88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
#include <iostream>
|
|
#include <bitset>
|
|
#include "bitstream.h"
|
|
|
|
#define min(x,y) (((x) > (y)) ? (y) : (x))
|
|
|
|
// i.e when stream is 0b12345678 0bABCDEFGH and command is
|
|
// to read 12 bits:
|
|
// out = 00000000 00000000 0000EFGH 12345678
|
|
// to read 2 bits:
|
|
// out = 00000000 00000000 00000000 00000078
|
|
int ibitstream::getbits(size_t n) {
|
|
std::cerr << "To read " << n << " count: " << this->count << " " << this->cache << std::endl;
|
|
int out = 0, read = 0, to_read;
|
|
|
|
if (n > 32 || n < 0) {
|
|
throw std::runtime_error("When reading bits from bitstream n must be <= 32");
|
|
}
|
|
|
|
// read to cache
|
|
if (this->count == -1 || this->count >= 8) {
|
|
if (!(this->is >> cache)) throw std::runtime_error("Stream EOF");
|
|
this->count = 0;
|
|
}
|
|
|
|
while (n > 0) {
|
|
to_read = min(n, 8 - this->count);
|
|
std::cerr << "Iter n: " << n << " count: " << this->count << " "
|
|
<< this->cache << " to_read: " << to_read << " already read: " << read << std::endl;
|
|
|
|
// cache & 0b11111000 if count = 3;
|
|
// cache & 0b10000000 if count = 7;
|
|
// cache & 0b11111111 if count = 0, etc;
|
|
uint8_t mask = (((1 << to_read) - 1) << this->count);
|
|
out |= ((cache & mask) >> this->count) << read;
|
|
|
|
std::cerr << "Read result: " << std::bitset<8>((cache & mask) >> this->count) << " " << std::bitset<32>(((cache & mask) >> this->count) << read) << std::endl;
|
|
|
|
this->count += to_read;
|
|
read += to_read;
|
|
n -= to_read;
|
|
|
|
if (this->count == 8){
|
|
// read another byte
|
|
if (!(this->is >> cache)) throw std::runtime_error("Stream EOF");
|
|
this->count = 0;
|
|
}
|
|
}
|
|
|
|
return out;
|
|
}
|
|
|
|
void obitstream::writebits(short bits, size_t n) {
|
|
std::cerr << "Write: " << std::bitset<16>(bits) << " n: " << n << " count: " << this->count << " cache: " << std::bitset<8>(this->cache) << std::endl;
|
|
int written = 0, to_write;
|
|
while (n > 0) {
|
|
to_write = min(n, 8 - this->count);
|
|
|
|
uint8_t chunk = (bits & (((1 << to_write) - 1) << written)) >> written;
|
|
this->cache |= (chunk << this->count);
|
|
|
|
this->count += to_write;
|
|
written += to_write;
|
|
n -= to_write;
|
|
|
|
if (this->count == 8){
|
|
// flush chunk
|
|
std::cerr << "Flush: " << std::bitset<8>(this->cache) << std::endl;
|
|
|
|
os << this->cache;
|
|
os.flush();
|
|
|
|
this->count = 0;
|
|
this->cache = 0;
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
void obitstream::flush() {
|
|
std::cerr << "Flush: " << std::bitset<8>(this->cache) << std::endl;
|
|
os << this->cache;
|
|
os.flush();
|
|
|
|
this->cache = 0;
|
|
this->count = 0;
|
|
}
|