mirror of
https://github.com/ddnet/ddnet.git
synced 2024-11-14 03:58:18 +00:00
95 lines
2 KiB
C++
95 lines
2 KiB
C++
/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
|
|
/* If you are missing that file, acquire a complete release at teeworlds.com. */
|
|
#include <base/system.h>
|
|
|
|
#include "compression.h"
|
|
|
|
// Format: ESDDDDDD EDDDDDDD EDD... Extended, Data, Sign
|
|
unsigned char *CVariableInt::Pack(unsigned char *pDst, int i)
|
|
{
|
|
*pDst = (i>>25)&0x40; // set sign bit if i<0
|
|
i = i^(i>>31); // if(i<0) i = ~i
|
|
|
|
*pDst |= i&0x3F; // pack 6bit into dst
|
|
i >>= 6; // discard 6 bits
|
|
if(i)
|
|
{
|
|
*pDst |= 0x80; // set extend bit
|
|
while(1)
|
|
{
|
|
pDst++;
|
|
*pDst = i&(0x7F); // pack 7bit
|
|
i >>= 7; // discard 7 bits
|
|
*pDst |= (i!=0)<<7; // set extend bit (may branch)
|
|
if(!i)
|
|
break;
|
|
}
|
|
}
|
|
|
|
pDst++;
|
|
return pDst;
|
|
}
|
|
|
|
const unsigned char *CVariableInt::Unpack(const unsigned char *pSrc, int *pInOut)
|
|
{
|
|
int Sign = (*pSrc>>6)&1;
|
|
*pInOut = *pSrc&0x3F;
|
|
|
|
do
|
|
{
|
|
if(!(*pSrc&0x80)) break;
|
|
pSrc++;
|
|
*pInOut |= (*pSrc&(0x7F))<<(6);
|
|
|
|
if(!(*pSrc&0x80)) break;
|
|
pSrc++;
|
|
*pInOut |= (*pSrc&(0x7F))<<(6+7);
|
|
|
|
if(!(*pSrc&0x80)) break;
|
|
pSrc++;
|
|
*pInOut |= (*pSrc&(0x7F))<<(6+7+7);
|
|
|
|
if(!(*pSrc&0x80)) break;
|
|
pSrc++;
|
|
*pInOut |= (*pSrc&(0x7F))<<(6+7+7+7);
|
|
} while(0);
|
|
|
|
pSrc++;
|
|
*pInOut ^= -Sign; // if(sign) *i = ~(*i)
|
|
return pSrc;
|
|
}
|
|
|
|
|
|
long CVariableInt::Decompress(const void *pSrc_, int Size, void *pDst_, int DstSize)
|
|
{
|
|
const unsigned char *pSrc = (unsigned char *)pSrc_;
|
|
const unsigned char *pEnd = pSrc + Size;
|
|
int *pDst = (int *)pDst_;
|
|
int *pDstEnd = pDst + DstSize / 4;
|
|
while(pSrc < pEnd)
|
|
{
|
|
if(pDst >= pDstEnd)
|
|
return -1;
|
|
pSrc = CVariableInt::Unpack(pSrc, pDst);
|
|
pDst++;
|
|
}
|
|
return (long)((unsigned char *)pDst-(unsigned char *)pDst_);
|
|
}
|
|
|
|
long CVariableInt::Compress(const void *pSrc_, int Size, void *pDst_, int DstSize)
|
|
{
|
|
int *pSrc = (int *)pSrc_;
|
|
unsigned char *pDst = (unsigned char *)pDst_;
|
|
unsigned char *pDstEnd = pDst + DstSize;
|
|
Size /= 4;
|
|
while(Size)
|
|
{
|
|
if(pDstEnd - pDst < 6)
|
|
return -1;
|
|
pDst = CVariableInt::Pack(pDst, *pSrc);
|
|
Size--;
|
|
pSrc++;
|
|
}
|
|
return (long)(pDst-(unsigned char *)pDst_);
|
|
}
|