Archipelago » qemu

/*

 * Maxim MAX1110/1111 ADC chip emulation.

 *

 * Copyright (c) 2006 Openedhand Ltd.

 * Written by Andrzej Zaborowski <balrog@zabor.org>

 *

 * This code is licensed under the GNU GPLv2.

 */

#include <vl.h>

struct max111x_s {

    qemu_irq interrupt;

    uint8_t tb1, rb2, rb3;

    int cycle;

    int input[8];

    int inputs, com;

};

/* Control-byte bitfields */

#define CB_PD0                (1 << 0)

#define CB_PD1                (1 << 1)

#define CB_SGL                (1 << 2)

#define CB_UNI                (1 << 3)

#define CB_SEL0                (1 << 4)

#define CB_SEL1                (1 << 5)

#define CB_SEL2                (1 << 6)

#define CB_START        (1 << 7)

#define CHANNEL_NUM(v, b0, b1, b2)        \

                        ((((v) >> (2 + (b0))) & 4) |        \

                         (((v) >> (3 + (b1))) & 2) |        \

                         (((v) >> (4 + (b2))) & 1))

uint32_t max111x_read(void *opaque)

{

    struct max111x_s *s = (struct max111x_s *) opaque;

    if (!s->tb1)

        return 0;

    switch (s->cycle ++) {

    case 1:

        return s->rb2;

    case 2:

        return s->rb3;

    }

    return 0;

}

/* Interpret a control-byte */

void max111x_write(void *opaque, uint32_t value)

{

    struct max111x_s *s = (struct max111x_s *) opaque;

    int measure, chan;

    /* Ignore the value if START bit is zero */

    if (!(value & CB_START))

        return;

    s->cycle = 0;

    if (!(value & CB_PD1)) {

        s->tb1 = 0;

        return;

    }

    s->tb1 = value;

    if (s->inputs == 8)

        chan = CHANNEL_NUM(value, 1, 0, 2);

    else

        chan = CHANNEL_NUM(value & ~CB_SEL0, 0, 1, 2);

    if (value & CB_SGL)

        measure = s->input[chan] - s->com;

    else

        measure = s->input[chan] - s->input[chan ^ 1];

    if (!(value & CB_UNI))

        measure ^= 0x80;

    s->rb2 = (measure >> 2) & 0x3f;

    s->rb3 = (measure << 6) & 0xc0;

    if (s->interrupt)

        qemu_irq_raise(s->interrupt);

}

static struct max111x_s *max111x_init(qemu_irq cb)

{

    struct max111x_s *s;

    s = (struct max111x_s *)

            qemu_mallocz(sizeof(struct max111x_s));

    memset(s, 0, sizeof(struct max111x_s));

    s->interrupt = cb;

    /* TODO: add a user interface for setting these */

    s->input[0] = 0xf0;

    s->input[1] = 0xe0;

    s->input[2] = 0xd0;

    s->input[3] = 0xc0;

    s->input[4] = 0xb0;

    s->input[5] = 0xa0;

    s->input[6] = 0x90;

    s->input[7] = 0x80;

    s->com = 0;

    return s;

}

struct max111x_s *max1110_init(qemu_irq cb)

{

    struct max111x_s *s = max111x_init(cb);

    s->inputs = 8;

    return s;

}

struct max111x_s *max1111_init(qemu_irq cb)

{

    struct max111x_s *s = max111x_init(cb);

    s->inputs = 4;

    return s;

}

void max111x_set_input(struct max111x_s *s, int line, uint8_t value)

{

    if (line >= s->inputs) {

        printf("%s: There's no input %i\n", __FUNCTION__, line);

        return;

    }

    s->input[line] = value;

}