73 lines
2.0 KiB
C
73 lines
2.0 KiB
C
/* FCE Ultra - NES/Famicom Emulator
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*
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* Copyright notice for this file:
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* Copyright (C) 2025 NewRisingSun
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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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#include "mapinc.h"
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#include "asic_vrc2and4.h"
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static uint8 irqEnabled;
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static uint16 irqCounterLow;
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static uint8 irqCounterHigh;
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static SFORMAT UNLTH21311_stateRegs[] ={
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{ &irqEnabled, 1, "IRQE" },
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{ &irqCounterLow, 2 | FCEUSTATE_RLSB, "CNTL" },
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{ &irqCounterHigh, 1, "CNTH" },
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{ 0 }
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};
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static void sync () {
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VRC24_syncPRG(0x01F, 0x000);
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VRC24_syncCHR(0x1FF, 0x000);
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VRC24_syncMirror();
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}
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DECLFW(UNLTH21311_writeIRQ) {
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switch(A &3) {
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case 0: X6502_IRQEnd(FCEU_IQEXT);
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irqEnabled =0;
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irqCounterLow =0;
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break;
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case 1: irqEnabled =1;
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break;
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case 3: irqCounterHigh =V >>4;
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break;
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}
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}
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void FP_FASTAPASS(1) UNLTH21311_cpuCycle(int a) {
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while (a--) if (irqEnabled) {
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if ((++irqCounterLow &4095) ==2048) irqCounterHigh--;
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if (!irqCounterHigh && (irqCounterLow &4095) <2048) X6502_IRQBegin(FCEU_IQEXT);
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}
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}
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void UNLTH21311_power(void) {
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irqEnabled =irqCounterLow =irqCounterHigh =0;
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VRC24_power();
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SetWriteHandler(0xF000, 0xFFFF, UNLTH21311_writeIRQ);
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}
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void UNLTH21311_Init (CartInfo *info) {
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VRC2_init(info, sync, 0x01, 0x02, NULL, NULL, NULL, NULL);
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AddExState(UNLTH21311_stateRegs, ~0, 0, 0);
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info->Power =UNLTH21311_power;
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MapIRQHook =UNLTH21311_cpuCycle;
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}
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