libsidplayfp 2.7.1
sprites.h
1/*
2 * This file is part of libsidplayfp, a SID player engine.
3 *
4 * Copyright 2011-2014 Leandro Nini <drfiemost@users.sourceforge.net>
5 * Copyright 2009-2014 VICE Project
6 * Copyright 2007-2010 Antti Lankila
7 * Copyright 2001 Simon White
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 */
23
24#ifndef SPRITES_H
25#define SPRITES_H
26
27#include <stdint.h>
28
29#include <cstring>
30
31#define SPRITES 8
32
33namespace libsidplayfp
34{
35
40{
41private:
42 const uint8_t &enable, &y_expansion;
43
44 uint8_t exp_flop;
45 uint8_t dma;
46 uint8_t mc_base[SPRITES];
47 uint8_t mc[SPRITES];
48
49public:
50 Sprites(uint8_t regs[0x40]) :
51 enable(regs[0x15]),
52 y_expansion(regs[0x17]) {}
53
54 void reset()
55 {
56 exp_flop = 0xff;
57 dma = 0;
58
59 memset(mc_base, 0, sizeof(mc_base));
60 memset(mc, 0, sizeof(mc));
61 }
62
67 void updateMc()
68 {
69 uint8_t mask = 1;
70 for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
71 {
72 if (dma & mask)
73 mc[i] = (mc[i] + 3) & 0x3f;
74 }
75 }
76
81 {
82 uint8_t mask = 1;
83 for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
84 {
85 if (exp_flop & mask)
86 {
87 mc_base[i] = mc[i];
88 if (mc_base[i] == 0x3f)
89 dma &= ~mask;
90 }
91 }
92 }
93
97 void checkExp()
98 {
99 exp_flop ^= dma & y_expansion;
100 }
101
106 {
107 for (unsigned int i = 0; i < SPRITES; i++)
108 {
109 mc[i] = mc_base[i];
110 }
111 }
112
119 void checkDma(unsigned int rasterY, uint8_t regs[0x40])
120 {
121 const uint8_t y = rasterY & 0xff;
122 uint8_t mask = 1;
123 for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
124 {
125 if ((enable & mask) && (y == regs[(i << 1) + 1]) && !(dma & mask))
126 {
127 dma |= mask;
128 mc_base[i] = 0;
129 exp_flop |= mask;
130 }
131 }
132 }
133
140 void lineCrunch(uint8_t data, unsigned int lineCycle)
141 {
142 uint8_t mask = 1;
143 for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
144 {
145 if (!(data & mask) && !(exp_flop & mask))
146 {
147 // sprite crunch
148 if (lineCycle == 14)
149 {
150 const uint8_t mc_i = mc[i];
151 const uint8_t mcBase_i = mc_base[i];
152
153 mc[i] = (0x2a & (mcBase_i & mc_i)) | (0x15 & (mcBase_i | mc_i));
154
155 // mcbase will be set from mc on the following clock call
156 }
157
158 exp_flop |= mask;
159 }
160 }
161 }
162
168 inline bool isDma(unsigned int val) const
169 {
170 return dma & val;
171 }
172};
173
174}
175
176#endif
Definition sprites.h:40
void checkExp()
Definition sprites.h:97
void checkDisplay()
Definition sprites.h:105
void updateMcBase()
Definition sprites.h:80
void checkDma(unsigned int rasterY, uint8_t regs[0x40])
Definition sprites.h:119
void updateMc()
Definition sprites.h:67
bool isDma(unsigned int val) const
Definition sprites.h:168
void lineCrunch(uint8_t data, unsigned int lineCycle)
Definition sprites.h:140