1 /*
2 * Copyright 2004, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
3 * Copyright 2015, Augustin Cavalier <waddlesplash>. All rights reserved.
4 * Distributed under the terms of the MIT License.
5 *
6 * Effect from corTeX / Optimum.
7 */
8
9 #include <SupportDefs.h>
10
11 #include "Draw.h"
12
13
14 // Hand-translated from x86 assembly.
15 /* memshset (char *dst, int center_shade,int fixed_shade, int length_2) */
16 /* dst is the *center* of the dst segment */
17 /* center shade is the initial color (at center) (!! 8:8 also) */
18 /* fixed_shade is the fixed point increment (8:8) */
19 /* length_2 is the 1/2 length to set (to the left, and to the right) */
20
21 /* a memaddshadedset function (or something like that ) */
memshset(char * dstParam,int center_shade,int fixed_shade,int half_length)22 void memshset(char* dstParam, int center_shade, int fixed_shade, int half_length)
23 {
24 unsigned char* dst;
25 unsigned char* source;
26 int offset;
27
28 if (half_length == 0)
29 return;
30
31 dst = (unsigned char*)dstParam;
32 source = dst;
33 dst -= half_length; // Left segment
34 source += half_length; // Right segment
35 source++; // Don't overlap at middle
36
37 offset = half_length;
38 offset = -offset;
39 offset--; // For in-advance incl in loop
40
41 do {
42 int tmp;
43 center_shade += fixed_shade; // Increment color.
44 center_shade &= 0xFFFF; // Mask so we can do overflow tests.
45 offset++;
46
47 tmp = dst[half_length] + (center_shade >> 8); // Increment left pixel.
48 // Did it overflow?
49 if (tmp & 0xFF00)
50 dst[half_length] = 255;
51 else
52 dst[half_length] = tmp;
53
54 tmp = source[offset] + (center_shade >> 8); // Increment right pixel.
55 if (tmp & 0xFF00)
56 source[offset] = 255;
57 else
58 source[offset] = tmp;
59 } while (--half_length != 0);
60 }
61
62
63 /* do the "motion blur" (actually the pixel fading) */
mblur(char * srcParam,int nbpixels)64 void mblur(char* srcParam, int nbpixels)
65 {
66 unsigned int clear1UpperBit = 0x7f7f7f7f;
67 unsigned int clear3UpperBits = 0x1f1f1f1f;
68 unsigned int* src = (unsigned int*)srcParam;
69
70 if ((nbpixels >>= 2) == 0)
71 return;
72
73 do {
74 unsigned int eax, ebx;
75 eax = *src;
76
77 ebx = eax;
78 eax >>= 1;
79
80 ebx >>= 3;
81 eax &= clear1UpperBit;
82
83 ebx &= clear3UpperBits;
84
85 eax += ebx;
86 *src = eax;
87 src++;
88 } while (--nbpixels != 0);
89 }
90