/*
costs per 4 pixels: (# = black)
1 bit:
----
4 bits:
#---
##--
--##
####
5 bits:
---#
#-##
-###
-#--
--#-
6 bits:
#-#-
-##-
###-
#--#
-#-#
##-#
*/
#include <stdio.h>
void LogoPackBits(unsigned char *srcp, unsigned char *destp)
{
unsigned int destbit = 0;
unsigned int destvalue = 0;
unsigned int d = 0;
for (unsigned int s=0; s<1664; s++)
{
if (srcp[s]) destvalue |= 1<<destbit;
if (++destbit == 8)
{
destp[d++] = destvalue;
destbit = 0;
destvalue = 0;
}
}
}
struct LogoPattern
{
unsigned int value;
unsigned int bits;
} logoPatterns[16] =
{
{0x01, 1}, {0x06, 4}, {0x0A, 5}, {0x04, 4},
{0x02, 5}, {0x1E, 6}, {0x16, 6}, {0x06, 6},
{0x06, 5}, {0x1F, 6}, {0x17, 6}, {0x07, 6},
{0x02, 4}, {0x0E, 5}, {0x07, 5}, {0x00, 4},
};
int LogoCompress(unsigned char *src, unsigned char *dst)
{
unsigned int data_out = 0;
unsigned int outbit = 31;
unsigned int outbitcnt = 0;
for (int i=0; i<212; i++)
{
unsigned int data = *src++;
for (int j=0; j<8; j+=4)
{
LogoPattern &lh = logoPatterns[data >> j & 0xF];
outbitcnt += lh.bits;
for (int b=lh.bits-1; b>=0; b--)
{
data_out |= (lh.value >> b & 1) << outbit;
if (outbit == 0)
{
if (outbitcnt <= 156*8)
{
*dst++ = data_out >> 0;
*dst++ = data_out >> 8;
*dst++ = data_out >> 16;
*dst++ = data_out >> 24;
}
outbit = 31;
data_out = 0;
}
else
{
outbit--;
}
}
}
}
if (outbit != 31)
{
if (outbitcnt <= 156*8)
{
*dst++ = data_out >> 0;
*dst++ = data_out >> 8;
*dst++ = data_out >> 16;
*dst++ = data_out >> 24;
}
}
return 156*8 - outbitcnt;
};
void LogoDiff(unsigned char *srcp, unsigned char *dstp)
{
unsigned int *intp_dst = (unsigned int *)dstp;
*intp_dst++ = 0xD0 << 8 | 0x80 | 2; // header
unsigned short *shortp_dst = (unsigned short *)intp_dst;
unsigned short *shortp_src = (unsigned short *)srcp;
unsigned short prev = 0;
for (unsigned int i=0; i<0xD0; i+=2)
{
*shortp_dst++ = *shortp_src - prev;
prev = *shortp_src++;
}
}
int LogoConvert(unsigned char *srcp, unsigned char *dstp, unsigned char white)
{
// convert to tiles
unsigned char tiles[1664];
for (int ty=0; ty<2; ty++)
{
for (int y=0; y<8; y++)
{
for (int tx=0; tx<13; tx++)
{
for (int x=0; x<8; x++)
{
tiles[(ty*13 + tx)*64 + y*8 + x] = (*srcp++ == white) ? 0 : 1;
}
}
}
}
// bitpack
unsigned char bitpacked[1664/8];
LogoPackBits(tiles, bitpacked);
// diff
unsigned char diffed[4 + 1664/8];
LogoDiff(bitpacked, diffed);
// compress
int r = LogoCompress(diffed, dstp);
if (r < 0)
{
fprintf(stderr, "Compressed logo is %u bit(s) too big. Please simplify.\n", -r);
return -1;
}
return 0;
}
