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delta.hpp
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delta.hpp
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#ifndef NALL_BEAT_DELTA_HPP
#define NALL_BEAT_DELTA_HPP
#include <nall/crc32.hpp>
#include <nall/file.hpp>
#include <nall/filemap.hpp>
#include <nall/stdint.hpp>
#include <nall/string.hpp>
namespace nall {
struct bpsdelta {
inline void source(const uint8_t* data, unsigned size);
inline void target(const uint8_t* data, unsigned size);
inline bool source(const string& filename);
inline bool target(const string& filename);
inline bool create(const string& filename, const string& metadata = "");
protected:
enum : unsigned { SourceRead, TargetRead, SourceCopy, TargetCopy };
enum : unsigned { Granularity = 1 };
struct Node {
unsigned offset = 0;
Node* next = nullptr;
Node() = default;
~Node() { if(next) delete next; }
};
filemap sourceFile;
const uint8_t* sourceData;
unsigned sourceSize;
filemap targetFile;
const uint8_t* targetData;
unsigned targetSize;
};
void bpsdelta::source(const uint8_t* data, unsigned size) {
sourceData = data;
sourceSize = size;
}
void bpsdelta::target(const uint8_t* data, unsigned size) {
targetData = data;
targetSize = size;
}
bool bpsdelta::source(const string& filename) {
if(sourceFile.open(filename, filemap::mode::read) == false) return false;
source(sourceFile.data(), sourceFile.size());
return true;
}
bool bpsdelta::target(const string& filename) {
if(targetFile.open(filename, filemap::mode::read) == false) return false;
target(targetFile.data(), targetFile.size());
return true;
}
bool bpsdelta::create(const string& filename, const string& metadata) {
file modifyFile;
if(modifyFile.open(filename, file::mode::write) == false) return false;
uint32_t sourceChecksum = ~0, modifyChecksum = ~0;
unsigned sourceRelativeOffset = 0, targetRelativeOffset = 0, outputOffset = 0;
auto write = [&](uint8_t data) {
modifyFile.write(data);
modifyChecksum = crc32_adjust(modifyChecksum, data);
};
auto encode = [&](uint64_t data) {
while(true) {
uint64_t x = data & 0x7f;
data >>= 7;
if(data == 0) {
write(0x80 | x);
break;
}
write(x);
data--;
}
};
write('B');
write('P');
write('S');
write('1');
encode(sourceSize);
encode(targetSize);
unsigned markupSize = metadata.length();
encode(markupSize);
for(unsigned n = 0; n < markupSize; n++) write(metadata[n]);
Node* sourceTree[65536];
Node* targetTree[65536];
for(unsigned n = 0; n < 65536; n++) sourceTree[n] = nullptr, targetTree[n] = nullptr;
//source tree creation
for(unsigned offset = 0; offset < sourceSize; offset++) {
uint16_t symbol = sourceData[offset + 0];
sourceChecksum = crc32_adjust(sourceChecksum, symbol);
if(offset < sourceSize - 1) symbol |= sourceData[offset + 1] << 8;
Node *node = new Node;
node->offset = offset;
node->next = sourceTree[symbol];
sourceTree[symbol] = node;
}
unsigned targetReadLength = 0;
auto targetReadFlush = [&]() {
if(targetReadLength) {
encode(TargetRead | ((targetReadLength - 1) << 2));
unsigned offset = outputOffset - targetReadLength;
while(targetReadLength) write(targetData[offset++]), targetReadLength--;
}
};
while(outputOffset < targetSize) {
unsigned maxLength = 0, maxOffset = 0, mode = TargetRead;
uint16_t symbol = targetData[outputOffset + 0];
if(outputOffset < targetSize - 1) symbol |= targetData[outputOffset + 1] << 8;
{ //source read
unsigned length = 0, offset = outputOffset;
while(offset < sourceSize && offset < targetSize && sourceData[offset] == targetData[offset]) {
length++;
offset++;
}
if(length > maxLength) maxLength = length, mode = SourceRead;
}
{ //source copy
Node* node = sourceTree[symbol];
while(node) {
unsigned length = 0, x = node->offset, y = outputOffset;
while(x < sourceSize && y < targetSize && sourceData[x++] == targetData[y++]) length++;
if(length > maxLength) maxLength = length, maxOffset = node->offset, mode = SourceCopy;
node = node->next;
}
}
{ //target copy
Node* node = targetTree[symbol];
while(node) {
unsigned length = 0, x = node->offset, y = outputOffset;
while(y < targetSize && targetData[x++] == targetData[y++]) length++;
if(length > maxLength) maxLength = length, maxOffset = node->offset, mode = TargetCopy;
node = node->next;
}
//target tree append
node = new Node;
node->offset = outputOffset;
node->next = targetTree[symbol];
targetTree[symbol] = node;
}
{ //target read
if(maxLength < 4) {
maxLength = min((unsigned)Granularity, targetSize - outputOffset);
mode = TargetRead;
}
}
if(mode != TargetRead) targetReadFlush();
switch(mode) {
case SourceRead:
encode(SourceRead | ((maxLength - 1) << 2));
break;
case TargetRead:
//delay write to group sequential TargetRead commands into one
targetReadLength += maxLength;
break;
case SourceCopy:
case TargetCopy:
encode(mode | ((maxLength - 1) << 2));
signed relativeOffset;
if(mode == SourceCopy) {
relativeOffset = maxOffset - sourceRelativeOffset;
sourceRelativeOffset = maxOffset + maxLength;
} else {
relativeOffset = maxOffset - targetRelativeOffset;
targetRelativeOffset = maxOffset + maxLength;
}
encode((relativeOffset < 0) | (abs(relativeOffset) << 1));
break;
}
outputOffset += maxLength;
}
targetReadFlush();
sourceChecksum = ~sourceChecksum;
for(unsigned n = 0; n < 32; n += 8) write(sourceChecksum >> n);
uint32_t targetChecksum = crc32_calculate(targetData, targetSize);
for(unsigned n = 0; n < 32; n += 8) write(targetChecksum >> n);
uint32_t outputChecksum = ~modifyChecksum;
for(unsigned n = 0; n < 32; n += 8) write(outputChecksum >> n);
modifyFile.close();
return true;
}
}
#endif