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Initial fixed huffman coding for png.

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This commit is contained in:
James Grogan 2022-11-28 10:16:04 +00:00
parent e4f9393ee7
commit 7f5009fb5e
39 changed files with 1294 additions and 440 deletions
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45
src/core/ByteUtils.cpp
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@ -26,7 +26,20 @@ unsigned char ByteUtils::getByteN(uint32_t input, unsigned n)
return (input << 8*n) >> 24;
}
unsigned char ByteUtils::getLowerNBits(unsigned char input, unsigned num)
unsigned char ByteUtils::mirror(unsigned char byte, unsigned length)
{
unsigned char ret{0};
for(unsigned idx=0; idx<length; idx++)
{
if (getBitN(byte, length - 1 - idx))
{
ret |= (0x01 << idx);
}
}
return ret;
}
unsigned char ByteUtils::getLowerNBits(uint32_t input, unsigned num)
{
switch (num)
{
@ -81,7 +94,7 @@ unsigned char ByteUtils::getMBitsAtN(unsigned char input, unsigned m, unsigned n
}
}
unsigned char ByteUtils::getBitN(unsigned char input, unsigned n)
bool ByteUtils::getBitN(uint32_t input, unsigned n)
{
return input & (1 << n);
}
@ -105,12 +118,34 @@ unsigned char ByteUtils::getFromString(const std::string& string)
return ret;
}
std::string ByteUtils::toString(unsigned char c)
std::string ByteUtils::toString(uint32_t input, unsigned length)
{
std::string ret;
for(unsigned idx=0; idx<8; idx++)
std::string working;
for(unsigned idx=0; idx<length; idx++)
{
ret += getBitN(c, 7 - idx) ? '1' : '0';
if (idx > 0 && idx % 8 == 0)
{
if (ret.empty())
{
ret = working;
}
else
{
ret = working + '-' + ret;
}
working = "";
}
working += getBitN(input, 7 - idx) ? '1' : '0';
}
if (length <= 8)
{
ret = working;
}
else if(!working.empty())
{
ret = working + '-' + ret;
}
return ret;
}