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/*
* Buffered Filter
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/buf_filt.h>
#include <botan/mem_ops.h>
#include <botan/internal/rounding.h>
#include <botan/exceptn.h>
namespace Botan {
/*
* Buffered_Filter Constructor
*/
Buffered_Filter::Buffered_Filter(size_t b, size_t f) :
m_main_block_mod(b), m_final_minimum(f)
{
if(m_main_block_mod == 0)
throw Invalid_Argument("m_main_block_mod == 0");
if(m_final_minimum > m_main_block_mod)
throw Invalid_Argument("m_final_minimum > m_main_block_mod");
m_buffer.resize(2 * m_main_block_mod);
m_buffer_pos = 0;
}
/*
* Buffer input into blocks, trying to minimize copying
*/
void Buffered_Filter::write(const uint8_t input[], size_t input_size)
{
if(!input_size)
return;
if(m_buffer_pos + input_size >= m_main_block_mod + m_final_minimum)
{
size_t to_copy = std::min<size_t>(m_buffer.size() - m_buffer_pos, input_size);
copy_mem(&m_buffer[m_buffer_pos], input, to_copy);
m_buffer_pos += to_copy;
input += to_copy;
input_size -= to_copy;
size_t total_to_consume =
round_down(std::min(m_buffer_pos,
m_buffer_pos + input_size - m_final_minimum),
m_main_block_mod);
buffered_block(m_buffer.data(), total_to_consume);
m_buffer_pos -= total_to_consume;
copy_mem(m_buffer.data(), m_buffer.data() + total_to_consume, m_buffer_pos);
}
if(input_size >= m_final_minimum)
{
size_t full_blocks = (input_size - m_final_minimum) / m_main_block_mod;
size_t to_copy = full_blocks * m_main_block_mod;
if(to_copy)
{
buffered_block(input, to_copy);
input += to_copy;
input_size -= to_copy;
}
}
copy_mem(&m_buffer[m_buffer_pos], input, input_size);
m_buffer_pos += input_size;
}
/*
* Finish/flush operation
*/
void Buffered_Filter::end_msg()
{
if(m_buffer_pos < m_final_minimum)
throw Exception("Buffered filter end_msg without enough input");
size_t spare_blocks = (m_buffer_pos - m_final_minimum) / m_main_block_mod;
if(spare_blocks)
{
size_t spare_bytes = m_main_block_mod * spare_blocks;
buffered_block(m_buffer.data(), spare_bytes);
buffered_final(&m_buffer[spare_bytes], m_buffer_pos - spare_bytes);
}
else
{
buffered_final(m_buffer.data(), m_buffer_pos);
}
m_buffer_pos = 0;
}
}
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