86Box/src/cassette/cassette.c

/************************************************************************

    PCEM: IBM 5150 Cassette support

    Copyright (C) 2019  John Elliott <seasip.webmaster@gmail.com>

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

*************************************************************************/

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <wchar.h>
#define HAVE_STDARG_H
#include "../86box.h"
#include "../device.h"
#include "../cpu/cpu.h"
#include "../machine/machine.h"
#include "../ppi.h"
#include "../ui.h"
#include "../plat.h"
#include "pzx.h"
#include "cassette.h"

typedef struct cassette_t 
{
	uint8_t motor;		/* Motor status */
	pzxfile_t pzx;
	int cycles_last;	/* Cycle count at last cassette poll */

} cassette_t;

wchar_t cassettefn[256];

static cassette_t *st_cas;


#ifdef ENABLE_CASSETTE_LOG
int cassette_do_log = ENABLE_CASSETTE_LOG;


static void
cassette_log(const char *fmt, ...)
{
   va_list ap;

   if (cassette_do_log)
   {
	va_start(ap, fmt);
	pclog_ex(fmt, ap);
	va_end(ap);
   }
}
#else
#define cassette_log(fmt, ...)
#endif


/* The PCEM CPU uses IBM cycles (4.77MHz). PZX uses Spectrum cycles (3.5MHz)
 * so scale accordingly. */
static int32_t 
pzx_cycles(int32_t pc)
{
	double d = pc;
	
	return (int32_t)(((d * 3.5) / 4.772728) + 0.5);
}

void 
cassette_eject(void)
{
	if (st_cas->pzx.input) {
		pzx_close(&st_cas->pzx);
	}
	cassettefn[0] = 0;
}

void 
cassette_load(wchar_t *fn)
{
	FILE *fp;
	unsigned char magic[8];

	if (!fn) 
		return;

	fp = plat_fopen(fn, L"rb");
	if (!fp) {
		/* Warn user? */
		cassette_log("Failed to open cassette input %s\n", fn);
		return;
	}
	memset(magic, 0, sizeof(magic));
	fread(magic, 1, sizeof(magic), fp);	

	/* Check for PZX signature. In due course support could be added for
	 * other formats like TZX */
	if (!memcmp(magic, "PZXT", 4)) {
		wchar_t *result;

		result = pzx_open(&st_cas->pzx, fp);

		if (result) {
			cassette_log("Failed to open %s as PZX: %s\n",
				fn, result);
			fclose(fp);
			return;			
		}
		wcscpy(cassettefn, fn);
	}
}


uint8_t 
cassette_input(void)
{
	int ticks;

	/* While motor is off, result is loopback */
	if (!st_cas->motor)
		return ppispeakon;
	/* If there is no tapefile open don't try to extract data */
	if (st_cas->pzx.input == NULL) 
		return 0;
	/* Otherwise see how many ticks there have been since the last input */
	if (st_cas->cycles_last == -1) 
		st_cas->cycles_last = cycles;
	if (cycles <= st_cas->cycles_last)
		ticks = (st_cas->cycles_last - cycles);
	else
		ticks = (st_cas->cycles_last + (machines[machine].cpu[cpu_manufacturer].cpus[cpu_effective].rspeed / 100) - cycles);
	st_cas->cycles_last = cycles;
	
	return pzx_advance(&st_cas->pzx, pzx_cycles(ticks));	
}



void 
cassette_set_motor(uint8_t on)
{
	if (on && !st_cas->motor) {
		cassette_log("Start cassette motor\n");
		st_cas->cycles_last = -1;
	}
	if (st_cas->motor && !on) {
		cassette_log("Stop cassette motor\n");
		st_cas->cycles_last = -1;
	}
	st_cas->motor = on;
}


static void 
*cassette_init(const device_t *info)
{
	cassette_t *cas = (cassette_t *)malloc(sizeof(cassette_t));
	memset(cas, 0, sizeof(cassette_t));
	pzx_init(&cas->pzx);

	st_cas = cas;
	return cas;
}


static void 
cassette_close(void *p)
{
	cassette_t *cas = (cassette_t *)p;

	pzx_close(&cas->pzx);

	free(cas);
}


const device_t cassette_device = {
	"IBM PC 5150 Cassette",
	0,
	0,
	cassette_init,
	cassette_close,
	NULL,
	NULL,
	NULL,
	NULL
};