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filter.c
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/*
* filter.c
* Copyright (C) 2003 Florian Schulze <[email protected]>
*
* This file is part of Jump'n'Bump.
*
* Jump'n'Bump is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Jump'n'Bump is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
The following scaling filter is called advancedmame2x.
The implementation found here was possible because of the great ideas of
Lucas Pope.
*/
typedef unsigned char byte;
static int scale2x_inited = 0;
static byte lookup_map[4*16];
void init_scale2x(void)
{
int i;
if (scale2x_inited)
return;
//-------------------------------------------------------------------------
// scale2x takes the following source:
// A B C
// D E F
// G H I
//
// and doubles the size of E to produce:
// E0 E1
// E2 E3
//
// E0 = D == B && B != F && D != H ? D : E;
// E1 = B == F && B != D && F != H ? F : E;
// E2 = D == H && D != B && H != F ? D : E;
// E3 = H == F && D != H && B != F ? F : E;
//
// to make this comparison regimen faster, we encode source color
// equivalency into a single byte with the getCode() macro
//
// #define getCode(b,f,h,d) ( (b == f)<<0 | (f == h)<<1 | (h == d)<<2 | (d == b)<<3 )
// encode the scale2x conditionals into a lookup code
for (i=0; i<16; i++) {
// E0 = D == B && B != F && D != H ? D : E; // 10-0 => 1000 or 1010 => 8 or A
lookup_map[0*16+i] = (i == 0x8 || i == 0xA) ? 0 : 1;
// E1 = B == F && B != D && F != H ? F : E; // 0-01 => 0101 or 0001 => 5 or 1
lookup_map[1*16+i] = (i == 0x5 || i == 0x1) ? 2 : 1;
// E2 = D == H && D != B && H != F ? D : E; // 010- => 0101 or 0100 => 5 or 4
lookup_map[2*16+i] = (i == 0x4 || i == 0x5) ? 0 : 1;
// E3 = H == F && D != H && B != F ? F : E; // -010 => 1010 or 0010 => A or 2
lookup_map[3*16+i] = (i == 0xA || i == 0x2) ? 2 : 1;
}
}
void do_scale2x(unsigned char *src,
int src_width,
int src_height,
unsigned char *dst) {
int dst_width = src_width * 2;
int dst_height = src_height * 2;
int x, y;
for (x = 0; x < dst_width; ++x) {
for (y = 0; y < dst_height; ++y) {
int src_x = x / 2;
int src_y = y / 2;
dst[y * dst_width + x] = src[src_y * src_width + src_x];
}
}
}
#if 0
void do_scale2x(unsigned char *src,
int src_width,
int src_height,
unsigned char *dst)
{
int x;
int y;
int dst_width = src_width * 2;
int dst_height = src_height * 2;
int code;
byte rowColors[3];
byte *e0;
byte *e1;
byte *e2;
byte *e3;
if (!scale2x_inited)
init_scale2x();
// special top case - b is always unknown
{
byte *d;
byte *e;
byte *f;
byte *h;
e0 = &dst[0];
e1 = &dst[1];
e2 = &dst[dst_width];
e3 = &dst[dst_width + 1];
e = &src[0];
f = &src[1];
h = &src[src_width];
// special left case - d is unknown
rowColors[0] = *e;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*f == *h)<<1 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
e++; f++; h++;
d = &src[src_width]; // (src_width - 1) + 1
e0+=2; e1+=2; e2+=2; e3+=2;
// normal case
for (x=1; x<(src_width-1); x++) {
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*f == *h)<<1 | (*h == *d)<<2 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
d++; e++; f++; h++;
e0+=2; e1+=2; e2+=2; e3+=2;
}
// special right case - f is unknown
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *e;
code = ( (*h == *d)<<2 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
}
// top and bottom always known
for (y=1; y<(src_height-1); y++) {
byte *b;
byte *d;
byte *e;
byte *f;
byte *h;
e0 = &dst[y*dst_width*2];
e1 = &dst[y*dst_width*2 + 1];
e2 = &dst[y*dst_width*2 + dst_width];
e3 = &dst[y*dst_width*2 + dst_width + 1];
b = &src[y * src_width - src_width];
e = &src[y * src_width];
f = &src[y * src_width + 1];
h = &src[y * src_width + src_width];
// special left case - d is unknown
rowColors[0] = *e;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*b == *f)<<0 | (*f == *h)<<1 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
b++; e++; f++; h++;
d = &src[y * src_width]; // (y * src_width - 1) + 1
e0+=2; e1+=2; e2+=2; e3+=2;
// normal case
for (x=1; x<(src_width-1); x++) {
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*b == *f)<<0 | (*f == *h)<<1 | (*h == *d)<<2 | (*d == *b)<<3 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
b++; d++; e++; f++; h++;
e0+=2; e1+=2; e2+=2; e3+=2;
}
// special right case - f is unknown
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *e;
code = ( (*h == *d)<<2 | (*d == *b)<<3 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
}
// special bottom case - h is always unknown
{
byte *b;
byte *d;
byte *e;
byte *f;
e0 = &dst[y*dst_width*2];
e1 = &dst[y*dst_width*2 + 1];
e2 = &dst[y*dst_width*2 + dst_width];
e3 = &dst[y*dst_width*2 + dst_width + 1];
b = &src[y * src_width - src_width];
e = &src[y * src_width];
f = &src[y * src_width + 1];
// special left case - d is unknown
rowColors[0] = *e;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*b == *f)<<0 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
b++; e++; f++;
d = &src[y * src_width]; // (y * src_width - 1) + 1
e0+=2; e1+=2; e2+=2; e3+=2;
// normal case
for (x=1; x<(src_width-1); x++) {
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *f;
code = ( (*b == *f)<<0 | (*d == *b)<<3 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
b++; d++; e++; f++;
e0+=2; e1+=2; e2+=2; e3+=2;
}
// special right case - f is unknown
rowColors[0] = *d;
rowColors[1] = *e;
rowColors[2] = *e;
code = ( (*d == *b)<<3 );
*e0 = rowColors[lookup_map[0*16+code]];
*e1 = rowColors[lookup_map[1*16+code]];
*e2 = rowColors[lookup_map[2*16+code]];
*e3 = rowColors[lookup_map[3*16+code]];
}
}
#endif