ImageEncoder/BitStream.cpp at master · ThenTech/ImageEncoder · GitHub

History

102 lines (73 loc) · 2.92 KB

Raw

100

101

#include "BitStream.hpp"

namespace util {

const uint8_t bitmasks[] = {0, 128, 192, 224, 240, 248, 252, 254};

BitStreamReader::BitStreamReader(uint8_t *b, size_t s) : BitStream(b, s, 0, false) {}

BitStreamReader::~BitStreamReader() {}

void BitStreamReader::flush() {

this->position = this->get_last_byte_position() * 8u;

}

uint8_t BitStreamReader::get_bit() {

const size_t current_start_byte = this->position / 8u;

if (current_start_byte >= this->get_size()) {

// Prevent reading byte outside of array (-> Valgrind flagged)

return 0u;

}

const size_t bits_taken = this->position % 8;

const uint8_t value = this->buffer[current_start_byte];

this->position++;

return (value & (1 << (7 - bits_taken))) != 0;

}

uint32_t BitStreamReader::get(size_t l) {

uint32_t value = 0;

for (size_t i = 0; i < l; i++) {

const uint32_t v = this->get_bit();

value |= v << (l - i - 1);

//printf("%s %d pos %d i %d v %d value %x\n", __func__, __LINE__, position, i, v, value);

}

return value;

}

////////////////////////////////////////////////////////////////////////////////////

BitStreamWriter::BitStreamWriter(size_t s)

: BitStream(util::allocArray<uint8_t>(s), s, 0, true)

{

//printf("Allocated buffer of size: %d\n", s);

}

BitStreamWriter::BitStreamWriter(uint8_t *b, size_t s) : BitStream(b, s, 0, false) {}

BitStreamWriter::~BitStreamWriter() {}

void BitStreamWriter::flush() {

if (this->position % 8 != 0) {

this->buffer[this->position / 8] &= bitmasks[this->position % 8];

this->position += 8 - (this->position % 8);

}

void BitStreamWriter::put_bit(int8_t value) {

const size_t bits_taken = this->position % 8;

if (value) {

this->buffer[this->position / 8] |= 1 << (7 - bits_taken);

} else {

this->buffer[this->position / 8] &= ~(1 << (7 - bits_taken));

}

this->position++;

}

void BitStreamWriter::put(size_t length, uint32_t value) {

for (size_t p = 0; p < length; p++) {

put_bit(1 & (value >> (length - 1 - p)));

}

void write(FILE *f, const BitStreamWriter &b) {

const size_t position = b.get_position();

const uint8_t *buffer = b.get_buffer();

fwrite(buffer, 1, position / 8, f);

if (position % 8 != 0) {

fwrite(buffer + position / 8, 1, 1, f);

}

void write(std::ofstream &fs, const BitStreamWriter &b) {

const size_t position = b.get_position();

const uint8_t *buffer = b.get_buffer();

fs.write(reinterpret_cast<const char*>(buffer), position / 8);

if (position % 8 != 0) {

fs.write(reinterpret_cast<const char*>(buffer + position / 8), 1);

}

ImageEncoder/BitStream.cpp at master · ThenTech/ImageEncoder · GitHub

Expand file tree

Breadcrumbs

BitStream.cpp

Latest commit

History

Breadcrumbs

BitStream.cpp

File metadata and controls