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

    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 <stdlib.h>
#include "ibm.h"
#include "cpu.h"
#include "x86.h"
#include "device.h"
#include "pzx.h"

char cassettefn[256];

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

} cassette_t;

extern device_t cassette_device;

static cassette_t *st_cas;

#define CAS_LOG(x) pclog x
// #define CAS_LOG(x)

/* 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(const char *filename) {
        FILE *fp;
        unsigned char magic[8];

        if (!filename)
                return;

        fp = fopen(filename, "rb");
        if (!fp) {
                /* Warn user? */
                CAS_LOG(("Failed to open cassette input %s\n", filename));
                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)) {
                const char *result;

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

                if (result) {
                        CAS_LOG(("Failed to open %s as PZX: %s\n", filename, result));
                        fclose(fp);
                        return;
                }
                strcpy(cassettefn, filename);
        }
}

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 + (cpu_get_speed() / 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) {
                CAS_LOG(("Start cassette motor\n"));
                st_cas->cycles_last = -1;
        }
        if (st_cas->motor && !on) {
                CAS_LOG(("Stop cassette motor\n"));
                st_cas->cycles_last = -1;
        }
        st_cas->motor = on;
}

static void *cassette_init(void) {
        cassette_t *cas = 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);
}

device_t cassette_device = {"Cassette", 0, cassette_init, cassette_close, NULL, NULL, NULL, NULL, NULL};
