Files
aurora/lib/card/BlockAllocationTable.cpp
CraftyBoss 18cdf141cb Implement CARD API based on kabufuda (#53)
Original repository: https://github.com/AxioDL/kabufuda
Cleaned up & converted to `aurora::card`, with SDL3 file I/O.

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Co-authored-by: Phillip Stephens <antidote.crk@gmail.com>
Co-authored-by: Jack Andersen <jackoalan@gmail.com>
Co-authored-by: Lioncash <mathew1800@gmail.com>
Co-authored-by: Luke Street <luke@street.dev>
2026-03-10 19:49:34 -06:00

107 lines
3.0 KiB
C++

#include "BlockAllocationTable.hpp"
#include <algorithm>
#include <vector>
#include "../internal.hpp"
#include "Util.hpp"
namespace aurora::card {
void BlockAllocationTable::swapEndian() {
m_checksum = bswap(m_checksum);
m_checksumInv = bswap(m_checksumInv);
m_updateCounter = bswap(m_updateCounter);
m_freeBlocks = bswap(m_freeBlocks);
m_lastAllocated = bswap(m_lastAllocated);
std::for_each(std::begin(m_map), std::end(m_map), [](uint16_t& val) { val = bswap(val); });
}
void BlockAllocationTable::updateChecksum() {
swapEndian();
calculateChecksumBE(reinterpret_cast<uint16_t*>(raw.data() + 4), 0xFFE, &m_checksum, &m_checksumInv);
swapEndian();
}
bool BlockAllocationTable::valid() const {
uint16_t ckSum = 0;
uint16_t ckSumInv = 0;
const_cast<BlockAllocationTable&>(*this).swapEndian();
calculateChecksumBE(reinterpret_cast<const uint16_t*>(raw.data() + 4), 0xFFE, &ckSum, &ckSumInv);
bool res = ckSum == m_checksum && ckSumInv == m_checksumInv;
const_cast<BlockAllocationTable&>(*this).swapEndian();
return res;
}
BlockAllocationTable::BlockAllocationTable(uint32_t blockCount)
: m_checksum{0}
, m_checksumInv{0}
, m_updateCounter{0}
, m_freeBlocks{static_cast<uint16_t>(blockCount - FSTBlocks)}
, m_lastAllocated{4}
, m_map{{}} {
updateChecksum();
}
uint16_t BlockAllocationTable::getNextBlock(uint16_t block) const {
if ((block < FSTBlocks) || (block > (BATSize - FSTBlocks)))
return 0xFFFF;
return m_map[block - FSTBlocks];
}
uint16_t BlockAllocationTable::nextFreeBlock(uint16_t maxBlock, uint16_t startingBlock) const {
if (m_freeBlocks > 0) {
maxBlock = std::min(maxBlock, static_cast<uint16_t>(BATSize));
for (uint16_t i = startingBlock; i < maxBlock; ++i)
if (m_map[i - FSTBlocks] == 0)
return i;
for (uint16_t i = FSTBlocks; i < startingBlock; ++i)
if (m_map[i - FSTBlocks] == 0)
return i;
}
return 0xFFFF;
}
bool BlockAllocationTable::clear(uint16_t first, uint16_t count) {
std::vector<uint16_t> blocks;
while (first != 0xFFFF && first != 0) {
blocks.push_back(first);
first = getNextBlock(first);
}
if (first > 0) {
size_t length = blocks.size();
if (length != count)
return false;
for (size_t i = 0; i < length; ++i)
m_map[blocks.at(i) - FSTBlocks] = 0;
m_freeBlocks += count;
return true;
}
return false;
}
uint16_t BlockAllocationTable::allocateBlocks(uint16_t count, uint16_t maxBlocks) {
uint16_t firstBlock = nextFreeBlock(maxBlocks - FSTBlocks, m_lastAllocated + 1);
uint16_t freeBlock = firstBlock;
if (freeBlock != 0xFFFF) {
uint16_t tmpCount = count;
while ((count--) > 0 && freeBlock != 0xFFFF) {
m_map[(freeBlock - FSTBlocks)] = 0xFFFF;
if (count != 0) {
m_map[(freeBlock - FSTBlocks)] = nextFreeBlock(maxBlocks - FSTBlocks, freeBlock + 1);
freeBlock = m_map[(freeBlock - FSTBlocks)];
}
}
if (freeBlock == 0xFFFF)
return 0xFFFF;
m_lastAllocated = freeBlock;
m_freeBlocks -= tmpCount;
}
return firstBlock;
}
} // namespace aurora::card