Skip to content

Commit

Permalink
increase huffman decoding speed by adding a cache of the huffman code…
Browse files Browse the repository at this point in the history 
…book
  • Loading branch information
@LangdaoZhang
LangdaoZhang committed Mar 20, 2024
1 parent 7835117 commit 6f53ef4
Showing 1 changed file with 129 additions and 173 deletions.
302 changes: 129 additions & 173 deletions include/SZ3/encoder/HuffmanEncoder.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -927,204 +927,160 @@ namespace SZ3{

size_t len=bytesToInt64_bigEndian(bytes)^0x1234abcd;
bytes+=8;
std::vector<T> a(targetLength);
size_t sza=0;
// a.reserve(targetLength);

// for(int i=0;i<len;){

// u=u->p[readBit(bytes,i++)];

// if(u->isLeaf()){

// a[sza++]=u->c+tree.offset;
// u=&tree.ht[tree.root];
// }
// }

// use unroll loops to optimize the above code
size_t byteIndex=0;
size_t i=0;
size_t b;

if(tree.n==0){

T c=0;
int j=0;

if(tree.offset==0){
for(;i+8<len;i+=8,byteIndex++){

b=bytes[byteIndex];

c|=((b)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>1)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>2)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>3)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>4)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>5)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>6)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
c|=((b>>7)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c,c=j=0;
std::vector<T> out(targetLength);
size_t outLen=0;

if (tree.limit > 16) {
//if huffman tree is large, a cache of huffman codebook is used to increase the performance
//Reference paper: Xiangyu Zou, Tao Lu, Wen Xia, Xuan Wang, Weizhe Zhang, Haijun Zhang, Sheng Di, Dingwen Tao, and Franck Cappello, "Performance Optimization for Relative-Error-Bounded Lossy Compression on Scientific Data", IEEE Transactions on Parallel and Distributed Systems (IEEE TPDS), 2020.
//Reference code: https://github.com/szcompressor/SZ/blob/a92658e785c072de1061f549c6cbc6d42d0f7f22/sz/src/Huffman.c#L345

int maxBits = 16;
size_t count = 0;
Node *t = &tree.ht[tree.root];
Node *n = t;

int tableSize = 1 << maxBits;
std::vector<int> valueTable(tableSize);
std::vector<uint8_t> lengthTable(tableSize);
std::vector<Node *> nodeTable(tableSize);
int j;
for (uint32_t i = 0; i < tableSize; i++) {
n = t;
j = 0;
uint32_t res = i;
while (!n->isLeaf() && j < maxBits) {
n = n->p[res & 0x00000001];
res >>= 1;
j++;
}
}
else{
for(;i+8<len;i+=8,byteIndex++){

b=bytes[byteIndex];

c|=((b)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>1)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>2)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>3)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>4)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>5)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>6)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
c|=((b>>7)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
if (!n->isLeaf()) {
nodeTable[i] = n;
valueTable[i] = -1;
lengthTable[i] = maxBits;
} else {
valueTable[i] = n->c + tree.offset;
lengthTable[i] = j;
}
}

b=bytes[byteIndex];

for(size_t k=0;k<len-i;k++){

c|=((b>>k)&1)<<j,++j;
if(j==tree.mbft) a[sza++]=c+tree.offset,c=j=0;
}

bytes+=(len+7)>>3;

return a;
}

if(tree.offset==0){
int leftBits = 0;
uint32_t currentValue = 0;
size_t i = 0;

for(;i+8<len;i+=8,byteIndex++){

b=bytes[byteIndex];

u=u->p[b&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>1)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>2)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>3)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
while (count < targetLength) {
while (leftBits < maxBits) {
currentValue += (bytes[i] << leftBits);
leftBits += 8;
i++;
}
u=u->p[(b>>4)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>5)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>6)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];
}
u=u->p[(b>>7)&1];
if(u->isLeaf()){
a[sza++]=u->c;
u=&tree.ht[tree.root];

uint32_t index = currentValue & ((1 << maxBits) - 1);
int value = valueTable[index];
if (value != -1) {
out[count] = value;
int bitLength = lengthTable[index];
leftBits -= bitLength;
currentValue >>= bitLength;
count++;
} else {
int bitLength = lengthTable[index];
leftBits -= bitLength;
currentValue >>= bitLength;
n = nodeTable[index];
while (!n->isLeaf()) {
if (!leftBits) {
currentValue += (bytes[i] << leftBits);
leftBits += 8;
i++;
}
n = n->p[(currentValue & 0x01)];
leftBits--;
currentValue >>= 1;
}
out[count] = n->c + tree.offset;
count++;
}
}
}
else{

for(;i+8<len;i+=8,byteIndex++){

b=bytes[byteIndex];

u=u->p[b&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
} else {

// for small huffman tree, use loop unrolling to increase the performance
// for(int i=0;i<len;){
// u=u->p[readBit(bytes,i++)];
// if(u->isLeaf()){
// out[outLen++]=u->c+tree.offset;
// u=&tree.ht[tree.root];
// }
// }

int byteIndex = 0;
int i = 0;
uchar b;
Node *u = &tree.ht[tree.root];
auto offset = tree.offset;

for (; i + 8 < len; i += 8, byteIndex++) {

b = bytes[byteIndex];

u = u->p[b & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>1)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 1) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>2)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 2) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>3)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 3) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>4)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 4) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>5)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 5) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>6)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 6) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
u=u->p[(b>>7)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> 7) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + offset;
u = &tree.ht[tree.root];
}
}
}

b=bytes[byteIndex];
b = bytes[byteIndex];

for(size_t j=0;j<len-i;j++){
for (int j = 0; j < len - i; j++) {

u=u->p[(b>>j)&1];
if(u->isLeaf()){
a[sza++]=u->c+tree.offset;
u=&tree.ht[tree.root];
u = u->p[(b >> j) & 1];
if (u->isLeaf()) {
out[outLen++] = u->c + tree.offset;
u = &tree.ht[tree.root];
}
}
}

bytes+=(len+7)>>3;
bytes += (len + 7) >> 3;

timer.stop("decode");

return a;
return out;
}

void postprocess_decode(){
Expand Down

0 comments on commit 6f53ef4

Please sign in to comment.