btos(block_no) + i, (uint8_t *)((uint32_t)&(DC[oldest].block) + SECTORSIZE * i));
}
if (DC[oldest].dirty) {
ext2_flush_dirty(oldest);
}
memcpy(buf, &DC[oldest].block, BLOCKSIZE);
DC[oldest].block_no = block_no;
DC[oldest].last_use = ext2_time();
DC[oldest].dirty = 0;
spin_unlock(&lock);
}
int read_partition_map(int device) {
ide_init(DISK_PORT);
ide_read_sector(DISK_PORT, 0, 0, (uint8_t *)&mbr);
if (mbr.signature[0] == 0x55 && mbr.signature[1] == 0xAA) {
debug_print(INFO, "Partition table found.");
for (int i = 0; i < 4; ++i) {
if (mbr.partitions[i].status & 0x80) {
debug_print(NOTICE, "Partition #%d: @%d+%d", i+1, mbr.partitions[i].lba_first_sector, mbr.partitions[i].sector_count);
} else {
debug_print(NOTICE, "Partition #%d: inactive", i+1);
}
}
return 0;
} else {
debug_print(ERROR, "Did not find partition table.");
debug_print(ERROR, "Signature was 0x%x 0x%x instead of 0x55 0xAA", mbr.signature[0], mbr.signature[1]);
debug_print(ERROR, "Parsing anyone yields:");
for (int i = 0; i < 4; ++i) {
if (mbr.partitions[i].status & 0x80) {
debug_print(NOTICE, "Partition #%d: @%d+%d", i+1, mbr.partitions[i].lba_first_sector, mbr.partitions[i].sector_count);
} else {
debug_print(NOTICE, "Partition #%d: inactive", i+1);
}
}
}
return 1;
}