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/*
* dma.c - Utility functions for DMA hosts.
*
* Written by
* Andreas Boose <viceteam@t-online.de>
*
* This file is part of VICE, the Versatile Commodore Emulator.
* See README for copyright notice.
*
* This program 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.
*
* This program 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.
*
*/
#include "vice.h"
#include "6510core.h"
#include "debug.h"
#include "dma.h"
#include "interrupt.h"
#include "types.h"
/* Asynchronously steal `num' cycles from the CPU, starting from cycle
`start_clk'. */
void dma_maincpu_steal_cycles(CLOCK start_clk, int num, CLOCK sub)
{
CLOCK irq_sub = 0;
CLOCK nmi_sub = 0;
unsigned int cycles_left_to_trigger_irq;
interrupt_cpu_status_t *cs = maincpu_int_status;
CLOCK dma_start;
if (num == 0)
return;
dma_start = start_clk + sub;
if (start_clk == cs->last_stolen_cycles_clk)
cs->num_last_stolen_cycles += num;
else
cs->num_last_stolen_cycles = num;
/*log_debug("START %i NUM %i SUB %i MAIN %i DMAST %i",
start_clk, num, sub, maincpu_clk, dma_start);*/
cs->num_cycles_left[cs->num_dma_per_opcode] = maincpu_clk - dma_start;
cs->dma_start_clk[cs->num_dma_per_opcode] = dma_start;
(cs->num_dma_per_opcode)++;
#ifdef DEBUG
if (debug.maincpu_traceflg)
debug_dma("VICII", start_clk, num);
#endif
cycles_left_to_trigger_irq =
(OPINFO_DELAYS_INTERRUPT(*cs->last_opcode_info_ptr) ? 2 : 1);
if (cs->irq_clk >= start_clk
&& dma_start == (maincpu_clk - cycles_left_to_trigger_irq)
&& cs->num_dma_per_opcode == 1) {
/*log_debug("DECR");*/
irq_sub = 1;
}
if (cs->nmi_clk >= start_clk
&& dma_start == (maincpu_clk - cycles_left_to_trigger_irq)
&& cs->num_dma_per_opcode == 1) {
/*log_debug("DECR");*/
nmi_sub = 1;
}
maincpu_clk += num;
cs->last_stolen_cycles_clk = dma_start + num;
/*log_debug("IRQCLK %i LASTSTOLEN %i",
cs->irq_clk, cs->last_stolen_cycles_clk);*/
if (cs->irq_clk > dma_start)
cs->irq_clk = cs->last_stolen_cycles_clk;
else
cs->irq_clk += num;
if (cs->nmi_clk > dma_start)
cs->nmi_clk = cs->last_stolen_cycles_clk;
else
cs->nmi_clk += num;
cs->irq_clk -= irq_sub;
cs->nmi_clk -= nmi_sub;
/*log_debug("NEWIRQCLK %i", cs->irq_clk);*/
}
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