ddnet/src/engine/compression.c
2007-09-09 18:21:14 +00:00

147 lines
2.5 KiB
C

#include "system.h"
#include <string.h>
/* Format: ESDDDDDD EDDDDDDD EDD... Extended, Data, Sign */
unsigned char *vint_pack(unsigned char *dst, int i)
{
*dst = (i>>25)&0x40; /* set sign bit if i<0 */
i = i^(i>>31); /* if(i<0) i = ~i */
*dst |= i&0x3F; /* pack 6bit into dst */
i >>= 6; /* discard 6 bits */
if(i)
{
*dst |= 0x80; /* set extend bit */
while(1)
{
dst++;
*dst = i&(0x7F); /* pack 7bit */
i >>= 7; /* discard 7 bits */
*dst |= (i!=0)<<7; /* set extend bit (may branch) */
if(!i)
break;
}
}
dst++;
return dst;
}
const unsigned char *vint_unpack(const unsigned char *src, int *i)
{
int sign = (*src>>6)&1;
*i = *src&0x3F;
do
{
if(!(*src&0x80)) break;
src++;
*i |= (*src&(0x7F))<<(6);
if(!(*src&0x80)) break;
src++;
*i |= (*src&(0x7F))<<(6+7);
if(!(*src&0x80)) break;
src++;
*i |= (*src&(0x7F))<<(6+7+7);
if(!(*src&0x80)) break;
src++;
*i |= (*src&(0x7F))<<(6+7+7+7);
} while(0);
src++;
*i ^= -sign; /* if(sign) *i = ~(*i) */
return src;
}
long intpack_decompress(const void *src_, int size, void *dst_)
{
const unsigned char *src = (unsigned char *)src_;
const unsigned char *end = src + size;
int *dst = (int *)dst_;
while(src < end)
{
src = vint_unpack(src, dst);
dst++;
}
return (long)((unsigned char *)dst-(unsigned char *)dst_);
}
long intpack_compress(const void *src_, int size, void *dst_)
{
int *src = (int *)src_;
unsigned char *dst = (unsigned char *)dst_;
size /= 4;
while(size)
{
dst = vint_pack(dst, *src);
size--;
src++;
}
return (long)(dst-(unsigned char *)dst_);
}
/* */
long zerobit_compress(const void *src_, int size, void *dst_)
{
unsigned char *src = (unsigned char *)src_;
unsigned char *dst = (unsigned char *)dst_;
while(size)
{
unsigned char bit = 0x80;
unsigned char mask = 0;
int dst_move = 1;
int chunk = size < 8 ? size : 8;
int b;
size -= chunk;
for(b = 0; b < chunk; b++, bit>>=1)
{
if(*src)
{
dst[dst_move] = *src;
mask |= bit;
dst_move++;
}
src++;
}
*dst = mask;
dst += dst_move;
}
return (long)(dst-(unsigned char *)dst_);
}
long zerobit_decompress(const void *src_, int size, void *dst_)
{
unsigned char *src = (unsigned char *)src_;
unsigned char *dst = (unsigned char *)dst_;
unsigned char *end = src + size;
while(src != end)
{
unsigned char bit = 0x80;
unsigned char mask = *src++;
int b;
for(b = 0; b < 8; b++, bit>>=1)
{
if(mask&bit)
*dst++ = *src++;
else
*dst++ = 0;
}
}
long l = (long)(dst-(unsigned char *)dst_);
return l;
}