long BackendSelect1(int rank, BitStreamCtxRL ctx)
{
if (rank < 1) {
return -1;
}
// reset run_len
ctx.run_len = 0;
int start_index = (rank - 1) / this.B;
long acc;
int left;
//Console.WriteLine ("**** BaseSelect1> rank: {0}, start_index: {1}", rank, start_index);
if (start_index == 0) {
//if (this.Offsets.Count > 0 && this.Offsets [0] == 1) {
if (this.Offsets.Count > 0 && this.IsFilled (0)) {
//Console.WriteLine ("**** INSIDE FULL> ");
ctx.run_len = this.B - rank;
return rank - 1;
// this.run_len = this.B;
}
//Console.WriteLine ("**** OUT-SIDE FULL> B: {0}", this.B);
acc = AccStart;
ctx.Seek (0);
left = rank;
} else {
acc = this.Samples [start_index - 1];
left = rank - start_index * this.B;
//if (this.Offsets.Count > start_index && this.Offsets [start_index] == 1 + this.Offsets [start_index - 1]) {
if (this.Offsets.Count > start_index && this.IsFilled(start_index)) {
ctx.run_len = this.B - left;
return acc + left;
}
ctx.Seek (this.Offsets [start_index - 1]);
}
// for (int i = 0; i < left; i++) {
// int read = this.ReadNext (ctx);
// acc += read;
// }
while (left > 0) {
long read;
if (ctx.run_len > 0) {
read = ctx.run_len;
ctx.run_len = 0;
left -= (int)read;
if (left < 0) {
read += left;
ctx.run_len += left;
left = 0;
}
} else {
read = this.ReadNext (ctx);
left--;
}
acc += read;
}
return acc;
}
long BackendAccessRank1(long pos, out long found_pos, BitStreamCtxRL ctx)
{
if (pos < 0) {
found_pos = -1;
return 0;
}
int start_index = -1;
if (this.Samples.Count > 0) {
start_index = GenericSearch.FindFirst<long> (pos, this.Samples);
}
// reset run_len
ctx.run_len = 0;
// int count;
if (start_index < 0) {
//if (this.Offsets.Count > 0 && this.Offsets[0] == 1) {
if (this.Offsets.Count > 0 && this.IsFilled (0)) {
found_pos = pos;
return pos + 1;
} else {
ctx.Seek (0);
int count = Math.Min (this.B, this.M);
return this.SeqAccessRank1 (AccStart, pos, count, out found_pos, ctx);
}
}
int rel_rank = (start_index + 1) * this.B;
//if (this.Offsets.Count > start_index + 1 && this.Offsets[start_index + 1] == 1 + this.Offsets[start_index]) {
if (this.Offsets.Count > start_index + 1 && this.IsFilled(start_index + 1) ) {
found_pos = pos;
long diff_rank = pos - this.Samples[start_index];
return rel_rank + diff_rank;
} else {
ctx.Seek (this.Offsets[start_index]);
int count = Math.Min (this.B, this.M - rel_rank);
return rel_rank + this.SeqAccessRank1 (this.Samples[start_index], pos, count, out found_pos, ctx);
}
}
long BackendAccessRank1(long pos, out long found_pos, BitStreamCtxRL ctx)
{
if (pos < 0) {
found_pos = -1;
return 0;
}
this.ResetReader (ctx);
int start_index = -1;
if (this.Samples.Count > 0) {
start_index = GenericSearch.FindFirst<long> (pos, this.Samples);
}
int count;
if (start_index < 0) {
ctx.Seek (0);
count = Math.Min (this.B, this.M);
return this.SeqAccessRank1 (AccStart, pos, count, out found_pos, ctx);
}
ctx.Seek (this.Offsets[start_index]);
int rel_rank = (start_index + 1) * this.B;
count = Math.Min (this.B, this.M - rel_rank);
return rel_rank + this.SeqAccessRank1 (this.Samples[start_index], pos, count, out found_pos, ctx);
}
/// <summary>
/// Unlocked Select1 useful to some lowlevel operations
/// </summary>
long BackendSelect1(int rank, BitStreamCtxRL ctx)
{
if (rank < 1) {
return -1;
}
this.ResetReader(ctx);
int start_index = (rank - 1) / this.B;
long acc;
int left;
if (start_index == 0) {
acc = AccStart;
ctx.Seek (0);
left = rank;
} else {
acc = this.Samples[start_index - 1];
ctx.Seek (this.Offsets[start_index - 1]);
left = rank - start_index * this.B;
}
// int start_acc = acc;
for (int i = 0; i < left; i++) {
long read = this.ReadNext(ctx);
acc += read;
}
return acc;
}
/// <summary>
/// Extract 'count' differences starting from 'start_index', it saves the output in 'output'.
/// Returns the previous absolute value to start_index (start_index - 1), i.e. the reference
/// </summary>
public long ExtractFrom(int start_index, int count, IList<long> output)
{
long acc;
var ctx = new BitStreamCtxRL ();
if (start_index == 0) {
this.ResetReader (ctx);
acc = -1;
ctx.Seek (0);
} else {
acc = this.BackendSelect1 (start_index, ctx);
}
for (int i = 0; i < count; i++) {
long val = this.ReadNext (ctx);
if (i < output.Count) {
output[i] = val;
} else {
output.Add (val);
}
}
return acc;
}
