174 lines
4.1 KiB
Plaintext
174 lines
4.1 KiB
Plaintext
/*
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* This file is part of libsidplayfp, a SID player engine.
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*
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* Copyright 2011-2014 Leandro Nini <drfiemost@users.sourceforge.net>
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* Copyright 2009-2014 VICE Project
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* Copyright 2007-2010 Antti Lankila
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* Copyright 2001 Simon White
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef SPRITES_H
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#define SPRITES_H
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#include <stdint.h>
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#include <cstring>
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#define SPRITES 8
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namespace libsidplayfp
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{
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/**
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* Sprites handling.
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*/
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class Sprites
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{
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private:
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const uint8_t &enable, &y_expansion;
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uint8_t exp_flop;
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uint8_t dma;
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uint8_t mc_base[SPRITES];
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uint8_t mc[SPRITES];
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public:
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Sprites(uint8_t regs[0x40]) :
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enable(regs[0x15]),
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y_expansion(regs[0x17]) {}
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void reset()
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{
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exp_flop = 0xff;
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dma = 0;
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memset(mc_base, 0, sizeof(mc_base));
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memset(mc, 0, sizeof(mc));
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}
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/**
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* Update mc values in one pass
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* after the dma has been processed
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*/
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void updateMc()
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{
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uint8_t mask = 1;
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for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
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{
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if (dma & mask)
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mc[i] = (mc[i] + 3) & 0x3f;
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}
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}
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/**
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* Update mc base value.
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*/
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void updateMcBase()
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{
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uint8_t mask = 1;
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for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
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{
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if (exp_flop & mask)
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{
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mc_base[i] = mc[i];
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if (mc_base[i] == 0x3f)
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dma &= ~mask;
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}
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}
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}
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/**
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* Calculate sprite expansion.
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*/
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void checkExp()
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{
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exp_flop ^= dma & y_expansion;
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}
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/**
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* Check if sprite is displayed.
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*/
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void checkDisplay()
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{
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for (unsigned int i = 0; i < SPRITES; i++)
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{
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mc[i] = mc_base[i];
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}
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}
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/**
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* Calculate sprite DMA.
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*/
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void checkDma(unsigned int rasterY, uint8_t regs[0x40])
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{
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const uint8_t y = rasterY & 0xff;
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uint8_t mask = 1;
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for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
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{
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if ((enable & mask) && (y == regs[(i << 1) + 1]) && !(dma & mask))
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{
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dma |= mask;
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mc_base[i] = 0;
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exp_flop |= mask;
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}
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}
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}
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/**
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* Calculate line crunch.
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*
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* @param data the data written to the register
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* @param lineCycle current line cycle
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*/
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void lineCrunch(uint8_t data, unsigned int lineCycle)
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{
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uint8_t mask = 1;
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for (unsigned int i = 0; i < SPRITES; i++, mask <<= 1)
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{
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if (!(data & mask) && !(exp_flop & mask))
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{
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// sprite crunch
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if (lineCycle == 14)
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{
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const uint8_t mc_i = mc[i];
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const uint8_t mcBase_i = mc_base[i];
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mc[i] = (0x2a & (mcBase_i & mc_i)) | (0x15 & (mcBase_i | mc_i));
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// mcbase will be set from mc on the following clock call
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}
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exp_flop |= mask;
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}
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}
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}
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/**
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* Check if dma is active for selectod sprites.
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*
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* @param val sprites bitmask
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*/
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bool isDma(unsigned int val) const
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{
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return dma & val;
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}
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};
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}
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#endif
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