path: root/src/cpcout.c

/*

    casm - Simple, portable assembler

    Copyright (C) 2003-2015  Ian Cowburn (ianc@noddybox.co.uk)

    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 3 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, see <http://www.gnu.org/licenses/>.

    -------------------------------------------------------------------------

    Commodore CPC tape output handler.

*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "global.h"
#include "codepage.h"
#include "cpcout.h"
#include "expr.h"


/* ---------------------------------------- MACROS & TYPES
*/

enum option_t
{
    OPT_START_ADDR,
};

static const ValueTable option_set[] =
{
    {"cpc-start",  OPT_START_ADDR},
    {NULL}
};

typedef struct
{
    int         start_addr;
} Options;

static Options options = {-1};

/* ---------------------------------------- PRIVATE FUNCTIONS
*/

static int PokeB(Byte *mem, int addr, Byte b)
{
    mem[addr++] = b;
    return (addr % 0x10000);
}


static int PokeW(Byte *mem, int addr, int w)
{
    addr = PokeB(mem, addr, w & 0xff);
    return PokeB(mem, addr, (w & 0xff00) >> 8);
}


static int PokeS(Byte *mem, int addr, const char *str)
{
    while(*str)
    {
        addr = PokeB(mem, addr, CodeFromNative(CP_ASCII, *str++));
    }

    return addr;
}


static void WriteByte(FILE *fp, Byte b)
{
    putc(b, fp);
}


static void WriteWord(FILE *fp, int w)
{
    WriteByte(fp, w & 0xff);
    WriteByte(fp, (w & 0xff00) >> 8);
}


static void WriteLong(FILE *fp, unsigned long l)
{
    int f;

    for(f = 0; f < 4; f++)
    {
        WriteByte(fp, l & 0xff);
        l >>= 8u;
    }
}


static void WriteString(FILE *fp, const char *p, int len,
                        Byte fill, Codepage cp)
{
    while(len--)
    {
        WriteByte(fp, *p ? CodeFromNative(cp, *p++) : CodeFromNative(cp, fill));
    }
}


/* ---------------------------------------- INTERFACES
*/
const ValueTable *CPCOutputOptions(void)
{
    return option_set;
}

CommandStatus CPCOutputSetOption(int opt, int argc, char *argv[], int quoted[],
                                 char *err, size_t errsize)
{
    CommandStatus stat = CMD_OK;

    CMD_ARGC_CHECK(1);

    switch(opt)
    {
        case OPT_START_ADDR:
            CMD_EXPR(argv[0], options.start_addr);
            break;

        default:
            break;
    }

    return stat;
}

int CPCOutput(const char *filename, const char *filename_bank,
              MemoryBank **bank, int count, char *error, size_t error_size)
{
    FILE *fp = fopen(filename, "wb");
    int f;
    int offset;

    if (!fp)
    {
        snprintf(error, error_size, "Failed to create %s", filename);
        return FALSE;
    }

    /* Write signature
    */
    WriteString(fp, "C64 tape image file", 32, 0, CP_ASCII);

    /* Write directory header
    */
    WriteWord(fp, 0x200);
    WriteWord(fp, count);
    WriteWord(fp, count);
    WriteString(fp, filename, 24, ' ', CP_ASCII);

    /* Offset to tape data
    */
    offset = 64 + 32 * count;

    /* Write directory entries
    */
    for(f = 0; f < count; f++)
    {
        int min, max, len;

        min = bank[f]->min_address_used;
        max = bank[f]->max_address_used;

        /* If this is the first bank, we're going to prepend some BASIC
        */
        if (f == 0)
        {
            if (min < 0x810)
            {
                snprintf(error, error_size, "First bank starts below a safe "
                                            "area to add BASIC loader");

                return FALSE;
            }

            min = 0x801;        /* Start of BASIC */
        }

        len = max - min + 1;

        WriteByte(fp, 1);
        WriteByte(fp, 0x82);
        WriteWord(fp, min);
        WriteWord(fp, max + 1);
        WriteLong(fp, offset);

        if (count == 1)
        {
            WriteString(fp, filename, 16, ' ', CP_CBM);
        }
        else
        {
            char fn[16];

            snprintf(fn, sizeof fn, filename_bank, bank[f]->number);
            WriteString(fp, fn, 16, ' ', CP_CBM);
        }

        /* +2 is to include the 2-byte PRG header
        offset += len + 2;
        */
        offset += len;
    }

    /* Write actual contents
    */
    for(f = 0; f < count; f++)
    {
        Byte *mem;
        int min, max, len;

        mem = bank[f]->memory;

        min = bank[f]->min_address_used;
        max = bank[f]->max_address_used;

        /* If this is the first bank, we're going to prepend some BASIC.
           Note that output drivers are allowed to manipulate memory directly.
        */
        if (f == 0)
        {
            char sys[16];
            int a = 0x803;
            int next;

            snprintf(sys, sizeof sys, "%u", min);

            a = PokeW(mem, a, 10);
            a = PokeB(mem, a, 0x9e);
            a = PokeS(mem, a, sys);
            a = PokeB(mem, a, 0x00);

            next = a;

            a = PokeW(mem, a, 0x00);

            PokeW(mem, 0x801, next);

            min = 0x801;
        }

        len = max - min + 1;

        fwrite(mem + min, len, 1, fp);
    }

    fclose(fp);

    return TRUE;
}


/*
vim: ai sw=4 ts=8 expandtab
*/